asme b31.8 interpretations volume 16 - تجهیزکالا b31.8 interpretations... · 2018. 12....

ASME B31.8 INTERPRETATIONS VOLUME 16

ASME B31.8 INTERPRETATIONSVOLUME 16

Replies to Technical InquiriesMarch 2010 Through March 2012

Interpretations 16-1 Through 16-17

It has been agreed to publish interpretations issued by the B31 Committee concerningASME B31.8 as part of the update service to the Code. The interpretations have been asssignednumbers in chronological order. Each interpretation applies either to the latest Edition or Addendaat the time of issuance of the interpretation or the Edition or Addenda stated in the reply.Subsequent revisions to the Code may have superseded the reply.

These replies are taken verbatim from the original letters, except for a few typographical andeditorial corrections made for improved clarity.

ASME procedures provide for reconsideration of these interpretations when or if additionalinformation that the inquirer believes might affect the interpretation is available. Further, personsaggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee.As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,”“rate,” or “endorse” any item, construction, proprietary device, or activity.

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B31.8Subject Interpretation File No.

Appendix F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-11 11-376Para. 802.12(f), Injection and Production Flow Lines . . . . . . . . . . . . . . . . . . . . . . . . . 16-13 07-1469,

07-1470Para. 831.2.2, ASTM A307 Grade B Bolting for B16.5 Flanges in Classes 150

and 300 Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-4 10-718Para 831.2.2, Follow-Up Inquiry on ASTM A307 Grade B Bolting for

B16.5 Flanges in Classes 150 and 300 Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-10 11-371Para. 831.4.1(c) and Appendix F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-8 09-1699Para. 841.31, General Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-3 07-1472Para. 842.2, Design of Plastic Piping, General Provisions . . . . . . . . . . . . . . . . . . . . . 16-9 10-1001Para. 845.2.2, MAOP and Para. 845.4.1, Capacity of Pressure-Relieving

and Pressure-Limiting Stations and Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-14 10-1195Para. 845.4.1, Transient Overpressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-16 11-1574Para. 845.411, Hoop Stress Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-2 10-162Para. A842.2.2, Design Against Yielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-12 11-377Para. A842.2.2, Design Against Yielding and Para. A842.2.3, Alternate Design

for Strain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-15 11-1573Paras. A842.2.2(a), A842.2.2(b), and A842.2.2(c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-1 10-23Para. A842.2.2(a), Hoop Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-6 10-1056Para. A842.2.2(a), Hoop Stress and Para. A847.2, Test Pressure . . . . . . . . . . . . . . . . 16-5 10-1057Para. A842.2.2(a), Hoop Stress and Para. A847.2, Test Pressure . . . . . . . . . . . . . . . . 16-7 10-1644Para. A847.2, Test Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-17 12-121

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Interpretation: 16-1

Subject: ASME B31.8-2007, Paras. A842.2.2(a), A842.2.2(b), and A842.2.2(c)

Date Issued: March 10, 2010

File: 10-23

Question (1): The equation for hoop stress in para. A842.2.2(a) has a temperature deratingfactor in the formula, whereas the equations for longitudinal stress and combined stress inparas. A842.2.2(b) and A842.2.2(c) do not use a temperature derating factor. Is this correct?

Reply (1): Yes.

Question (2): Does ASME B31.8 use temperature derated values of Specified Minimum YieldStrength?

Reply (2): No.


Subject: ASME B31.8-2007, Para. 845.411, Hoop Stress Calculations


File: 10-162

Question (1): Is it allowed to use the Lame formula to determine hoop stress when determiningincidental pressure for an onshore pipeline in accordance with para. 845.411?

Reply (1): No.

Question (2): Is it required to multiply the hoop stress by the Location Class Basic DesignFactor, F, for the capacity check per para. 845.411?

Reply (2): No.


Subject: ASME B31.8-2003, Para. 841.31, General Provision

Date Issued: June 30, 2010

File: 07-1472

Question (1): With respect to para. 841.31, is a flange-end valve considered to be a nonweldedtie-in connection?

Reply (1): Yes, provided the valve serves as a tie-in point after construction and testing of thepipeline or piping.

Question (2): Is it mandatory for a pretested flange-end valve to be part of the piping systemduring hydrotesting?

Reply (2): No. Per para. 841.31, nonwelded tie-in connections not pressure tested after construc-tion shall be leak tested.

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Subject: ASME B31.8-2010; Para. 831.2.2, ASTM A307 Grade B Bolting for B16.5 Flanges inClasses 150 and 300 Service

Date Issued: July 7, 2010

File: 10-718

Question: Does ASME B31.8 allow the use of ASTM A307 Grade A bolts in addition to Grade Bbolts in para. 831.2.2(b)?

Reply: No.


Subject: ASME B31.8-2010, Para. A842.2.2(a), Hoop Stress and Para. A847.2, Test Pressure


File: 10-1057

Question (1): In para. A842.2.2(a), eq. (2) is for thin-walled pipe, and eq. (3) is for thick-walledpipe. However, if we go by what is given in these two Code equations, the pipe thickness forthick-walled pipes will be less than the pipe thickness for thin-walled pipes. Therefore, is therea typographical or drafting error in eqs. (3) and (5) in this section?

Reply (1): The equations are all correct, but it is not clearly identified that eqs. (2) and (4) arefor U.S. Customary Units and that eqs. (3) and (5) are for SI Units. Furthermore, there is apublishing error in the Note following these equations. The Note should read: “It is recommendedthat eq. (2) or (3) be used for D/t greater than or equal to 30 and that eq. (4) or (5) be used forD/t less than 30.” Errata has been issued to correct these publishing errors.

Question (2): We have a pipeline where the corrosion allowance is 6 mm and 12.5% fabricationallowance. Is the hoop stress calculation under ASME B31.8, Chapter VIII (para. A842.2.2) to bebased only on nominal wall thickness?

Reply (2): Yes.

Question (3): If no, then what are the maximum limits for corrosion and fabrication allowancesbeyond which we need to factor them while calculating the Hoop Stress?

Reply (3): The hoop stress calculations under ASME B31.8, Chapter VIII are to be based onlyon nominal wall thickness.

Question (4): When reading paras. A842.2.2(a) and A847.2, our interpretation for F1, hoop stressdesign factor for offshore pipelines, for a pressure test is that it should be equal to 1. Therefore,is it correct to take the F1 design factor for offshore pipelines for a pressure test to be equal to 1?

Reply (4): No. As stated in Table A842.2.2-1, the hoop stress design factor, F1, for offshorepipelines shall be 0.72. There is no hoop stress design factor, F1, for pressure tests.

Question (5): If no, then what is the correct design factor for the above case?

Reply (5): See reply to Question (4).

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Subject: ASME B31.8-2010, Para. A842.2.2(a), Hoop Stress

Date Issued: October 20, 2010

File: 10-1056

Question: Can the hoop stress formula in para. A842.2.2(a), eq. (4), be revised as noted below?For an isotropic elastic pipe, this technical inquiry proposes the following formulation for hoopstress calculation.

Sh p (Pi − Pe)� − Pi (1)

where

� p �2�� tD� − � t

D�2

�−1

p 2�Ao

As� (2)

Ao p external cross sectional area of pipeAs p pipe material cross sectional area (cross sectional area of pipe steel)

The proposed formulation, eq. (1), is based on Lame’s solution for hoop stress at the insidediameter of a cylinder subject to a differential pressure, i.e., internal and external pressure.Equation (1) predicts the hoop stress exactly when results are compared to finite element solutionusing eight-node solid continuum element.

The proposed formulation of eq. (1) is a replicate of the second equation of para. A842.2.2(a)but in a more concise and a practical format. The proposed hoop stress formulation of eq. (1) isin terms of Ao and As (i.e., pipe outer and material cross-sectional areas), which gives a directimplication of material usage in resisting the tensile hoop stress. The proposed hoop stressformulation is also shown in terms of wall thickness-to-diameter ratio (t/D), to assist designersin performing normalized parametric studies.

The proposed formulation of eq. (2) is more appropriate for deepwater application, wherehydrostatic collapse pressure often results in pipe diameter-to-wall thickness ratios of less than20, where the existing equation in ASME B31.8 may grossly overestimate the hoop stress.

Reply: Thank you for your considered discussion on the hoop stress equation formulation.However, use of the proposed Lame equation to compute the hoop stress at the pipeline internaldiameter for offshore pipelines does not have any significant advantage over the current equation,and is more difficult to use for development of pipeline wall thickness design. We do not agreewith your assertion that the formula in para. A842.2.2(a), eq. (4) will grossly overestimate thehoop stress. We consider that the existing eq. (4) in para. A842.2.2(a) is appropriate for the D/tranges covered in ASME B31.8.

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Subject: ASME B31.8-2010, Para. A842.2.2(a), Hoop Stress and Para. A847.2, Test Pressure

Date Issued: November 9, 2010

File: 10-1644

Question: Previously, I had sent an Inquiry to ASME asking if it was correct to take the F1design factor for offshore pipelines for a pressure test to be equal to 1 when considering thewording stated in paras. A842.2.2(a) and A847.2. The reply to this Inquiry (Interpretation 16-5,File 10-1057) stated that there is no hoop stress design factor, F1, for pressure tests. However, Ihave an additional question related to this response. Is the following the correct formula forcomputing the hoop stress for a pressure test?

S ≤ ST

Reply: No. There is no maximum hoop stress limit identified in the Code for a hydrotest. TheCautionary Note in para. A847.2 was written to caution the Code user that conditions may existthat could yield the pipe.


Subject: ASME B31.8-2010, Para. 831.4.1(c) and Appendix F


File: 09-1699

Question: In a fabricated branch connection, where the opening made in the header wall issmaller than the inside diameter of the branch pipe, may the full thickness of the header wallbetween the undersized branch hole and the inside of the branch pipe be considered to bereinforcement for purposes of area replacement calculation?

Reply: Yes.

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Subject: ASME B31.8-2010, Para. 842.2 Design of Plastic Piping, General Provisions


File: 10-1001

Question (1): Reinforced thermoplastic pipe (RTP) as described in, for example, ISO TS 18226,Plastics pipes and fittings — Reinforced thermoplastics pipe systems for the supply of gaseousfuels for pressures up to 4 MPa (40 bar), or API RP 15S, Qualification of Spoolable ReinforcedPlastic Line Pipe, is not specifically identified as acceptable in para. 842.2. Is RTP allowed to beused for gas pipeline service?

Reply (1): No. However, certain products may be qualified for use by methods described insection 811.

Question (2): Is reinforced thermoplastic pipe (RTP) subject to the same pressure design limita-tions as thermoplastic pipe per para. 842.2.2?

Reply (2): No. See response to Question (1). The ASME B31.8 Code Committee is consideringmodifications to the current code specifically to include certain types of reinforced thermoplasticpipe that may be described in API RP 15S, ISO TS 18226, and other reinforced thermoplastic pipestandards.


Subject: ASME B31.8-2010, Para 831.2.2, Follow-Up Inquiry on ASTM A307 Grade B Bolting forB16.5 Flanges in Classes 150 and 300 Service


File: 11-371

Question (1): Is there a conflict between ASME B31.8, para. 831.2.2 referencing ASME B16.5and ASTM A307, Grade B bolting?

Reply (1): No. ASME B16.5 references ASTM A307 Grade B bolts in Table 1B under the categoryof Low Strength Bolting. In ASME B16.5, the Grade B bolts are limited to use with Classes 150and 300 flanged joints, used with nonmetallic gasket materials at temperatures between −29°Cto 200°C (−20°F to 400°F). These same conditions are required in ASME B31.8, para. 831.2.2. [Thetemperature range in the ASME B31.8-2010 actually reads −29°C to 232°C (−20°F to 450°F). Thereis an errata scheduled for publication to correct the high temperature discrepancy.] TheASTMA307statement that the Grade B bolts are intended for use with cast iron flanges does not precludetheir use in steel flanges under the conditions stated above.

Question (2): Since ASME B31.8 is referencing ASME B16.5, which is for steel flanges, shouldn’tit also reference ASTM A307, Grade A bolts since these are used for general purpose (steel)?

Reply (2): No. ASTM A307, Grade A bolts are not referenced in ASME B16.5. The Grade Abolts allow sulfur levels up to 0.15% for ease of machining, and therefore may possess low fracturetoughness properties unsuitable for natural gas service.

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Subject: ASME B31.8-2010, Appendix F


File: 11-376

Question (1): In the examples in Appendix F illustrating the application of the rules for reinforce-ment of welded branch connections for an onshore pipeline system, is the Design Factor, F, takenfrom Table 841.1.6-1?

Reply (1): No. A welded branch connection on an onshore pipeline system is a FabricatedAssembly, as defined in para. 841.1.9(a). Therefore, the Design Factor, F, is taken fromTable 841.1.6-2.

Question (2): In the examples in Appendix F illustrating the application of the rules for reinforce-ment of welded branch connections, would the Design Factor, F, be taken from the Hoop Stresscolumn in Table A842.2.2-1 for an offshore pipeline system?

Reply (2): Yes.


Subject: ASME B31.8-2010, Para. A842.2.2, Design Against Yielding


File: 11-377

Question (1): My understanding of the test pressure criterion is the following:

Sh p (Pi − Pe)D2t

< SMYS

Is this correct?

Reply (1): No. The formula that you have noted is used to compute hoop stress. It is not a testpressure criterion. Furthermore, Sh as defined in eqs. (1) and (2) in para. A842.2.2 includes aDesign Factor, F, and a Temperature Derating Factor, T.

