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Chapter Three

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ASME B16.5-1996 – Pipe Flanges and Flanged Fittings

Do Not Duplicate

ASME B16.5

These course notes have been prepared by TWI, strictly for the use of attendees to this TWI API-570 Examination Preparation Course. This manual is to be used as an aid to assist those persons wishing to take the API-570 Piping Inspector Certification Examination. This manual is not all-inclusive and may not be used in place of any recognized Code or Standard. This manual may not be reproduced by any

means without the express written consent of TWI.

THE WELDING INSTITUTE

REV.002 ASME B 16.5 Copyright © TWI Ltd 2008

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SECTION 1 – SCOPE 1.1 General

ASME / ANSI B 16.5 covers:

• pressure-temperature ratings, • materials, dimensions, • tolerances, • marking, • testing, and • methods of designating openings for pipe flanges fitting NPS ½ through NPS

24.

NOTE: NPS – Nominal Pipe Size, below 6 inch = o.d. above 6 inch = i.d.

Definitions

No definitions are present in ASME / ANSI B 16.5 so the following is a non-exhaustive list of common flange and fitting terminology. Flange: A single disc or a protruding disc

extension on a body with holes to accept bolts or with holes drilled and tapped into its surface with Tap End Studs installed, with a sealing means, used to join pressure containing equipment.

Flange, ANSI: A flange specified in American National Standards Institute published standards.

Flange, API: A flange specified, now or in the past, in American Petroleum Institute published standards.

Flange, Adapter:

Any flange that will connect between two other flanges that would otherwise not connect. Usually a Double Studded Adapter (DSA), or a Single Studded Adapter (SSA).



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Flange, Blind: A flange with no centre opening, designed to close off an outlet or end connection.

Flange, End Connection:

A flange integral with a body (e.g. spacer spool, etc.) with an opposite integral connection.

Flange, Flat Face:

Most common uses are for mating with non-steel flanges on bodies of pumps etc.

Flange, Instrument:

A flange, usually made as a spacer with a ring groove on both sides to go between two other flanges, with special tapped connections through its side (O.D.), to facilitate the injection or sampling of fluid or the measurement of pressure.

Flange, Integral:

A flange made as part of a Body or attached to a body by welding. The flange Material conforms to specification requirements for integral flanges.

Flange, MSS: A flange specified in Manufacturing Standardization Society, Standard Practice SP-44. Used by manufacturers of Diverters in 30" 500 and 30" 1000 psi working pressure.

Flange, Open Face:

A flange connection with through bolt holes. An open face flange will mate with another open face flange or with a Studded Face Flange.



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Flange, RTJ:

A flange that utilizes a Ring Gasket has the designation "Ring Type Joint", abbreviated "RTJ" in flange standards other than API Spec. 6A. All API Spec. 6A flanges have "Ring Type Joint" sealing surfaces.

Flange, Raised Face:

The raised face is used in 80% of all flanges. The face height varies depending on certain ranges in pressure.

Flange Series: An out of date term, applied in

the past to API flanges now described in terms of working pressure.

Flange, Slip On:

A flange fillet welded to the pipe

Flange, Spacer:

A flange, made with a ring joint connection on both sides, to go between two other flanges to space them apart for some special purpose.

Flange, Studded Face:

A flange connection with the bolt circles drilled and tapped into its face so as to accept Tap End Studs (e.g. the connections on a Studded Cross). A studded face flange will mate only with an Open Face Flange.

Flange, Test: A flange with a tapped port in its centre or side to allow application of pressure or attachment of a gauge.



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Flange, Threaded:

A flange with an internal or external thread opposite its Ring Groove side to mate with standard threaded pipe.

Flange, Weld Neck:

A flange with a butt weld neck for welding attachment to pipe or tubing. Material may vary from that required for Integral Flanges in order to facilitate field welding.

SECTION 2 – PRESSURE-TEMPERATURE RATINGS

This section is general information on flange temperature and pressure ratings based on the type of flange, bolting and gasketing.

SECTION 3 – SIZE

3.1 Nominal Size

The size of flanges are covered by the nominal pipe size, NPS. NOTE: The new form for this designation is NPS 6, which was commonly 6” pipe.