Question (2): Since the nominal wall thickness is used in eq. (2) in para. A842.2.2 to computehoop stress, does this mean that during a hydrotest, ASME B31.8 allows hoop stress to be 12.5%higher than SMYS when assuming a pipe manufacturing mill tolerance of −12.5%?

Reply (2): No. When the Design Factor is included in the hoop stress formula, the hoop stressduring a hydrotest will not be 12.5% higher than SMYS.

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Subject: ASME B31.8-2007, Para. 802.12(f), Injection and Production Flow Lines


File: 07-1469 and 07-1470

Question (1): In accordance with ASME B31.8-2007, does the Code exclude flow lines betweengas injection wells and gas injection facilities?

Reply (1): Yes.

Question (2): In accordance with ASME B31.8-2007, does the Code exclude flow lines betweengas production wells and gas separation facilities?

Reply (2): Yes.


Subject: ASME B31.8-2007, Para. 845.2.2, MAOP and Para. 845.4.1, Capacity of Pressure-Relievingand Pressure-Limiting Stations and Devices

Date Issued: September 16, 2011

File: 10-1195

Question (1): Is the Maximum Allowable Working Pressure (MAWP) in para. 2.1 ofASME B16.5-2009 is the same as the Maximum Allowable Operating Pressure (MAOP) inpara. 845.2.2 of ASME B31.8-2007?

Reply (1): No, they are not the same. The MAWP from ASME B16.5 should be used as one ofthe criteria in determining the MAOP of the pipeline system.

Question (2): Do the requirements for pressure-relieving and pressure-limiting stations anddevices per para. 845.4.1(a)(2)(a) allow the pressure set point to be MAWP plus 10%?

Reply (2): No. Paragraph 845.4.1(a)(2)(a) requires that the relieving device prevent the pressurefrom exceeding the MAOP plus 10%. Note that para. 845.4.1(a)(2)(b) has an additional limitationon the device set point when 75% of SMYS is less than the hoop stress at 110% of the MAOP.

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Subject: ASME B31.8-2010, Para. A842.2.2, Design Against Yielding and Para. A842.2.3, AlternateDesign for Strain

Date Issued: December 9, 2011

File: 11-1573

Question (1): Are the provisions on pipe longitudinal and combined stresses defined in para.A842.2.2 applicable to deepwater pipelines in service that are not pressurized temporarily? Inparticular, are these stress limits applicable to pipeline local buckling check per API RP-1111,para. 4.3.2.2, which allows pipe bending well into the plastic region for pipe with low diameterto wall thickness ratio? For the purpose of this question, it is assumed that this is an expectedcondition that occurs periodically during the intervals of pipeline system operating cycles, andall fatigue issues (including potential low cycle fatigue issues) have been checked.

Reply (1): If the pipeline design uses stress-based criteria, the Code requirements inpara. A842.2.2 shall be met. If the pipeline design uses strain-based criteria, the Code requirementsin para. A842.2.3 and A842.2.4 shall be met.

Question (2): Is para. A842.2.3 applicable to subsea pipelines that are not pressurized duringan emergency, noncyclic event?

Reply (2): Yes.


Subject: ASME B31.8-2010, Para. 845.4.1, Transient Overpressure

Date Issued: January 13, 2012

File: 11-1574

Question (1): ASME B31.8-2010, para. 845.4.1 explains that the pressure-relieving and pressure-limiting stations should be set to limit pressures from exceeding the lesser of MAOP + 10%, orhoop stress p 75% SMYS, for high-pressure distribution systems operating at hoop stress levelsat or below 72% SMYS. Is “hoop stress p 75% SMYS” referring to hoop stress of any componentof the pipeline system, or hoop stress of the pressure limiting device?

Reply (1): The requirements of para. 845.4.1(a)(2) are applicable to pipe or pipeline components.

Question (2): Can gas pipelines be designed to have transient overpressures up to 10% aboveMAOP, similar to ASME B31.4?

Reply (2): No.

Question (3): If gas pipelines are allowed transient overpressures up to 10% above MAOP, doesthe 0.72 hoop stress factor for operation conditions account for the possibility of 10% transientoverpresure?

Reply (3): Since the Reply to Question (2) is “No,” Question (3) is not applicable, because gaspipelines shall not be designed to have transient overpressures up to 10% above MAOP.

Question (4): Are gas pipelines allowed to operate at transient overpressures up to 10% aboveMAOP when MAOP is equal to the Design Pressure?

Reply (4): No.

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Subject: ASME B31.8-2010, Para. A847.2, Test Pressure


File: 12-121

Question: When the ASME B31.8 Code refers to Maximum Allowable Operating Pressure(MAOP) in para. A847.2, in order to set the hydrostatic test pressure for an offshore pipelinesegment, is it referring to the MAOP at one set elevation at the highest point of the pipelinesegment (e.g., at the compressor discharge)?

Reply: Yes.

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INTENTIONALLY LEFT BLANK


Replies to Technical InquiriesJanuary 2007 Through September 2009


It has been agreed to publish interpretations issued by the B31 Committee concerningASME B31.8 as part of the update service to the Code. The interpretations have been asssignednumbers in chronological order. Each interpretation applies either to the latest Edition or Addendaat the time of issuance of the interpretation or the Edition or Addenda stated in the reply.Subsequent revisions to the Code may have superseded the reply.



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Allowable Hoop Stress for Offshore Hydrotest, Para. A847.2 . . . . . . . . . . . . . . . . . . 15-11 09-1503Alternate Acceptance Standard for Girth Welds in Appendix A of

API 1104 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-10 09-1073Para. 831.41(h), Seal Welding Vent Holes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-4 06-259Para. 834.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-8 07-1468Para. 841.11(c), Fracture Control and Arrest for Steel Pipe . . . . . . . . . . . . . . . . . . . . 15-5 03-105Para. 841.32 and Table 841.322(f), Testing Coefficients . . . . . . . . . . . . . . . . . . . . . . . . 15-2 04-94Para. 844.32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-6 04-1083Paras. A801, A802, and A803, Minimum Temperature Application. . . . . . . . . . . . . 15-1 04-1649Table 841.115A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-3 05-215Table 841.322(f), Maximum Test Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-7 06-1146Table A842.11, Note (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-9 09-1072

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Subject: ASME B31.8-2003, Sections A801, A802, and A803, Minimum Temperature Application


File: 04-1649

Question (1): We would like to know if "General Provisions and Definitions" (in particular,para. 802.12(b)) is completely replaced by Chapter VIII, sections A801, A802, and A803.

Reply (1): No. As stated in para. A802.2, the provisions of paras. A801, A802, and A803 onlysupplement the provisions of paras. 801, 802, and 803. They do not replace them.

Question (2): If so, which is the minimum applicable temperature for Offshore Gas TransmissionInstallation?

Reply (2): As stated in para. 802.12(b), the B31.8 Code is only applicable to pipelines havinga metal temperature down to and including −20°F.


Subject: ASME B31.8, Para. 841.32 and Table 841.322(f), Testing Coefficients


File: 04-94

Question: Why is the coefficient for the Location Class 1, Division 1 higher than 1.1?

Reply: The coefficient reflects the Committee’s opinion about the minimum test level necessaryto establish the pipeline’s integrity for pipelines operating at a hoop stress above 72% of theSMYS.


Subject: ASME B31.8, Table 841.115A

Date Issued: May 21, 2007

File: 05-215

Question: Would helical (spiral) welded pipe have the same joint efficiency factor (E p 1.0) asSAW pipe manufactured under API 5L?

Reply: Yes.

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Subject: ASME B31.8, Para. 831.41(h), Seal Welding Vent Holes


File: 06-259

Question (1): Is seal welding acceptable for plugging vent holes?

Reply (1): No. The Code recommends against the use of any material or techniques that wouldcontain pressure for plugging vent holes in rings or saddles used for reinforcement of branchconnections [see para. 831.41(h)].

Question (2): Can seal welding of vent holes on wear pads for pipe supports be used to preventcrevice corrosion?

Reply (2): The Code does not address wear pads.


Subject: ASME B31.8, Para. 841.11(c), Fracture Control and Arrest for Steel Pipe


File: 03-105

Question (1): Is material testing required to confirm that fracture toughness criteria specifiedin accordance with para. 841.11(c) has been achieved?

Reply (1): Yes. Testing in accordance with paras. 841.11(c)(1) and (c)(2) is required.

Question (2): Is material testing required to confirm that the all-heat average Charpy energyvalue meets or exceeds the required energy value as determined in accordance withpara. 841.11(c)(2)?

Reply (2): Yes.


Subject: ASME B31.8-2003, Para. 844.32


File: 04-1083

Question (1): Is gas process piping (such as pipelines, headers, manifolds, etc), whether installedabove or below ground, defined as a pipe-type or bottle-type holder?

Reply: (1) No.

Question (2): If the answer to Question (1) is negative, then does the Code provide criteria forestablishing the distance from gas process piping to property and/or fence lines?

Reply (2): No.

Question (3): Do the requirements of para. 844.32(b) prohibit the installation of pipe-type andbottle-type holders less than 100 ft from a fenced site boundary when the maximum operatingpressure is greater than or equal to 1,000 psig?

Reply (3): Yes.

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Subject: ASME B31.8, Table 841.322(f), Maximum Test Pressure


File: 06-1146

Question (1): Is there a maximum test pressure prescribed for location class-2 when the testmedium is water?

Reply (1): No.

Question (2): Is there a maximum test pressure prescribed for location class-3 and 4 when thetest medium is water?

Reply (2): No.


Subject: ASME B31.8, Para. 834.5


File: 07-1468

Question (1): For piping that is operating at 50% or more of SMYS, and a welded pipe supportconnection is desired, is it necessary to provide a full encirclement sleeve, continuously weldedto the pipe, for attachment of the welded pipe support?

Reply (1): Yes.

Question (2): For piping that is operating at 50% or more of SMYS, is it necessary to providea full encirclement sleeve (welded or not welded) to the pipe when a nonwelded support connec-tion is desired (such as a clamp)?

Reply (2): No.


Subject: ASME B31.8-2007 Edition, Table A842.11, Note (1)


File: 09-1072

Question: Note (1) in Table A842.22 says combined stress for platform piping and risers shallbe based upon specified minimum wall thickness, including manufacturing, corrosion, and erosionallowances. Is combined stress for pipeline to be based on nominal wall thickness?

Reply: Yes.

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Subject: ASME B31.8-2007, Alternate Acceptance Standard for Girth Welds in Appendix A ofAPI 1104


File: 09-1073

Question: Can the alternative acceptance standard for girth welds described in Appendix Aof API 1104 be applied for onshore pipeline construction according to ASME B31.8?

Reply: Yes. Meeting the standards of acceptability of API 1104 implies the use of the documentin its entirety, including the appendices.


Subject: ASME B31.8-2007 Edition, Allowable Hoop Stress for Offshore Hydrotest, Para. A847.2


File: 09-1503

Question: In ASME B31.8-2007, para. A847.2, it is addressed in the CAUTION section that“When an external pressure, Pe, greater than zero is used in the hoop stress formula in para.A842.221, there is a possible combination of conditions where the yield strength of the pipe couldbe exceeded during the hydrostatic test. The hoop stress shall be checked to see that it is withinallowable limits considering both the internal and external pressures when determining themaximum hydrostatic test pressure.” However, it is not specified in the code what should be theallowable limit for the hoop stress during hydrotest. Is there an allowable limit for the hoopstress during hydrotest of an offshore pipeline?

Reply: No. The Code does not limit the hoop stress during hydrotest of an offshore pipelineto a certain percentage of SMYS. The purpose of the cautionary note is only to alert the user thatunder certain conditions, the hoop stress during hydrotest could be higher than anticipated.

I-6


Replies to Technical InquiriesJanuary 2004 Through December 2006


It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8as part of the update service to the Code. The interpretations have been asssigned numbers inchronological order. Each interpretation applies either to the latest Edition or Addenda at thetime of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequentrevisions to the Code may have superseded the reply.



I-1



Code Conformance of Flanges Listed to ASME B16.47 . . . . . . . . . . . . . . . . . . . . . . . 14-3 02-2884Establishment of tmin for B31.8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-8 03-1739New Road in Parallel Encroachment With an Existing Pipeline. . . . . . . . . . . . . . . . 14-4 02-2547Para. 802.11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-5 03-158Para. 833.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-7 02-3377Para. 846.11(c), Sectionalizing Valve Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-2 02-2542Para. 851.51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-9 04-246Para. A842.223, Combined Stress Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-1 B31-99-002Paras. A834 and A842.27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-6 03-1792Table 854.1(c), Change in Number of Buildings With Respect to Location

Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-10 04-93

I-2



Subject: ASME B31.8-1995 Edition, Para. A842.223, Combined Stress Criteria

Date Issued: August 3, 1999

File: B31-99-002

Question (1): Are either the Von Mises or Tresca equations acceptable under para. A842.223for considering combined stress?

Reply (1): Yes.

Question (2): In para. A842.223, does “limiting longitudinal stress” mean limiting combinedstress?

Reply (2): Yes.


Subject: ASME B31.8, Para. 846.11(c), Sectionalizing Valve Spacing


File: 02-2542

Question: Except for the slight adjustments permitted in para. 846.11(c), are there any provisionsin the B31.8 Code that will allow a spacing of valves in a Class 1 Location to exceed 20 miles?

Reply: No.


Subject: ASME B31.8-1999 Edition, Code Conformance of Flanges Listed to ASME B16.47


File: 02-2884

Question: Does the ASME B31.8 Code permit the use of flanges manufactured in accordancewith ASME B16.47 (Series A or B)?

Reply: Yes; refer to section 811 of ASME B31.8 for additional information regarding qualificationof materials and equipment for use in this Code.

I-3



Subject: ASME B31.8-1999 Edition, New Road in Parallel Encroachment With an Existing Pipeline

Date Issued: February 12, 2004

File: 02-2547

Question (1): An existing pipeline was originally located in a Class 1, Division 2 location usinga Design Factor of 0.72. There were no roads when the pipeline was built. A new road has beenbuilt within the same right-of-way. Does section 854, Criteria for Class Location, apply?

Reply (1): No.

Question (2): An existing pipeline is located in a Class 1, Division 2 Location and a DesignFactor of 0.72 was used. If there is an existing parallel encroachment with a private road orunimproved public road, and a new railroad is built within the pipeline right-of-way, does section854 apply to determine the MAOP?

Reply (2): No.

Question (3): Does the Code address the addition of fences or surfacing of roads after thepipeline is constructed?

Reply (3): No.

Question (4): In case of a pipeline located in a Class 1, Division 2 area that crosses withoutcasing a public road, improved or unimproved, and also crosses its right-of-way, is the portionof the pipeline that runs in the land between the right-of-way limit and the road considered (forthe purpose of Design Factor and depth of cover):

(a) a part of the crossing?(b) as if it were a parallel encroachment?(c) as a common portion of pipe in Class 1, Division 1, with a Design Factor of 0.72?

Reply (4): The portion of the pipeline between the right-of-way and the road is considered apart of the crossing.

Question (5): With regard to Table 841.114B, under “Crossing of roads . . .”, item (c), does thisapply to roads or highways or public streets with both hard surface and railroads (rails installedon hard surface street, with lanes for cars and lanes for trains), or does this apply to roads orhighways or public streets with a hard surface and railroads?

Reply (5): It is applicable to roads or highways or public streets with hard surface and alsoapplicable to railroads, wherever the railroads are located.

Question (6): Does para. 840.22(d) include areas where all of the following conditions arepresent:

(a) multistory buildings are prevalent(b) traffic is heavy or dense(c) there may be numerous utilities underground

Reply (6): Yes. Note para. 840.22(d) also defines “multistory” as four or more floors. In Class 4Locations, all of the above must exist.

I-4



Subject: ASME B31.8-1999 Edition, Para. 802.11


File: 03-158

Question: Do the corresponding chapters (Materials, Welding, Design, and Testing) ofASME B31.8 apply to underground ethylene pipelines operating in gas phase below the criticalpoint (50.3 bar), considering

(a) it is not a fuel line(b) it was located onshore(c) it is 140 km long and links two plants together(d) it will be operating at below 50–55 bars(e) it will be transporting ethylene in the gaseous phase(f) the line was originally designed for oxygen service to ASME B31.8–1975 Edition.

Reply: The answer based on the above is yes.


Subject: ASME B31.8-1999 Edition, Paras. A834 and A842.27


File: 03-1792

Question (1): A portion of the topsides between the riser hangar flange and the launcher/receiver is specified as per B31.8 in lieu of B31.3 in order to maintain the constant inside diameterof the pipe for pigging. Does the pipe support attachment require a full encircling member inaccordance with para. A834 since the portion of piping referenced above is not construed as ariser or a pipeline?

Reply: (1) Yes. We agree that the portion of piping you are considering is not a riser or apipeline, but it is platform piping. Since para. A834 also covers platform piping, it does indeedrequire a full encircling member in order to be in accordance with ASME B31.8.

Question (2): If the support is welded to a 120 deg pad by avoiding the direct welding of thesupport to the piping and the computed local stress due to the support reaction is within theCode allowable, does it suffice as per para. A842.27?

Reply (2): No. In order to be in accordance with ASME B31.8, you need to use a full encirclingmember.

I-5





File: 02-3377

Question (1): The last statement of para. 833.4 in the 1995 revision of the Code appears as,“The sum of 833.4(b) and (c) shall not exceed 0.75S”; however, para. 833.4(b) has the followingstatement added in parentheses: “(see para. 841.11, SFT)”. Does the following equation interpretcorrectly these two revised statements?

0.75 � F � T � SLP + SLB < S

Reply (1): No.

Question (2): Or should it look now as: SLP + SLB < S?

Reply (2): No.


Subject: ASME B31.8, Establishment of tmin for B31.8


File: 03-1739

Question: Can ASME B31G be used to determine a minimum wall thickness for new pipe?

Reply: No.




File: 04-246

Question: Does field bending a joint of pretested pipe negate the test, thus requiring a post-bend test?

Reply: ASME B31.8 is silent on this issue.


Subject: ASME B31.8-2003 Edition, Table 854.1(c), Change in Number of Buildings With Respectto Location Class


File: 04-93

Question: Can the “current” column in Table 854.1(c) be used for the purpose of patrols andleakage surveys [paras. 854.1(d) and 851.2]?

Reply: Yes.

I-6


Replies to Technical InquiriesJuly 2001 Through December 2003Interpretations 13-1 Through 13-8

It has been agreed to publish intepretations issued by the B31 Committee concerning B31.8 aspart of the update service to the Code. The interpretations have been asssigned numbers inchronological order. Each interpretation applies either to the latest Edition or Addenda at thetime of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequentrevisions to the Code may have superseded the reply.



I-1

B31.8

Subject Interpretation File No.

Paras. 823.21, 824.1, 825.1, and 825.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-7 03-154Para. 831.22(d), Bolting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-5 B31-01-004Para. 831.41(d) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-2 B31-99-032Para. 833 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-1 B31-00-002Paras. 841.321, 841.33, and 852.51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-6 02-3938Para. 854.4(b)(2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-4 02-3705Appendix F, Fig. F5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-8 03-155Code Conformance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-3 B31-01-005

I-2

13-1, 13-2 ASME B31.8-2003


Subject: ASME B31.8, Para. 833


File: B31-00-002

Question (1): Does para. 833.4(b) require that the longitudinal stress due to internal pressurebe calculated using the pressure design equation in para. 841.11?

Reply (1): No.

Question (2): Does para. 833.2 require that stresses due to weight of the pipe be combined withstresses due to thermal expansion?

Reply (2): No.

Question (3): Does para. 833.4 apply to a fully restrained section of pipeline?

Reply (3): No.

Question (4): Does para. 833.4 limit the thermal expansion stress range to 0.72 SMYS, the sumof longitudinal stresses due to pressure and weight to 0.75 SMYS, and the sum of the thermalexpansion stress range and the longitudinal stresses due to pressure and weight to 1.0 SMYS?

Reply (4): Yes.

Question (5): Do we need to consider the longitudinal joint factor E in the calculation ofallowable hoop stress for offshore pipelines as specified in para. 841.11 for onshore pipelines?

Reply (5): No.

Question (6): Can a hoop stress design factor of 0.80 be used for an offshore pipeline design?

Reply (6): No.


Subject: ASME B31.8, Para. 831.41(d)

February 14, 2002

File: B31-99-032

Question: Where the diameter of the finished opening for a branch connection is smaller thanthe inside diameter of the branch pipe, is it permissible to include as available reinforcementexcess thickness in the header wall located between the finished opening and the branch wall.

Reply: Yes.

I-3

ASME B31.8-2003 13-3, 13-4, 13-5, 13-6


Subject: ASME B31.8 Code Conformance of Pikotek Flanges


File: B31-01-005

Question: In order to comply with the Code requirements of ASME B31.8, is it permissible touse Pikotek gaskets as unlisted components in standard B16.5 flanges and operate at higherworking pressures and temperatures than those listed in ASME B16.5-1996 (Tables 2 listed underPressure–Temperature Ratings) provided the calculated flange (and bolt) stresses remain belowthe allowable stresses outlined in the applicable ASME Boiler and Pressure Vessel Code (asspecifically detailed in memorandum titled “Code Conformance of Pikotek Flanges” dated April7, 1997)?

Reply: No.


Subject: ASME B31.8-1999, Para. 854.4(b)(2)


File: 02-3705

Question: Is it mandatory, per para. 854.4(b)(2) that additional sectionalizing block valves beinstalled to conform to the spacing requirements in para. 846.11, when one mile or more oftransmission line is replaced to maintain the established MAOP in conjunction with a change inlocation class?

Answer: No.


Subject: ASME B31.8, Para. 831.22(d), Bolting


Item: B31-01-004 (formerly B31-00-003)

Question (1): Do ASTM A 563 nuts meet the requirements set forth in para. 831.22(d) for usewith ASTM A 307 bolts?

Reply (1): No. As written, only ASTM A 194 or A 307 may be used. However, per para. 811.22,other materials may be qualified for use as described in para. 811.221 or para. 811.222.

Question (2): If ASTM A 563 nuts meet the requirements set forth in para. 831.22(d), are GradeA, Heavy Hex nuts required to match ASTM A 307 Grade B bolts?

Reply (2): See Reply 1.


Subject: Appendix F, Fig. F5, Definition of dimension L


File: 03-155

Question: If the L dimension for a welded-on fitting (integrally reinforced) lies entirely withinthe fitting, then for the purposes of extra area replacement per para. 831.41(e), is L then equal to21⁄2H, where H is the nominal wall thickness of the header?

Reply: Yes, provided 21⁄2H is smaller than 21⁄2B + M.

I-4

13-7, 13-8 ASME B31.8-2003


Subject: Paras. 823.21, 824.1, 825.1, and 825.2


File: 03-154

Question (1): Is it mandatory that welds in all carbon steels be stress relieved when thewall thickness exceeds 11⁄4 in. even if hardness requirements have been achieved without stressrelieving?

Reply (1): Yes, ASME B31.8 para. 825.2 requires carbon steel welds shall be stress relieved whenthe nominal wall thickness exceeds 11⁄4 in.

Question (2): Is preheating mandatory for carbon steels having a carbon content less than 0.32%or a carbon equivalent (C + 1⁄4 Mn) less than 0.65%?

Reply (2): No, unless the weld procedure requires such treatment to produce satisfactory welds.

Question (3): Is stress relieving mandatory for carbon steels having a carbon content less than0.32% or a carbon equivalent (C + 1⁄4 Mn) less than 0.65%?

Reply (3): No, provided all of the other requirements are met.

Question (4): If a weld procedure for sour gas service is qualified under ASME para. IX andthe procedure meets the hardness requirements as specified in NACE MR0175 without preheatingand stress relieving are preheating and stress relieving still required under ASME B31.8 paras.824.1 & 825.2?

Reply (4): Yes, para. B801 indicates that “if a paragraph appearing in Chapters I through VIIdoes not have a corresponding paragraph in this chapter, the provisions apply to sour gas servicewithout modification.”


Subject: Pipe bend at 30% SMYS or greater, Paras. 841.321, 841.33, and 851.51


File: 02-3938

Question: Does ASME B31.8 address field bending of pipe after hydrostatic testing?

Reply: No.

I-5

ASME B31.8 INTERPRETATIONS

VOLUME 12

Replies to Technical Inquiries February 1,1999 Through June 30,2001


It has been agreed to publish intepretations issued by the B31 Committee concerning B31.8 as part of the update service to the Code. The interpretations have been asssigned numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda at the time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code may have superseded the reply.

These replies are taken verbatim from the original letters, except for a few typographical and editorial corrections made for improved clarity.

ASME procedures provide for reconsideration of these interpretations when or if additional information that the inquirer believes might affect the interpretation is available. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.

55

B31.8 Subject . B31.8-1989 Edition. Certification of a Listed Material to Another Listed

Specification ........................................................... 831.8-1995 Edition. Para . 842.431(g), Direct Burial . . ....................... B31.8-1995 Edition. Para . A843.1, Wave and Current Conditions . . . . . . . . . . . . . . . . . . E31G and 831.8-1995 Edition. Para . @1.113(b), Additional Requirements far Nominal

Wail Thickness t in Para . 841.1 1 ........................................... Para . 841.11(a), Design Factor ............................................... Para . 841.11(c)(2) ......................................................... Paras . 854.1(c) and 854.1(~)(5), Requirements for Class Location Change Study . . . . . . Table 841.1 14B. Design Factor for Steel Pipe Construction ....................... Utilization of Duplex Stainless Steel ..........................................

Interpretation

12-4 12-5 12-3

12-2 12-7 12-8 12-1 12-6 12-9

File .

B31-94-048 B 3 5 1-98-01 B3 1-98-021

B31-95-029 E3 1-97-058 B3 1-99-019 B 3 1 0 1-98-0 B31-99-031 B31-95-030

56

B31.8 Interpretations Vol. 12 12-1, 12-2, 12-3


Subject: Paras. 854.1(c) and 854.l(c)(5), Requirements for Class Location Change Study


File: B31-98-010

Question (1): If the location class changes from Class 1 to Class 4, is a study required under para.

Reply (1): Yes.

854.1(c)?

Question (2): Are fences and concrete barriers installed along the pipeline within the meaning of “physical

Reply (2): No.

barriers” in para. 854.1(~)(5)?

Question (3): Does para. 854.l(c)(5) require a “risk assessment study”?

Reply (3): No. It is up to the owner/operator to determine what types of studies are needed to meet the requirements.