SECTION 4 – MARKING

4.1 General

Flanges shall be marked as required in MSS SP-25. The following shall be marked on the flange:

• Manufacturer’s name or trademark • Material

cast - ASTM specification plate - ASTM specification

• Rating Class • Designation (B16 if conforms to this standard) • Temperature (none required) • Size



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• The letter R if Ring Joint Flange

SECTION 5 – MATERIALS

5.1 General

The materials for flanges and flanged fittings have been grouped, see Tables 1 and 2. NOTE: the groups are not numbered consecutively.

5.2 Bolting

This section covers general bolting, (Table 1B) high strength bolting, intermediate strength bolting, low strength bolting, bolting to gray cast iron flanges and gaskets, Table 1B.

SECTION 6 – DIMENSIONS

Dimensions for wall thickness, local areas, center-to-center and center-to-end flanges and fittings. Faces and types, lapped joints, raised face, tongue and groove, ring joint, blind flanges and flanges facing finishes are generally discussed in this section. Bolt holes, spot facing, welding end preparation reducing flanges, threads and gaskets are also highlighted.

SECTION 7 – TOLERANCES

Tolerances for center-to-center and center-to-end flanges and fittings. Faces and types, lapped joints, raised face, tongue and groove, ring joint, hub dimensions and bore of flanges are generally discussed in this section.

SECTION 8 – TEST

General test information about testing flanged fittings. Flanges are not required to be hydrostatically tested.

The rest of this document is tables and diagrams used for references and dimensions of flanges and flanged fittings.



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ASME B16.5 – PRACTICE QUESTIONS

1. ASME B 16.5 does not cover : a. Class 150 flanges b. Class 300 flanged fittings c. Butt welded pipe caps d. All of the above

2. The maximum hydrostatic test pressure permitted for a flange in a system hydrostatic test is : a. Not required b. Conducted at 1.5 x class rating @ 100 0 F c. Conducted at 25 psi above class rating d. Required only for welded flanges

3. "High strength" bolting is described as equivalent to : a. ASTM A 193 B5 b. ASTM A 193 B7 c. ASTM 320 GR 8 d. Any high carbon steel bolt

4. The pressure class ratings covered by ASME B16.5 are a. 150, 300, 400, 600, 900, 1500, 2500 b. 150, 300, 400, 450,600,900,1500 c. 125, 150, 300, 400, 600, 900, 1500, 2500 d. 150, 300, 400, 600, 700, 900, 1000, 1500

5. The standard finish for raised face flanges per ASME B16.5 is : a. 250μ to 500 μ / inch b. 125 μ to 250 μ / inch c. 260 mm to 500 mm / inch d. 250 μ / mm to 500 μ / mm

6. Socket weld and threaded flanges are not recommended for service beyond the following temperatures if thermal cycles are involved :

a. –20 – 6500F b. –30 – 6000 F c. –50 – 5000F d. –50 – 5000F

7. "Low strength " bolting is " a. ≤ 30 KSI yield strength b. ≥ 30 KSI yield strength c. ≥ 30 KSI tensile strength d. ≥ 100 KSI yield strength

8. Ring joint sidewall surfaces ( gasket groove ) must not exceed ______________roughness. a. 50 μ / in b. 63μ / in c. 100 μ/in d. 63 mm / in

9. Which of the following items must be marked on all flanges or flanged fittings?

a. Temperature b. Actual working pressure c. ASTM material specification d. Hydrotest pressure



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10. When used above ________ 0F, class 150 flanges may develop leakage unless special precautions are taken regarding loads or thermal gradients.

a. 150 b. 300 c. 600 d. 400

11. The three basic parts to a flanged joint are : a. Flanges, welds, gaskets b. Flanges, bolts, nuts c. Flanges, bolts, gaskets d. Flanges, gaskets, threads

12. Class 600 flanged joints may develop leakage, unless special considerations for thermal gradients are applied at temperatures above ________ 0F.

a. 600 b. 800 c. 950 d. 750

13. A Class 400 flanged fitting must be hydrotested at what pressure, if the 1000F rating is 800 psig? a. 1020 psig b. 1200 psig c. 1225 psig d. Not required per ASME B 16.5

14. The maximum temperature for hydrotesting a fitting is : a. 12 0F b. 1250C c. Per Construction Code requirements d. Per Owner / User system requirements

15. The minimum duration for hydrotesting on NPS 12 fitting shall be: a. 2 min b. 1 min c. 3 min d. No requirements to test fittings



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ASME B16.5 ANSWER KEY

1 C 2 B 3 B 4 A 5 B 6 C 7 A 8 B 9 C 10 D 11 C 12 D 13 B 14 A 15 C 16 17 18 19 20

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