Subject: B31G and B31.8-1995 Edition, Para. 841.1 13(b), Additional Requirements for Nominal Wall Thickness t in Para. 84 1.1 1


File: B31-95-029

Question (1): Can B31G be used to evaluate pipe based on remaining wail thickness for corrosion that

Reply (1): B31G is not applicable to new construction covered under the B31.8 Code.

has occurred during the installation stage?

Question (2): Can para. 841.113(b) be used as criteria for evaluating this corrosion?

Reply (2): No. The B31.8 Section Committee is currently reviewing the Code to determine whether corrosion under the situation you describe should be addressed.


Subject: B31.8-1995 Edition, Para. A843.1, Wave and Current Conditions


File: B31-98-021

Question (I): Is it practical to determine the most unfavorable expected combination of wave and current

Reply (1): Yes.

conditions?

Question (2): If so, how?

Reply (2): The ASME B3 1.8 Committee is limited strictly to the interpretation of the rules. ASME does not act as a consultant on the general application or on the understanding of the Code rules.

57

12-4, 12-5, 12-6 831.8 Interpretations Vol. 12


Subject: B31.8- 1989 Edition, Certification of a Listed Material to Another Listed Specification


File: B3 1-94-048

Question: Does the B31.8 Code address the certification of a listed material to another listed material

Reply: No.

specification by a service centerlprocessor?


Subject: B31.8-1995 Edition, Para. 842.431(g), Direct Burial


File: B31-98-015

Question (I): Is para. 842.431(g) an obligatory requirement for the design execution of 4 bar, direct

Reply (1): No. burial, gas plastic piping systems, in order to comply with the B31.8 Code?

Question (2): In case para. 842.431(g) is obligatory, can DEPA utilize in plastic pipe systems the digital mapping Geographic Information System (GIS) and pipe routing, indicating post marks instead of electronically conductive wire to satisfy the B3 1.8 Code requirements?

Reply (2): See reply to Question (1) above. I


Subject: Table 841.1 14B, Design Factor for Steel Pipe Construction


File: B31-99-031

Question (1): Per Table 841.1 14B. does a gas pipeline (which is covered by B31.8) that skirts a compressor station facility just inside the fence of the facility, but is not associated with the compression process within the facility and exterior to the station emergency shutdown system, need to be designed using a 0.5 or 0.4 design factor?

Reply (1): No.

Question (2): If the answer to Question (I) is no, if the location class allows, and if it is not a fabricated

Reply (2): Yes.

assembly, is a 0.72 design factor acceptable?

Question (3): Is a nitrogen gas pipeline covered by the B31.8 Code?

Reply (3): No.

Question (4): If the answer to Question (3) is no, is it because nitrogen is an inert gas and use of B31.8 for the design of nitrogen gas pipeline will be more stringent than necessary?

Reply (4): No. (

58

B31.8 Interpretations Vol. 12


Subject: Para. 841.1 l(a), Design Factor


File: B31-97-058

Question: For pipe produced in accordance with a specification approved in B31.8, can t in the design formula be adjusted above nominal if the wail thickness is guaranteed to be greater than the minimum allowed by the specification?

Reply: No.


Subject: Para. 841.11(~)(2)


File: B31-99-019

Question: My analysis indicated the AIS1 constant should be 0.0339 for a full-size specimen. The B31.8 Code constant is 0.0345. Would the B31.8 Section Committee consider reviewing the derivation of this constant in the Code?

Reply: Yes.


Subject: Utilization of Duplex Stainless Steel


File: B31-95-030

Question: Does B31.8 allow the utilization of duplex stainless steel pipe?

Reply: Yes. Please see paras. 802 and 811.

59

STD-ASME 831.8 INT NO*LL-ENGL 3999 0759670 Ob37250 OT7

ASME B31.8 INTERPRETATIONS NO. 11

Replies to Technical Inquiries September 1,1993, Through January 31, 1999


It has been agreed to publish intepretations issued by the B31 Committee concerning B31.8 as part of the update service to the Code. The interpretations have been asssigned numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda at the time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code may have superseded the reply.

These replies are taken verbatim from the original letters, except for a few typographical and editorial corrections made for improved clarity.

ASME procedures provide for reconsideration of these interpretations when or if additional information that the inquirer believes might affect the interpretation is available. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.

41

L999

B31.8

Subject

0759670 ObL7251 T33

Appendix F. Extruded Headers ............................................... Clarification of Specified Strength of Fittings ................................... Code Applicability ......................................................... Design of Slug Catchers .................................................... Earthquake Design ......................................................... Extruded Pipe ............................................................ Mill Certificaies ........................................................... Para . 81 l.l(d), Use of Aluminum Pipe ........................................ Paras . 826.1 and 826.2. Inspection and Testing Welds ............................ Para . 83 1.32. Special Fittings ................................................ Para . 831.373, Minimum Design Metal Temperature ............................. Para . 833, Stresses from External Loads. ...................................... Para . 833. Combined Stress Calculations ....................................... Para . 840.42, Additional Protective Devices .................................... Paras . 841.1 14(b) and 841.854, Change in Location ClasSlRoad Crossing ............ Para . 84 I . 121. Fabricated Assemblies ......................................... Para . 841.231, Bends ....................................................... Para . 841.24. Notches ...................................................... Para . 841.244, Arc Burns ................................................... Para . 842.51,Tie-Ins ....................................................... Para . 851.43(d), Permanent Field Repair of Leaks and Non-Lcaking Corroded Areas .................................................................

Para . 856.1, Reconversion of Steel Pipe ....................................... Para . A842.221, Corrosion Allowance ......................................... Para . A842.223, Combined Stress ............................................ Safety Comdor for Cas Pipeline ............................................. Table A842.22, Basic Design Factors .........................................

Interpretat ion

I 1-25 11-15 11-5 11-7 I 1-26 11-22 I 1-23 11-14 11-4 11-16 1 1 - 1 1 11-1 11-9 I 1-20 11-6 11-17 11-18 11-3 11-2 11-13

11-12 11-8 11-19 11-10 I 1-24 11-21

File

B3 1-96-042 831-95-039 B3 1-94-060 B3 1-96-038 B3 1-96-005 B31 -94-002 B3 1-97-023 B 3 1 1-94-06 B3 1-95-033 B3 1-96-003 B3 1-94-025 B3 1-94-046 B31 -94-052 B 3 2 1-97-01 B3 1-95-049 B3 1-97-010 8 3 1-97-016 B3 1-94-050 8 3 1-94-049 B3 1-94-026

B3 1-96-004 8 3 1 1-94-05 B31-97-011 B3 1-95-040 B3 1-97-057 B3 1-97-034

43

Previous page is blank

~

B31.8 Interpretations No. I I 11-1, 11-2, 11-3


Subject: ASME B31.8-1995, Para. 833, Stresses from External Loads

Date Issued: April 20, 1995

File: B3 1-94-046

Question (1): Is para. 833 applicable to above ground piping only, or can it be applied to buried piping

Reply (1): Paragraph 833 applies only to above ground piping.

as well?

Question (2): If para. 833 is applicable only to above ground piping, what is the proper method of combining stresses due to external loads on buried piping, and what are the acceptable limits of these stresses?

Reply (2): The B3 1.8 Code does not address combined stresses for buried pipelines.


Subject: ASME B31.8-1995, Para. 841.244, Arc Bums


File: B3 1-94-049

Question: For a series of pipe stringers operating below 40% of SMYS, the 20% solution of ammonium persulfate test on ground out arc burned mas shows blackened spots indicative of metallurgical notches. If ultrasonic testing shows that the remaining wall exceeds the minimum wall strength or if the pipe is rehydrostaticaily tested, would this pipe be suitable for gas transmission under the B31.8 Code?

Reply: The B3 1.8 Code does not address the treatment of arc bums on pipe operating at a hoop stress less than 40% of the SMYS.


Subject: ASME B3 1.8-1995, Para. 841.24, Notches


File: B3 1-94-050

Question: ASME B3 1.8, para. 841.24 required that “notches” must be prevented, eliminated, or repaired in pipelines and mains to operate at a hoop stress of 20% or more of the specified minimum yield strength. Does this requirement also apply to metallurgical notches?

Reply: Yes. The B3 1.8 Code does not make a distinction between “geomemc notches” and “metallurgical notches.”

45 Previous page is blank

11-4, 11-5, 11-6 B31.8 interpretations No. I l


Subject: ASME B31.8-1995, Paras. 826.1 and 826.2, Inspection and Testing Welds


File: B31-95-033

Question: Hoop stresses are used to determine if qualifications of procedures and welders shall be in accordance with para. 823.1 or 823.2. Should hoop stress be similarly used to determine if weld inspections and/or tests of welds shall be in accordance with para. 826.1 or 826.2?

Reply: Yes.

Interpretation: 1 1-5

Subject: ASME B3 1.8- 1992, Code Applicability


File: B3 1-94-060

Question: Does ASME B31.8-1992 apply to the design and fabrication of a barge to be used for the

Reply: No.

transportation of compressed natural gas?


Subject: ASME B31.8-1995, Paras. 841.1 14(b) and 841.854, Change in Location Class/Road Crossing


File: B3 1-95-049

Question (1): Does the Code address changes in design factor after a pipeline is constructed?

Reply (1): No.

Question (2): Does Table 841.114B apply when a road is built over or parallel to an existing pipeline?

Reply (2): No.

Question (3): Does the Code identify the limits beyond the pavement proper that the design factors for

Reply (3): No.

road crossings in Table 841.1 14B must apply?

Question (4): Does the Code define the distance from the edge of the road where the design factors for

Reply (4): No.

“parallel encroachment” in Table 841.1 14B must apply?

46

STDmASME 631.8 INT NO.11-ENCL 1999 II 0759b70 Ob17254 742

B31.8 Interpretations No. 11 11-7, 11-8, 11-9, 11-10


Subject: ASME B31.8-1995, Design of Slug Catchers


File: B31-96-038

Question: Would the B3 1.8 Code be applicable for the design of a slug catcher installed in a processing plant inlet receiving gas from a pipeline that contains free liquids?

Reply: Please see para. 802.1 1 for applicability of your situation.


Subject: ASME B31.8-1992, Para. 856.1, Reconversion of Steel Pipe


File: B3 1-94-05 1

Question: Does para. 856.1 of ASME B31.8-1992 apply in any way to the re-conversion of a steel

Reply: No.

pipeline from gas transportation back to liquid transportation, the original function of the pipeline?


Subject: ASME B31.8-1995, Para. 833, Combined Stress Calculations


File: B3 1-94-052

Question: Do the requirements of para. 833 apply to buried pipe?

Reply: No. Please see para. 832.1.


Subject: ASME B3 1.8- 1995, Para. A842.223, Combined Stress


File: B3 1-95-040

Question (1 1: Is the word “longitudinal” correct in the last two sentences of para. A842.223?

Reply (1): No.

Question (2): If the word “longitudinal” is incorrect in these two sentences, should the word “combined” replace “longitudinal” in either or both sentences?

Reply (2): Yes, in both sentences.

47

11-11, 11-12, 11-13 631.8 Interpretations No. 11


Subject: ASME B31.8-1995, Para. 831.373, Minimum Design Metal Temperature


File: B31-94-025

Question: When a closure head is designed to the requirements of ASME B3 1.8, is the minimum design metal temperature determined by ASME Section VIII, Division 1, UG-20 including the requirements of UCS-66 when appropriate, or is the MDMT established under the provisions of 8 3 I .8?

Reply: The B31.8 Code does not utilize the term “minimum design metal temperature” or define a similar term with the same meaning.


Subject: ASME B3 1.8-1992, Para. 851.43(d), Permanent Field Repair of Leaks and Non-Leaking Corroded Areas


File: B31-96-004

Question: The purpose of this Inquiry is to clarify my understanding of the method of repair referred to in para. 851.43(d). Surely if a nipple is welded over a small leak “to vent gas while welding” there is a possibility that the gas will ignite when the welding arc is struck, thereby causing a hazardous situation. If the leak were plugged with a tapered piece of wood, I could accept the philosophy behind this kind of repair.

Reply: This is an established and widely accepted practice for repairing small leaks. The gas is intentionally ignited and kept burning during the procedure, thus preventing an explosive mixture from developing.


Subject: ASME B31.8-1995, Para. 842.51, Tie-Ins

Date Issued: December 3 1, 1997

File: B3 1-94-026

Question: When it is necessary to make a field repair to a damaged or defective portion of plastic pipe by cutting out and replacing a cylinder as required by paras. 842.45 and 852.52, is this the same as a tie- in section as described in para. 842.5 l and therefore exempted from testing requirements except for testing the tie-in joints?

Reply: No. The section of pipe installed as a replacement of a damaged or defective portion of plastic pipe is not the same as a tie-in section as described in para. 842.5 1.

48

STD-ASME B31.8 INT NO*LL-ENGL 1999 E 0759670 Ob37256 515 II

B31.8 Interpretations No. 11 11-14, 11-15


Subject: ASME B31.8-1995, Para. SIl.l(d), Use of Aluminum Pipe


File: B31-94-061

Question (1): Does the reference to aluminum structure in Appendix K mean that aluminum pipe is

Reply (1): No.

qualified for use by the rules of B3 1.8?

Question (2): If not, can aluminum pipe be qualified for use by the provisions of 81 l.l(d)?

Reply (2): Yes.

Question (3): If the reply to Question (1) or (2) is yes, must the pipe be manufactured in accordance

Reply (3): No.

with ASTM (or equivalent) specification?

Question (4): If the reply to Question (1) or (2) is yes, do the requirements in Chapter II apply?

Reply (4): No.

Question (5): If the reply to Question (1) or (2) is yes, do the welding requirements in Chapter IV apply?

Reply (5): No.


Subject: ASME B31.8-1995, Clarification of Specified Strength of Fittings

Date Issued: December 3 1. 1997

File: B3 1-95-039

Question: Does ASME B31.8 allow a SMYS of 42,000 psi to be used for ASTM A 234 Grade WPB fittings on the basis of materials tests?

Reply: No. The specified minimum yield strength properties are established by the applicable component material, and product form specifications. Refer to para. 83 I .3 for applicable fitting specifications. Refer also to Appendices B and C for applicable material and product form specifications.

49

11-16, 11-17, 11-18 B31.8 Interpretations No. 11


Subject: ASME B3 1.8-1 995, Para. 83 1.32, Special Fittings


File: B3 1-96-003

Question: According to the stipulation of para. 831.32, “When special cast, forged, wrought, or welded fittings are required to dimensions differing from those of regular shapes specified in applicable American National and MSS Standards, the provisions of para. 801.4 shall apply.” In fact, the para. 801.4 does not exist in the Code. What shall one do while using nonstandard-dimension fittings?

Reply: ASME B3 1.8- 1995 states, “...the provisions of para, 83 1.36 shall apply.”


Subject: ASME B31.8-1995, Para. 841.121, Fabricated Assemblies

Date Issued: December 3 1 , 1997

File: B31-97-010

Question: As defined in para. 841.121, are permanent above ground facilities designed to launch and

Reply: Yes.

receive pipeline pigs considered fabricated assemblies?


Subject: ASME B31.8-1995, Para. 841.231, Bends


File: B31-97-016

Question (1): When para. 841.23 l(b) expresses maximum deflection in an arc length equal to the outside diameter, does it mean that bends shall be made minimum every single length equal to the outside diameter?

Reply (1): No. See para. 841.231(c).

Question (2): Is it possible that the requirements of ASME B31.8 specify clearly the minimum distance between cold bends as a function of the pipe outside diameter, wall thickness, yield strength, or any other parameters?

Reply (2): No.

50

B31.8 Interpretations No. 11 11-19, Ii-Za, 11-21


Subject: ASME B31.8-1995, Para. A842.221, Corrosion Allowance


File: B31-97-011

Question (1): Does the nominal wall thickness in the formula in para. A842.221 include corrosion

Reply (1): No.

allowance?

Question (2): Does the formula in para. A842.221 restrict the use of corrosion allowance in designing offshore pipelines?

Reply (2): No.


Subject: ASME B31.8-1995, Para. 840.42, Additional Protective Devices


File: B31-97-012

Question: In an area where the concentration of people has increased so the area has changed from a Location Class 1 to a Location Class 3, is it possible to instail additional protective devices such as automatic shutdown valves in the line to seal off that portion of the line that was designated Class 3 and reclassify the line to a Location Class 2 on the basis that these additional safety measures would be an alternative to derating the pipe or installing heavier wail pipe?

Reply: No.

Interpretation: 11 -21

Subject: ASME B31.8-1995, Table A842.22, Basic Design Factors


File: B3 1-97-034

Question (1): We inquire of your Committee the rationale of limiting the basic design factor for submarine pipelines to a universal value of 0.72.

Reply (1): The ASME B31.8 Committee is limited strictly to interpretation of the rules. ASME does not act as a consultant on the general application or on the understanding of the Code rules.

Question (2): Would the Committee consider a basic design factor of 0.80 to be appropriate for offshore

Reply (2): No.

pipelines?

SI

11-25 11.23, 11-24 B3 1.8 Interpretations No. 1 I


Subject: ASME B31.8-1992, Extruded Pipe


File: B3 1-94-002

Question: In Table El of the B3 I .8- 1992 Edition, which stress intensification factors apply for extruded

Reply: The appropriate factors are those shown for extruded welding tee unless extrusions meet

outlets covered in Appendix F?

requirements of a welding tee per ANSI B 16.9.


Subject: ASME B3 1.8-1995, Mill Certificates


File: B3 i -97-023

Question: Does ASME B31.8 require mill (material) certificates (chemical composition) for line pipe

Reply: No.

and its components to be provided as part of the specification?


Subject: ASME B3 1.8-1995, Safety Corridor for Gas Pipeline


File: B3 1-97-057

Question: Does the ASME B3 1.8 Code define the minimum clearance between a pipeline and a building

Reply: No.

intended for human occupancy? That is, does it specify a “safety corridor?”

52

B3 1.8 Interpretations No. I l 11-25, 11-26


Subject: ASME B31.8-1995, Appendix F, Extruded Headers


File: B31-96-042

Question (1): May a portion of an extruded header located outside of the zone of reinforcement have a thickness less than T, but greater than or equal to t, as defined in Figures 3 and 4 of Appendix F?

Reply (I): ASME B3 1.8- 1995 is titled Gas Transmission and Distribution Piping Systems. Appendix F of ASME B31.8-1995 is intended as a nonmandatory guide to engineers using the Code in their day-to- day workings on gas piping systems. A manufacturer of fittings should be designing fittings to the codes written specifically for that purpose: ASME B16.5 and MSS-SP75.

Question (2): Do the dimensions of the reinforced zone as defined in Figures 3 and 4 of Appendix F apply in a plane transverse to the axis of the run or carrier pipe?

Reply (2): ASME B31.8- 1995 is titled Gas Transmission and Distribution Piping Systems. Appendix F of ASME B31.8-1995 is intended as a nonmandatory guide to engineers using the Code in their day-to- day workings on gas piping systems. A manufacturer of fittings should be designing fittings to the codes written specifically for that purpose: ASME B16.5 and MSS-SP75.


Subject: ASME B3 1.8- 1995, Earthquake Design


File: B3 1-96-005

Question (1): Does ASME B31.8-1995 have any requirements or guidelines for earthquake design or

Reply (1): No.

safety verification of buried pipelines?

Question (2): Does ASME B31.8-1995 have any requirements relating to the use of seismic safety valves

Reply (2): No.

to be used in urban areas?

53

0757670 0544737 453


Replies to Technical Inquiries September 1, 1992, Through August 31, 1993

Interpretations 10-1 Through 10-1 1

It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8 as part of the update service to the Code. The interpretations have been assigned interpretation numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda at the time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code may have superseded the reply. The interpretations are not part of the Code or the Addenda.

These replies are taken verbatim from the original letters, except for a few typographical and editorial corrections made for the purpose of improved clarity.

ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certiQ,” “rate,” or “endorse” any item, construction, proprietary device, or activity.

33

0759b70 0544718 39T =

831.8 interpretations No. 10 10-1, 10-2, 10-3


Subject: ASME B31G-1991


File: B31-92-052

Question: Does ASME B31G-1991 Manual for Determining the Remaining Strength of Cor- roded Pipelines cover all of the ASME B31 Codes for Pressure Piping?

Reply: No. ASME B31G-1991 covers only ASME B31.4 Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols; ASME B31.8 Gas Trans- mission and Distribution Piping Systems; and ASME B31.11 Slurry Transportation Piping Systems.


Subject: ASME B31.8 1989 Edition, Duplex Stainless Steels


File: B31-91-026

Question: Is the use of duplex stainless steel, such as ASTM A 790 Grade S31803, permitted by the rules of ASME B31.8?

Reply: No.


Subject: ASME B31.8-1989 Edition, Para. 831.41(c) and Fig. F5, Reinforcement of Welded Branch Connections


File: B31-92-011

Question (1): Is there an inconsistency between the definition of d as specified in ASME B31.8- 1989 Edition, para. 831.41(c) and ASME B31.8-1989 Edition, Fig. F5?

Reply (1): Yes. The correct definition ford is “the length of the finished opening in the header wall measured parallel to the axis of the run” as shown in para. 831.41(c). The definition of d in Fig. F5 is being corrected.

Question (2): Does ASME B31.8-1989 Edition include branch connections by insertion?

Reply (2): No.

35

10-4, 10-5

m 0759670 0544719 226 m

B31.8 Interpretations No. 10


Subject:


ASME B31.8-1989 Edition, Para. 840.2, Location Class 4

File: B31-92-012, B31-92-044, B31-92-045, B31-92-046

Question: Does ASME B31.8-1989 Edition provide a numerical index for the description of ?multistory buildings are prevalent? and ?traffic is heavy or dense? as stated in ASME B31.8-1989 Edition, para. 840.2?

Reply: No.


Subject: ASME B31.8-1989 Edition, Paras. 840.2 and 845.4


File: B31-92-053

Question (1): Does ASME B31.8-1989 Edition state whether to use Division 1 or Division 2 in gas pipelines regions classified as Location Class l ?

Reply (1): No. The choice is made by the operating company.

Question (2): Does ASME B31.8-1989 Edition address the condition prescribed in para. 845.411 in sections of pipeline classified as Division 1 assuming an internal pressure that produces a hoop stress equivalent to 80% of the specified minimum yield strength?

Reply (2): No.

36

831.8 Interpretations No. 10

0757670 0544720 T 4 8

10-6,lO-7


Subject: ASME B31.8-1989 Edition, Platform Piping


File: B31-92-054

Question (1): From two wellhead platforms, a 6 in. test line from a test manifold and an 18 in. production line from a production manifold transport gas to their respective separators on a pro- ductionhtility platform. These lines are installed on connecting bridges via a support platform. Is the ASME B31.8-1989 Edition appropriate for the design of these lines crossing the connecting bridges?

Reply (1): No. Per para. 802.13(f), the Code does not apply to flow lines between wellhead and separator.

Question (2): May the ASME B31.8-1989 Edition be extended to design temperature below -20°F [para. 802.13(b)] once the impact tests at the lowest design temperature are accepted according to specified requirements?

Reply (2): No, per para. 802.13(b), the Code does not apply to piping with metal temperatures below -20°F.

Question (3): Is the design factor F = 0.6 acceptable for these lines (para. 841.122) [reference Question (i)]?

Reply (3): The ASME B31.8-1989 Edition does not apply to these lines.


Subject: ASME B31.8-1989 Edition, Paragraph 827


File: B31-92-055

Question: (1): Does ASME B31.8, para. 827 allow only repair of defective welds in accordance with API 1104?

Reply (1): No. Para. 827 also allows the removal of the defective weld.

Question (2): Under para. 827, are welding procedures and welders qualified in accordance with the ASME BPV Code, Section IX per para. 823.2 also acceptable.

Reply (2): Yes. Welding procedures and welders qualified per para. 823.2 are acceptable to repair defective welds in accordance with API 1104.

37

0759670 0544723 984 =

10-8, 10-9, 10-10 831.8 Interpretations No. 10


Subject: ASME B31.8-1989 Edition, para. 831.6, Calculation of Extruded Outlets


File: B3 1-92-047

Question (1): For an extruded outlet to meet the rules of ASME €331.8-1989 Edition, para. 831.6, must the actual thickness of the run wall T, be essentially a constant thickness over the entire run pipe reinforcement zone?

Reply (1): Yes. If the run pipe wall thickness varies, then the T, used for para. 831.6 area replacement calculations shall be the minimum thickness found in the run pipe reinforcement zone.

Question (2): For an extruded outlet to meet the rules of para. 831.6, must the width of the reinforcement zone outside the branch wall, rl - d/2, be constant?

Reply (2): Yes.

Note: If the rules of para. 831.6 are not met, the extruded outlet may be qualified in accordance with para. 831.36.


Subject: ASME B31.8-1989 Edition, Paras. 831.11 and 831.21(a), Use of API 6A Flanges With API 6A Valves


File: B31-93-019

Question: In using a flanged valve per M I 6A (permitted by para. 831.11) may weld neck line pipe flanges per API 6A be used to mate to the valve, even though API 6A flanges are not listed in para. 831.21(a)?

Reply: Yes.

Interpretation: 10.10

Subject:


ASME B31.8-1989 Edition, Para. 841.11, Allowance for Thread Depth

File: B3 1-93-020

Question: In para. 841.11, should the nominal wall thickness be reduced by the nominal thread depth (dimension h of ANSI/ASME B1.20.1, or equivalent)?

Reply: Yes. See also para. 841.113(b).

38

0759670 0544722 810

631.8 Interpretations No. 10 10-11

Interpretation: 10-1 1

Subject: ASME B31.8-1989 Edition, Para. 841.221, Use of MI 5CT Casing and Tubing for Pipeline Construction


File: B31-93-021

Question: Per para. 811.221, may t u h g or casing per API CT be used for pipeline construction provided weldability is not an issue (threaded connections are used rather than welded connections) and provided operating temperatures are such that ductility is equivalent to other materials which are referenced in ASME B31.8?

Reply: Yes.

39

ASME B 3 L * B A 93 0759670 0535738 177

ASME B31.8

INTERPRETATIONS NO, 9


Interpretation 9-1



ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activiv.

29

ASME B31.8A 93 W 0759670 0535739 003


Interpretation: 9-1

Subject: Paragraph 841.231, Wrinkle Bends


File: B31-92-009

Question (1): First of all, please acknowledge if it is correct that ASME can give answers to any question on ANSI B31.8 since ANSI B31.8 has been developed by one of ASME’s committees.

Reply (1): This interpretation originates from the B31.8 committee directly and is in full accordance with the ASME policy on inquiries.

Question (2): ANSI B31.8, para. 841.231(a), states “all bends shall be free from buckling ...” Please advise us of the definition of buckling and how buckling is different from wrinkle bends in para. 841.231(f).

Reply (2): There is no definition of buckling in B31.8. Paragraph 841.231(a) is intended to mean bends other than wrinkle bends.

Question (3): ANSI B31.8, para. 841.231(f) states: “Wrinkle bends shall be permitted only on systems operating at less than 30% of the specified minimum yield strength. When wrinkle bends are made in welded pipe, the longitudinal weld shall be located as nearly to 90 deg. with the top of the wrinkle as conditions will permit. Wrinkle bends with sharp kinks shall not be permitted. Wrin- kles shall have a spacing not less than the distance equal to the diameter of the pipe measured along the crotch. On pipe NPS 16 and larger, the wrinkle shall not produce an angle of more than l’/z deg. per wrinkle.”

(a) What is the definition of “wrinkle bends”? Is it wrinkles in bends which happen to exist unavoidably on intrados of the bends during the bending process, or is it one kind of bending method such as hot bend and cold bend?

(b) What is the definition of “crotch”? Could you explain how to measure “the diameter of the pipe measured along the crotch” by a drawing?

(c) It seems to be practically difficult to measure an angle of wrinkle. Could you recommend the method of measuring the angle of a wrinkle?

(d) On pipe NPS 16 and larger, there is a permitted tolerance for the angle per wrinkle. How is it in the case of pipe under NPS 16?

(e) Would you acknowledge the following specific case? “Pipe bend of material API 5L X46 seamless pipe can be permitted on systems operating at 1,250 psi even though it has wrinkles on intrados, if wrinkles meet the tolerances of spacing and angle specified in para. 841.231(f).” We believe the above is correct, as 1,250 psi is less than 30% of the minimum yield strength of X46 pipe (1,250 psi e 46,000 psi x 30% = 13,800 psi).

Reply (3): (a) A wrinkle bend as used in B31.8 is a bend in which the wrinkles are produced intentionally

to secure a shorter radius bend. The use of such bends is restricted to systems operating at less than 30% of SMYS. It is not related to the method of bending.

(b) The term crotch in para. 841.231 refers to the line along the inner curvature of a pipe bend.

(c) The geometry of the individual wrinkle is not specifically measured. The language refers to the total angle of the bend divided by the number of visible wrinkles, i.e., the change in bend angle per wrinkle.

9- 1

31

9- 1

ASME B3L.8A 93 m 0759670 O535740 825 m


(d) Paragraph 841.231 does not include a limit for the angle of a bend containing wrinkles in pipe smaller than NPS 16.

(e) The example stated is incorrect. The internal pressure has been confused with the specified minimum yield strength of the bend material. The maximum allowable operating pressure of the example bend depends on its thickness and is 30% of the pressure calculated according to the equation in para. 841.11.

Question (4): We understand that there is a separate standard ES-24 issued by PFI (Pipe Fabrication Institute) which specifies pipe bending methods, tolerances, processes, and material requirements. Please advise whether PFI Standard ES-24, para. 6.2, has any relation with ANSI B31.8, para. 841.231(f).

Reply (4): The PFI Standard ES-24 is not under the jurisdiction of ASME and we are unable to comment on how it is to be applied.

Question ( 5 ) : We would like to know whether there is any charge for your service.

Reply (5): There is no charge for the B31.8 Section Committee to provide interpretations of the B31.8 Code.

32 A4592A

9009275 0023099 097 =

ASME B31.8

INTERPRETATIONS NO. 8





ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.

23

m 9009275 0023100 b39

831.8 Interpretations No. 8 8-1, 8-2, 8-3

Interpretation: 8-1

Subject:


ASME B31.8, Para. 802, Applicability to Bypass Lines

File: B31-90-022

Question (1): Does ASME B31.8 apply to bypass lines around pipeline block valves?

Reply (1): Yes.

Question (2): Does ASME B31.8 apply to bypass lines which operate at temperatures as low as -46"C?

Reply (2): No. ASME B31.8 is not applicable to piping with metal temperatures below -20°F. [See para. 802.13(b).]

Interpretation: 8-2

Subject:


ASME B31.8, Para. 842.31, Plastic Pipe and Tubing Design Formula

File: B31-90-054

Question: Based on the attached derivation, should not the design formula for plastic pipe and tubing in para. 842.31 be

t P = 2 S X - (D - 2)

Reply: No. The formula found in the Code is based on an International Standards Organization (EO) equation. See ASTM D 2513.

Interpretation: 8-3

Subject: Design of Scraper Traps


File: B31-90-039

Question (1): Can a barrel of a scrapper trap be designed in accordance with ASME B31.8?

Reply (1): Yes.

Question (2): Can Appendix 24, ASME Section VIII, Division 1 be applied to the design for the end closure, when the clamp type connection is applied to the end closure of the scraper trap?

Reply (2): Yes.

25

8-4, 8-5, 8-6 B31.8 Interpretations No. 8

Interpretation: 8-4

Subject: ASME B31.8-1989 Edition, Paras. 826.1 and 841.322(c), Inspection of Welds and Testing After Construction


File: B31-90-068

Question (1): Does para. 826.1 exempt a piping system intended to operate at 1440 psig with material having a specified minimum yield strength of 35,000 psi from radiographic or other “DE?

Reply (1): Paragraph 826.1 would apply only if the hoop stress S, is less than 20% of the SMYS; otherwise, para. 826.2 would apply.

Question (2): Under para. 841.322(c), would pipelines and mains in Location Class 2 require testing at 1.25 times MOP regardless of hoop stress?

Reply (2): Yes.

Interpretation: 8-5

Subject: ASME B31.8-1989 Edition, Para. 833.2 and Appendix E, Stress Intersification Fac- tor


File: B31-91-003

Question: When determining the expansion stress as defined by para. 833.2, may the in-plane i, and out-plane i, intensification factors be used rather than the more conservative stress intensification factor i?

Reply: Yes. See Notes (1) and (2) of Table E-l.

Interpretation: 8-6

Subject: ASME B31.8-1989 Edition, Para. 831.31(b), Use of Buttwelding Fittings With Non- standard Dimensions


File: B31-91-014

Question: Do reducers or reducing outlet tees that have nonstandard dimensions and are in “partial compliance’’ with ANSI B16.9 or MSS SP-75 fulfill the requirements of ASME B31.8?

Reply: Yes, provided the requirements of paras. 801.2 and 831.32 are met.

26

m 9009275 0023302 401 m r

631.8 Interpretations No. 8 8-7, 8-8

Interpretation: 8-7

Subject: Paragraph 840.2(b) and Tables 841.114A and B, Definition of Location Class 1, Division 1


File: B31-91-018

Question: Table 841.114A, Basic Design Factor F, identifies a Location Class 1, Division 1, and an associated design factor 0.80. Table 841.114B, Design Factors for Steel Pipe Construction, lists the type of facility and the associated location class for pipelines, etc. Paragraph 840.2(b) is referenced.

I have Addenda through January 15, 1991 for the 1989 Edition. However, I cannot find any reference wherein Division 1 and Division 2 are differently defined for Location Class 1. Could you please point out the proper paragraph. I would appreciate it very much.

Reply: Paragraph 840.2(b) is being revised to include definitions of Location Class 1 Division 1 and Location Class 1 Division 2. The proposed definitions are presently going through the ASME approval process before publication.

Interpretation: 8-8

Subject: Welding Terminology


File: B31-91-009

Question (1): What is meant by “longitudinal joint factor E” of Table 841.1B?

Reply (1): In ASME B31.8a-1990 Addenda, the longitudinal joint rating factor is contained in Table 841.115A. The longitudinal joint factor is the term E in the design formula of para. 841.11(a) used to compensate for the characteristic strength of a weld seam in a pipe.

Question (2): What is the definition of “electric arc welding”?

Reply (2): Definitions of welding processes are contained in para. 804.243. The term “electric arc welding” is not defined. Both electric-fusion-welded pipe [para. 804.243(c)] and double sub- merged-arc-welded pipe [para. 804.243(e)] are produced using electric arc welding in which coa- lescence is produced by heating with a electric arc(s) between the metal electrode(s) and the work.

Question (3): What is meant by “joint efficiency”?

Reply (3): Joint efficiency is not defined even though para. 817.13(d) is titled “Joint Efficiency.” However, the terms “joint efficiency” and “longitudinal joint factor” mean the same thing.

27

~

= 9009275 0023040 334 =



It has been agreed to publish interpretations issued by the 831 Committee concerning 831.8 as part of the update service to the Code. The interpretations have been assigned interpretation numbers in chronological order. Each interpretation applies either to the latest Edition or Addenda at the time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code may have superseded the reply. The interpretations are not part of the Code or the Addenda.


ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not "approve," "certify," "rate," or "endorse" any item, construction, proprietary device, or activity.

19

831.8 Interpretations No.7 7-1, 7-2

Interpretation: 7-1

Subject : Hydrotest Preparation

Date Issued: June, 12, 1987

File: 531 -86-033

Question: May all joints, including welds, used in piping systems covered by ANWASME B31.1, ANWASME B31.3, ANSIIASME B31.4, ANSIIASME 631.8, ANSVASME B31.9, and ANSIIASME B31.11 be primed and painted prior to hydrotest?

Reply: Yes.

Note: This interpretation was inadvertently omitted from Interpretations No. 5, which includes interpretations issued from February I , 1987, through December 31 , 1988.

Interpretation: 7-2

Subject: Paras. 841 .I 1 (a) and 841 .I 21 (0, Mimimum Yield Strength


File: B31-89-022

Question: Is it permissible under the requirements of para. 841 .I 21 (0 in ANSI/ASME B31.8 to use an actual yield strength value that is less but not greater than the specified minimum yield strength as stipulated in the specification?

Reply: Yes.

21

7-3, 7-4

J -. ," "% -"?

9009275 0023042 L O 7


Interpretation: 7-3

Subject: Para. 823.22, Welder Qualification Test


File: B31-89-011

Question (1): Under the requirements of .ANSVASME B31.8, para. 823.22, is it permissible to test the welder to API 11 04 but ignore the results of tensile and nick-break tests?

Reply (I): No.

Question (2): Under the same paragraph in Question (11, is it permissible to test the welder to API 1104 but using only six bend tests instead of two tensile, two nick, and two root bend tests?

Reply (2): No.

Question (3): Under the same paragraph in Question (I), is it permissible to test the welder to API 11 04 but use Appendix C of ANSVASME 931.8 to test the straps?

Reply (3): No.

Question (4): If Reply (3) i s no, are there some other requirements than those questioned in (11, (21, and (3)?

Reply (4): Yes. Test the welder to the provisions of API I 1 04 including the guided bend tests.

Interpretation: 7-4

Subject: Para. 843.443, Setting of Pressure Relief Valves


File: 831 -89-01 4

Question: Under the requirements of ASME B31.8, para. 843.443, can a safety relief valve be set at any pressure between the maximum allowable operating pressure (MA0P)and 11 0% of the maximum allowable operating pressure for compressor station piping?

Reply: Yes. The safety relief valve can be set at any point which will assure the operating pressure of the compressor and discharge piping will not exceed the maximum allowable operating pressure by more than 10%.

22

’ m 9007275 002295b T 4 2 m

ASME B31.8

Interpretations No. 6 Replies to Technical Inquiries

April 1, 1989, Through August 31, 1989

It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8 as part of the update service to the Code. The interpretations have been assigned interpretation numbers in chronological order. Each interpretation applies to the latest Edition or Addenda at the time of issuance of the interpretation or the Edition or Addenda stated in the reply, Subsequent revisions to the Code may have superseded the reply. The interpretations are not part of the Code or the Addenda.


ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.

13

63 1.8 Interpretations No. 6

~ i 1 -

9009275 0022757 9 8 9

6-1, 6-2

Interpretation: 6-1

Subject: ANSI/ASME B31.8, Paras. 81 1.253(b) and (gil Qualification of Steel Pipe


File: B31-88-026

Question: For qualification of used steel pipe or unidentified new steel pipe for use at stress levels above 6000 psi, ANSI/ASME 831.8 specifies the following requirements (in addition to others):

(i) flattening test for pipes larger than NPS 2 [reference para. 81 1.253 (b)]; (i¡) yield-tensile ratio less than or equal to 0.85 [reference para. 81 1.253 (g)].

Can it be interpreted from the above that for new pipes ordered as per a ‘Code’ approved standard (e.g. API SL), the above requirements should be specified as additional requirements, in the event they are not mandatory requirements, for a particular type or grade of steel pipe?

Reply: No.

Interpretation: 6-2

Subject: ANSUASME 831.8, Requirements for Compressed Air Piping Systems


File: 831 -88-03 1

Question: Does ANSI/ASME 831.8 cover piping systems for compressed air systems, such as those used in industrial automation, robotics, and air driven tools?

Reply: No, You are directed to the Scope sections of 831.1 (para. 100.1.3), 831.3 [para. 300.1.l(b)], and B31.9 (para. 923.3.2) which may be suitable for your application. You may wish to also review the requirements of Chapter VI1 in B31.3 on nonmetallic pipe.

15

~

9009275 0022958 815

6-3, 6-4 83 1.8 Interpretations No. 6

Interpretation: 6-3 i

Subject: ANSI/ASME B31.8, Para. 802.13(f), Design of Flow Lines


File: B3 1-89-002

Question (i 1: ANSI/ASME B31.8'~ para. 802.1 3(f) states that this Code does not apply to flow lines between wellheads and traps or separators. Many flow lines in the oil field have been designed using the design formula from this Code under para. 841 -1 lía). What is the intent of this exclusion?

Reply (1 1: The original intent of excluding flow lines from B31.8 is unknown; however, the intent of 831.8 is to cover field gathering pipelines, transmission lines, and distribution systems. See Fig. 18, Appendix I.

Question (2): If 831.8 is not the appropriate Code for flow line design, what is?

Reply (2): See B31 Code Case 137, Piping Not Covered by Any ANSI/ASME 831 Section, for guidance.

Interpretation: 6-4

Subject: ANSI/ASME B31.8, Paras. 802.1 3(g) and 803.261, Exclusion from Scope- Instrument Piping


File: B31-88-028E

Question: Does ANSI/ASME 831.8 require that the pressure-containing portion of an in-line sensing device be designed, fabricated, examined, and tested in accordance with the rules of ANSI/ASME B31.8?

Reply: Yes.

16


Interpretation: 6-5

6-5, 6-6

Subject: ANSI/ASME B31.8, Para. 840.l(al, Maximum Allowable Stress for Buried Pipe Subject to Ground Movement


File: 83 1-89-01 2

Question: Under the requirements of ANSI/ASME B31.8, what is the maximum allowable stress for buried gas pipelines subject to movement at active ground faults?

Reply: The 831.8 Code does not specifically indicate the maximum allowable stresses in buried gas pipelines resulting from catastrophic events such as movement at fault crossings. See para. 840.1 (a).

Interpretation: 6-6

Subject: ANSI/ASME B31.8, Para. 843.51 1, Limits of Compressor Station Piping


File: 83 1-89-003

Question (1 1: Under the requirements of ANSI/ASME 831.8, what is the basis of using Type C construction for compressor stations?

Reply (1 ì: Table 841.1 5A.

Question (2 ) : Is Type C construction related to reciprocating compressor stations?

Reply (21: Type C construction applies to all types of compressor stations including reciprocating.

Question (3): What is the breakpoint for Type C construction?

Reply (31: The station suction and discharge valves if the station is located in Location Classes 1, 2, or 3. See para. 843.511.

Question (41: Under the requirements of ANSI/ASME 831.8 does compressor station piping, Type C, apply from the suction valve to the discharge valve?

Reply (4): Type C construction applies from the station (not the compressor unit) suction valve to the station (not the compressor unit) discharge valve. See para. 843.51 1.

17

~ ~~

= 9009275 0022960 473

6-7 B31.8 Interpretations No. 6

Interpretation: 6-7 i

Subject: ANSI/ASME B31.8, Para. 843.51 1 and Table 841.15A, Limits of Compressor Station Piping


File: B31-89-015

Question (1): Under the requirements of ANSI/ASME B31.8, Para. 843.51 1 and Table 841.15A, is Type C construction only limited up to the discharge valve of the individual compressor units, and Type B construction limited to the combined suction and discharge line of a compressor station?

Reply (1 1: No. Type C construction applies from the station (not the compressor unit) suction valve to the station (not the compressor unit) discharge valve.

Question (2): If new piping is added upstream of the discharge fire gate, of an existing compressor station for incorporation of gas cooling equipment, is such piping required to be of Type C construction?

Reply (2): Yes.

Question (3): Do the requirements of Para. 843.51 1 and Table 841.1 SA limit Type C construction to compressor stations having reciprocating compressor units, or do they include compressor stations having centrifugal compressors as well?

Reply (3): Type C construction applies to all types of compressor stations including reciprocating and centrifugal. 9

18

I 9009275 0022664 376 I

ANSI/ASME B31.8

1 nterpretations No. 5 Replies to Technical Inquiries

February 1 , 1987, Through December 31, 1988

It has been agreed to publish interpretations issued by the B31 Committee concerning 831.8 as part of the update service to the Code. The interpretations have been assigned interpretation numbers in chronological order. Each interpretation applies to the latest Edition or Addenda at the time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code may have superseded the reply. The interpretations are not part of the Code or the Addenda.


ASME procedures provide for reconsideration of these interpretations when or if additional info;- mation is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” ”certify,“ ”rate,” or “endorse” any item, construction, proprietary device, or activity.

E 9009275 0022665 202 9


Interpretation: 5-1

Subject: ANSI/ASME B31.8, 845.41 1, Overpressure of Corroded Piping Systems

Date issued: February 5, 1987

File: 63 1-86-038

Question: When a reduced Maximum Allowable Operatirig Pressure (MAOP) of a corroded piping system has been set equal to the safe maximum pressure determined in accordance with the methods of Appendix L, may the provisions of 845.41 1 of ANSI/ASME B31.8 be applied, where the piping system pressure relief or pressure limiting station(s1 prevent the pressure from exceeding the reduced MAOP plus 1 O%, or prevent the pressure from producing a nominal hoop stress greater than 75% of the specified minimum yield strength, whichever is lower?

Reply: The provisions of 845.41 1 of ANSI/ASME B31.8 may be applied because Appendix L provides a P? which may be less than the original design pressure or established MAOP. The P? would then become the new MAOP for purposes of determining the not-to-exceed pressure in 845.41 1. This not-to-exceed pressure is the lower of 110% of P? or the pressure which produces a hoop stress of 75% of SMYS based on the original nominal wall thickness.

5-1

7

5-2, 5-3 83 1.8 Interpretations No. 5

Interpretation: 5-2

Subject: ANSi/ASME 831.8, 841.1 23 and 854.1(c), Pipeline Reclassification


File: 83 1-86-039

Question (1): Why do the requirements in 841.123 of ANSI/ASME B31.8 call for all pipeline bridges in Class 1 areas to be of Type 8 construction?

Reply (1): See 841.13(a) of ANSI/ASME 831.8.

Question (2): Where changes in population index imply that road or river crossings would require to be classified with a higher construction type, would it be necessary to reduce the maximum permissible operating pressure or replace crossings with increased wall thickness, or would it be sufficient to retest the section hydrostatically to prove the integrity?

Reply (2): Class locations and population density indexes are defined in 840.2. Subparagraph 854.1 (c) indicates what items to study when the population density index increases. Paragraph 854.2 fully covers the alternatives available with respect to retesting, lowering the MAOP, or replacing pipe as a result of a population density index increase.

Question ( 3 ) : in 854.1 (cl the Code lists five areas to be considered in a study to reclassity a line. Is the Committee able to advise on more specific points or particular areas that should be reviewed or inspected, and the most critical points that require careful consideration when embarking on a reclassification study?

Reply (3): As a Code writing body, the 531.8 Section Committee is limited to interpreting the Code and cannot give advice on specific applications.

Interpretation: 5-3

Subject: ANSI/ASME 531.8, 846.1 l (d) and 846.21(c), Valves ai Offshore Platforms

File: €33 1-87-029


Question (1 1: Do the requirements of ANSI/ASME 631.8 specify a location for valves that are required to shut off the flow of gas to an offshore platform in an emergency?

Reply (1 1: No, only that valves or other components shall be provided to shut off the flow of gas to the offshore platform. See 846.1 1 (d).

Question (2): Do the requirements of ANSI/ASME 531.8 specify a location for blowdown valves?

Reply (2): No, only that each section of pipeline betweei? block valves can be blown down, aad blowdown piping shall be sized such that under emergency conditions the section of line can be blown down as rapidly as is practical. See 846.21(c).

8

631.8 interpretations No. 5

~~ ~ ~ ~ -

H 7009275 0022667 Oô5

5-4, 5-5

Interpretation: 5-4

Subject: ANSI/ASME 531.8, 841.1 1 (a), Steel Pipe Design Formula

File: 631 -87-030


Question: When determining design pressure for older pipelines in place and where pipe records are minimal, wouldn't the 24,000 psi valve be a sufficient downgrade for both the E and 5 factors found in design formula 841.1 1 (a) of ANSI/ASME 631.8?

Reply: No. See 81 1.253.

Interpretation: 5-5

Subject: ANSI/ASME 531.8, 833.4, Stress Calculations

File: 631 -86-037


Question (1 1: Paragraph 833.4 of ANSI/ASME 631.8 states that "The sum of 833.4(b) and (c) shall not exceed 75% of the allowable stress in the hot condition. . . ." An interpretation of this requirement is that (b)+(c) shall not exceed 54% of SMYS (75% of 72% for design factor = 0.72 1oca:ions). Does this reflect the intent of this section?

Reply (1): No. The sum of (b)+(c) cannot exceed 75% of SMYS. The longitudinal pressure stress (b) is limited by 841.1 1, SFT.

Question (2): Subparagraph 833.4 (cl of ANSI/ASME 531.8 includes "wind" as an occasional load component. Stresses resulting from wind induced vortex shedding on above ground pipelines has always been considered a fatigue load. This fatigue load is evaluated using fatigue load criteria, and not as an occasional wind load to be included under the requirements of 833.4k). i s this correct?

Reply (2): Yes.

9

5-6

~ - = 9009275 0022668 T L L

Interpretation: 5-6


Subject: ANSI/ASME 831.8, 833, Stress Calculations

File: 831 -87-01 6


Question (1): In evaluating expansion stress under ANSI/ASME B31.8, should both the thermal and pressure effects be considered? If not, which of the two and why?

Reply (1): Yes, but not together. Thermal effects should be considered in 833.3 while pressure effects should be considered in 833.4(b).

Question (2): Is axial force in a pipeline a component of the longitudinal pressure stress?

Reply (2): No. The longitudinal force resulting from pressure stress is one component of axial force in a pipeline.

Question (3): In 833.4 of ANSI/ASME B31.8, is it correct to assume that the intent is that the longitudinal pressure stress considers only the effects of pressure and that the longitudinal bendirìg stress considers external loads, both sustained and occasional? If not, what is the intent?

Reply (3): Yes. Bending stresses due to internal pressure should be considered in the longitudinai pressure stress [833.4(b)] and the external loads, sustained or occasional, should be considered in the longitudinal bending stress [833.4(c)], which are primary and not secondary.

.

10

B3 1.8 Interpretations No. 5

Interpretation: 5-7

Subject: ANSI/ASME B31.8, 833.4, Stress Due to Displacement

File: 831 -86-030


Question (1 ): A piping system is being designed from one offshore platform to another offshore platform via a connecting bridge as per ANSI/ASME B31.8 (classification of steel pipe construction Type Cl. Platforms are subject to severe deflections under extreme environmental conditions and their differential deflection is severe. Is this deflection effect on piping a part of the loads discussed under 833.4(c) (wind, etc.)?

Reply (1): No. Subparagraph 833.4k) is intended to limit the sum of longitudinal bending stresses resulting from externally applied “primary” loadings, from whatever source. It is not intended to apply to stresses resulting from self-limiting, secondary displacement strains. Wind and wave action that acts on the pipe itself is an externally applied “primary” loading and must be included in 833.4k). However, wind and wave action that i s applied to an offshore platform causes a predictable displacement of the platform which is limited by the design of the platform. Movement of the platform imposes displacements on the piping restraints and supports which is similar to thermal effects. These displacements must be included with thermal effects in flexibility and expansion analysis.

Question (2 ) : If so, can the allowable stress for 833.4(b) and (cl be increased to a higher value as per ANSI/ASME 631.4?

Reply ( 2 ) : No. There are no increases permitted in the allowable stresses specified in 833.3 and 833.4. ASME/ANSI B31.3 and B31.4 have no bearing on 833 of ANSIIASME 631.8.

Question (3): As per ASME/ANSi 631.3, the deflection effects are to be considered together with thermal effects for displacement stress range computation only. Does this apply to ANSi/ASME B31.8 stress range computation also?

Reply (3): Yes. Secondary stresses resulting from externally imposed fixed displacements should be included with the calculation of expansion stresses covered in 833.3 and 833.4(a).

Question (4): Occasionally some clients interpret that the expansion stress (secondary stress) as per ANSI/ASME 831.8 for construction type C shall not exceed 0.55. Does the allowable expansion stress require adjustment based on construction type?

Reply (4): No.

Questiori (5): Are there any adjustments to the allowable limits for the total longitudinal stress computed per 833.4a1, (b), and (cl to reflect the construction type?

5-7

Reply (5): The longitudinal pressure stress calculated in 833.4(b) must be adjusted for the construction type design factor.

11

~ ~ ~~ ~

9009275 0022629 2 7 1

ANSI/ASME B31.8 Interpretations No. 4

It has been agreed to publish interpretations issued by the 831 Committee concerning 831.8 as part of the update service. This supplement includes interpretations concerning B31.8 issued between January 1, 1986, and December 3 1, 1986. They have been assigned interpretation numbers in chronological order. Each interpretation applies to the latest Edition or Addenda at the time of issuance of the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code may have superseded the reply. The interpretations are not part of the Code or the Addenda.

These replies are taken verbatim from the original letters, except for a few typographical andeditorial corrections made for the purpose of improved clarity.

ASM E procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.

1

6 9009275 0022630 T93 - B31.8 Interpretations No. 4

interpretation: 4-1

Subject: Flexibility Factor and Stress Intensification Factor Tables


File: B3 1 -85 -03 O

Question (1 ): What is the difference between a “welding tee per ANSI B16.9” and an “extruded welding tee” as stated in Appendix D, Table D-1, of ANSI/ASME 831.3 and Appendix E, Table E-1, of ANSI/ASME B31.8?

Reply (1 1: A “welding tee per ANSI B16.9” complies with all requirements of ANSI B16.9. An “extruded welding tee” complies with the requirements of 304.3 of ANSI/ASME 831.3 or 831.41 and 831.6 of ANSI/ASME B31.8.

Question (2): Is the difference related to ANSI B16.9 dimensions as defined by ANSI/ASME B31.3 and ANSI/ASME 631.8?

Reply (2): No.

Question (3): Is the difference related to manufacturing?

Reply (3): ANSI 616.9 does not specify manufacturing methods.

Question (4): When a “welding tee per ANSI B16.9” does not meet the radius and thickness limits specified in Appendix D, Table D-1, of ANSI/ASME 631.3 or Appendix E, Table E-1, of ANSI/ASME 631.8, i s it permissible to use the flexibility characteristic h for an “extruded welding tee” provided r, 2 D, and T, < 1.5T?

4-1

Reply (4): Yes, provided the tee is formed by an extrusion process; otherwise it is the responsibility of the designer to determine the proper flexibility characteristic.

3

4 P

B

I 9009275 O022633 92T = 4-2

Interpretation: 4-2

Subject:

Date Issued:

826.2, NDE of Gas Compression Equipment

December 1 , 1986

File: 631 -85-023

~


Question (1): According to 826.2, what percentage of the butt welds in new packaged gas equipment shall be examined for use in Class 3 locations?

Reply (1): 10Oo/o if practical, but no less than 90% [see 826.2(b)(5)].

Question (2): If a gas compression package is designed and tested for use in a Class 3 location and is later relocated to a compressor station, what additional requirements apply?

Reply (2): None.

Question (3): A new section of piping i s added to existing gas compression equipment. What percentage of the new welding is required to be examined?

' i I

Reply (3): See Reply (1).

Question (4): If new piping is added to existing gas compression equipment, is it required that any of the existing welding be examined?

Reply (4): No, if it met the conditions of 826.2(b)(5). F

4

Interpretations No. 3 to ANSUASME 631.8

(This supplement is not part of ANSIIASME 831.8 or the Addenda. It is included for information only.)

It has been agreed to publish Interpretations issued by the B31 Committee concerning B31.8 as part of the subscription service. This supplement includes Interpretations concerning B31.8 issued between January 1, 1985, and June 30, 1985. They have been assigned interpretation numbers in chronological order. Each Interpretation applies to the latest Edition or Addenda at the time of issuance of the Interpretation. Subsequent revisions to the Code may have suspended the reply. Future versions of this supplement will cover inquiries issued over 1 year periods.


ASME procedures provide for reconsideration of these Interpretations when or if additional information is available which the inquirer believes might affect the Interpretation. Further, persons aggrieved by an Interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.


H 9009275 0022378 118

3-1, 3-2

Interpretation: 3-1

Subject: 845.243, Overpressure Protection for Fuel Gas Piping

Date issued: March 4, 1985

File: 83 1-84-0 1 O

Question: At a power plant, high pressure natural gas is delivered to a meter set assembly which includes two regulating valves in series that reduce the natural gas pressure to a level suitable for firing the boiler. Do these two regulating valves in series provide the overpressure protection required by the ANSUASME 831.1 Code?

Reply: As stated in Para. 100.1.2(c), the scope of the ANSVASME B31.1 Code includes only the piping downstream from the meter set assembly. The meter set assembly and the piping upstream are included in the scope of the ANSVASME B31.8 Code. Paragraph 845.243 of the 831.8 Code describes three suitable methods which may be used to regulate and limit the maximum safe value of the pressure delivered to the customer. The regulating valves, as described in this Inquiry, should be acceptable if they conform to one of the methods described in Para. 845.243.

Interpretation: 3-2

Subject: 825.2 and 825.3, Thickness to be Used to Determine Stress Relieving


File: B 3 1 -84-02 6

Question (1): A section of pipe having a wall thickness of less than 1: in. i s to be welded to a fabricated tee having a nominal wall thickness greater than 1; in. which has been tapered to match the wall thickness of the pipe. Is stress relieving required per 825.2 and 825.3 of ANSVASME B31.8?

Reply (1): Assuming the tee i s manufactured under the appropriate MSS specification, the taper in the wall thickness of the tee i s made in accordance with Appendix I of B31.8 and appropriate qualified welding procedures are employed, stress relieving is not required.

Question (2): At what specific location is the wall thickness to be measured when determining the need for stress relieving as required in 825.2 and 825.3 of ANSVASME B31.8?

Reply (2): The determining wall thickness is the maximum wall thickness of the pipe or fitting in the heat-affected zone of the weld joint.

3

3-3, 3-4 631.8 Interpretations NO. 3

Interpretation: 3-3

Subject: 822.1 (b) and Appendix I , Fig. 15, Acceptable End Preparations

Date issued: April 15, 1985

File: B3 1-84-036

Question: Does the joining of two equal strength pieces of pipe with unequal wall thickness, with the thicker piece being counterbored, meet the requirements of Fig. i5 of ANSVASME 631.8!

Reply: The weld configuration i s one of unequal wall thickness and equal strength as depicted in Fig. 15(b), with asterisk footnote, or with equal walls as in Fig. 14.

Interpretation: 3-4

Subject: 849.222, Installation of Gas Line Under Buildings


File: 83 1-85-007

Question: Gas piping i s installed beneath a building floor. Does 849.222(b) require that the portion of the piping under the building, but not necessarily the section outside the building, be encased in a gas tight conduit?

Reply: Yes.

4

= 9009275 0022362 850

Interpretations No. 2 to ANSVASME B31.8

(This supplement is not part of ANSI/ASME 831.8 or the Addenda. I t is included for information only.)

It has been agreed to publish Interpretations issued by the B31 Committee concerning 831.8 as part of the subscription service. This supplement includes Interpretations concerning B31.8 issued between Janu- ary 1, 1984, and December 31, 1984. They have been assigned Interpretation numbers in chronological order. Each Interpretation applies to the latest Edition or Addenda at the time of issuance of the Interpre- tation. Subsequent revisions to the Code may have superseded the reply. Future versions of this supplement will cover inquiries issued over 1 year periods.


ASME procedures provide for rensideration of these Interpretations when or if additional information is available which the inquirer believes might affect the Interpretation. Further, persons aggrieved by an Inter- pretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not ‘(tpprove,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.

1

- ~~

7009275 O022363 797 W

B3 1.8 Interpretations No. 2 2-1

Interpretation: 2-1

Date Issued: November 16,1984

Subject: Hoop Stresses in 841.32

File: 63 1-84-006

Question: To determine whether hoop stresses exceed 30% of the SMYS of pipe in 841.32 of ANSI/ ASME B31.8, shall the 0.30 factor be applied to the entire hoop stress formula given in 841 .I 1 (a)?

Reply: No. The 0.30 factor shall be applied to 2StlD. Factors F, E, and Tare not to be used in th i s case.

3

i

6

B31.8 - Cases No. 2

(The Cases are not part o f ANSIIASME 831.8 or its Addenda and are included for information only.)

A ?Case? is the oficial method of handling a reply to an Inquiry when study indicates that the Code wording needs clarification, or when the reply modifies the existing requirements of the Code, or grants permission to use new materials or alternate constructions.

It has been agreed to publish Cases issued by the 831 Committee concerning B31.8 as part of t h e subscription service to 831.8. The text of proposed new and revised Cases will appear in Mechanical Engineer- ing for public review. A notice will also appear in Mechanical Engineering when new and revised Cases are approved. The Cases will then appear with the next regularly scheduled Addenda to 831.8.

Foilwingthis t i t le sheet i s Case 142, which is related to all 831 Codes.

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CASES CODE FOR PRESSURE PIPING - B3 1

Case 142 Capacitor Dischar* Muthad of Wilding

Inquiry: May the capacitor discharge method of welding be used to temporarily attach thermocouples to pressure parts to measure metal temperature either when preheating or during postweid heat treatment, or both, of piping components for 631 construction and may this be done without performance and procedure qualification?

Reply: It is the opinion of the Committee that the capacitor discharge method of welding may be used for 831 construction to temporarily attach thermocouples directly to the pressure parts to measure metal temperature either when preheating or during post- weld heat treatment, or both, of piping components provided the thermocouple is removed and the area is visually examined in accordance with the applicable ANSVASME 831 Code requirements. Performance and procedure qualifications are not required.

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 345 East 47th Street, New York, N.Y. 10017

CASE 142 July 1984

This Case shall expire on July 31, I98 7 unless previously annulled or reaffirmed.

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Interpretations No. 1 to ANSI/ASME B31.8

(This supplement is not part of ANSIIASME 831.8 or the Addenda. It is included for information only.)

It has been agreed to publish Interpretations issued by the B31 Committee concerning B31.8 as part of the subscription service. This supplement includes Interpretations concerning B31.8 issued between January 1,1983, and December 31,1983. They have been assigned Interpretation numbers in chronological order. Each Interpretation applies to the latest Edition or Addenda at the time of issuance of the Inter- pretation. Subsequent revisions to the Code may have superseded the reply. Future versions of this supplement will cover inquiries issued over 1 year periods.

These replies are taken verbatim from the original letters, except for a few typographical and editorial corrections made for the purpose of improved clarity,

ASME procedures provide for reconsideration of these Interpretations when or if additional information is available which the inquirer believes might affect the Interpretation. Further, persons aggrieved by an Interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the Statement of Policy in the Code documents, ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.

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Interpretation: 1-1

Date Issued: March 2,1983

Subject:

File: 1622

Design Based on Inside Diameter

Question: Does ANSI/ASME 831.8 recognize and allow design based on inside diameter?

Reply: No.

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Interpretation: 1-2

Date Issued: March 2,1983

Subject: Pipe-Type Holders in 844

File: 1630

Question: According to 844.3 of ANSI/ASME B31.8, pipe-type holders should have a minimum clearance from fenced boundaries of site of 25 ft if maximum operating pressure is less than i000 psig, and 100 ft if pressure is 1000 psig or more. However, 844.1 of ANSI/ASME B31.8 also allows pipe-type holders to be installed in streets, highways, or in private rights-of-way not under the exclusive control and use of the operating company if the holders are designed, installed, and tested in accordance with the provisions of the Code applicable to a pipeline in the same location and operated at the same maximum pressure. Is it contrary to the requirements of ANSI/ASME B31.8 if a pipe-type holder, which is to be installed on site under the exclusive control and use of the operating company, does not have any clearance limitations from the fenced boundaries, but it i s designed, installed, and tested in accordance with the provisions of the Code applicable to a pipeline installed in the same location and operated a t the same maxim um pressure?

Reply: It is not intended that the additional requirements for clearance from fenced boundaries set out in 844.32(a) and (b) be applied to pipe-type bottle holders meeting the requirements for the class location in which it i s installed.

Interpretation: 1-3

Date Issued: April 19,1983

Subject: Design Safety Factors

File: 1612

Question: If underthickness is not allowed in pipe fabrication specification, may a safety factor greater than 0.72 be used in ANSI/ASME B31.4 and ANSI/ASME 831.8 construction?

Reply: There is no provision in ANSI/ASME B31.4 or ANSI/ASME B31.8 to permit a design factor greater than 0.72 to be used in the design of a liquid petroleum pipeline or natural gas pipeline.

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7009275 O022356 557


Interpretation: 1-4


Subject: Area of Reinforcement for Contoured Integrally Reinforced Fittings

File: 1681

Question: Do the rules for extruded outlets apply to contoured integrally reinforced fittings? If not, what are the correct equations indicated in ANSI/ASME B31.1, B31.2, B31.3,831.4, and B31.8 to be used in determining the limits of area reinforcement for contoured integrally reinforced branch connecting fittings (e.g., weldolet) and extruded outlets?

Reply: The contoured integrally reinforced fitting is not an extruded outlet. The equations set forth in the B31 Codes for determining the reinforcing limits of an extruded outlet do not apply in determining the reinforcing limits of a contoured integrally reinforced fitting.

The equations set forth in the Code documents for fabricated intersection area reinforcement limits are the only equations available for contoured integrally reinforced branch connecting fittings.

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Cases Code for Pressure Piping - B31.8

(The Cases are not part of ANSIIASME 831.8 or the Addenda and are included for information only.)

A T a s e ' ' is the official method of handling a reply to an Inquiry when study indicates that the Code wording needs clarification, or when the reply modifies the existing requirements of the Code, or grants permission to use new materials or alternate constructions.

It has been agreed to publish Cases issued by the B31 Committee concerning B3î.8 as part of the subscription service to 831.8. There are currently no active 831.8 Cases. However, following this t i t l e sheet i s Case 137 which is related to all 831 Codes.

The text of proposed new and revised Cases will appear in Mechunicu/ Engineering for public review. A notice will also appear in Mechunicul Engineering when new and revised Cases are approved. The Cases will then appear with the next regularly scheduled Addenda to B31.8.

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CASE 137 September 1981

This case shall expire on December 31,1986, unless previously annulled or reaffirmed.

CASES CODE FOR PRESSURE PIPING - B3 1.8

Case 137 - Piping Not Covered by Any ANSUASME 831 Code Section

InquiTy: When no Section of the ASME Code for Pressure piping, B31, specifically covers a piping system, which Section should be used for materials, design, fabrication, assembly, erection, examination, inspection, and testing of this system?

Reply: At his discretion, the user may select any Section determined to be generally

applicable. However, it is cautioned that supplementary requirements to the Section chosen may be necessary to provide for a safe piping system for the intended application. Technical limitations of the various Sections, legai requirements, and possible applicability of other codes or standards are =me of the factors to be considered by the user in determining the applicability of any Section of this Code.

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