2009 NJ BusiNess of the Year1

Becht Engineering www.Becht.comFall 2012Newsletter

By TrEvor SEipp

By Don FrikkEn

Continued on Page 5

Continued on Page 5

In 2011, Becht Engineering was approached by a major refiner on the US West Coast to assist with the evaluation of two vacuum towers. Due to a process change, corrosive products were occurring at elevations in the towers where there was

insufficient protection against corrosion. As a result, significant and extensive corrosion was measured. In many places, the wall thickness was less than the tmin established by conventional engineering assessments.

Trevor Seipp, P.Eng. from Becht Engineering’s office in Calgary, Canada took on the job of evaluating the towers’ fitness-for-service. Typical evaluations of local thin areas in pressure vessels and piping are performed frequently and easily by skilled engineers. However, this particular situation was unique in that the corrosion was extensive – the corrosion map data for each tower had over 20,000 data points, and the normal operating condition for the vessel was external pressure (vacuum).

Fitness-For-Service of a Vacuum Tower with Wall Thinning Assessment Avoids Unnecessary Downtime

In addition to the many clarifications, updated references to codes and standards, updates to basic allowable stresses, and added listed materials, there are several substantive changes to the 2012 Edition

of ASME B31.3, Process Piping. These changes are:

Category D FluiD ServiCe

The definition was revised to include piping with design minimum temperatures below -29⁰C (-20⁰F) if the cause of the lower temperature is from ambient conditions.

allowable DiSplaCemeNt StreSS raNge

The allowable displacement stress range was limited to 60,000 psi (414 MPa) in the 2012 edition. High strength steels have higher yield and tensile strengths and thus higher allowable stresses. Therefore, they also have higher calculated allowable displacement stress ranges when calculated using the old formula. However, these materials have fatigue strengths similar to the more common steels, which is why the limit was added.

Flexibility StreSS equatioN

The axial stress was added to the flexibility stress equation. While axial stress in not important in most piping systems, it can be important for piping that is jacketed or buried. The 2010 edition required that it be considered, but it was not in the equation.

welDiNg qualiFiCatioN

Restrictions to acceptance of previously qualified welding procedures were removed. Specific language about use of standard welding procedures as permitted by ASME BPV Code, Section IX was added.

Changes In the 2012 Edition of ASME B31.3

2009 NJ BusiNess of the Year2

Coopers Creek Chemical (CCC) is a specialty chemicals and coating company located in the outskirts of Philadelphia, PA. This family owned and operated business fractionates coal tar into a wide variety of coating products and a naphthalene rich

stream sold to a naphthalene marketing company for additional processing. Becht Engineering (HEA division) has been servicing CCC as it’s “go to” engineering department for many years, solving a wide variety of problems including heat transfer, instrumentation, metallurgy, vent recovery, tank certification and, most recently, conversion from 100% #2 Oil Fuel to Natural Gas for all processing and heating services.

Our role was to develop project economics, review piping bids, help with piping layout, observe construction and identify safety related issues including listing of and providing support during the completion of Management of Change requirements.

This conversion will reduce the fuel cost for their operation by more than 50% due to the very attractive pricing for natural gas. The cleaner burning fuel helps with better heat extraction from stack gases and will also improve equipment life cycles due to reduced fouling. The cost of piping will be recovered in less than six months. CCC has retained the ability to return to oil fuel in the future, in the unlikely event natural gas prices rise significantly.

Our client is very pleased with the outcome of this project and proud to be taking advantage of the surge in natural gas production that will be helping many US companies stay in business and new ones start up because of this very cost competitive fuel.

Fuel Switch Pays for Itself in Six Months

Iraq FFS

A major oil company revitalizing an Iraqi oil field called on Becht Engineering to review several hundred pressure vessels to determine their fitness for service

(FFS) per the API-579/ASME-1 process. Using ultrasonic testing (UT) and visual inspection data, Becht Engineering customized its proprietary Local Thin Area (LTA) Fitness for Service (FFS) evaluation software to create a program capable of evaluating the maximum allowable working pressure (MAWP) of these pressure vessels in an efficient manner. The software streamlines the API-579/ASME-1 calculation process, simplifies the user interface and presents the results in a user-friendly format, for evaluation by engineers and managers. Because of the extensive nature of the corrosion, large files of UT scanning data needed to be evaluated, and the software was enhanced to be able to efficiently handle this data. This highly efficient process allows rapid evaluation of vessels, most in less than one week’s time. Becht’s software modification has also included the COMPRESS vessel design software output as an input to these FFS assessments. Becht has performed Level I and Level II LTA analyses on various vessels, evaluated sections of vessels for total replacement, analyzed external damage caused by shrapnel from previous wars, and developed repair procedures within the means of the maintenance team for this remote oil field.

Arve Holt, Becht Engineering, John Kinast, plant manager, Scott Morris, VP, Al Morris, President and Mark Morris, VP.

By DavE vahlSing

By john BaSil

2009 NJ BusiNess of the Year3

MaChinEry ChaT

By STanlEy FuSSEll anD ranDy paSSMan

Continued on Page 4

Vibration Issues With a Large Catalyst Drier

Summary

At a gulf coast site, a large catalyst drier began experiencing vibrations after start up and suffered a failure. The drier internal diameter is approximately 7 feet, measures 40 feet long and is supported at each

end by 2 large trunion shafts on which are mounted 2 rollers. There is a large ring gear mounted on the outside diameter of the drum at the feed end. A variable frequency drive motor is mounted to and drives a reduction gearbox. On the output end of the gearbox is a pinion gear that meshes with the ring gear located on the drier. This arrangement provides infinite speed adjustment of the drier. Excessive vibrations had occurred shortly after commissioning and damage to the teeth on the ring gear resulted. Repairs were made and the unit started again at which point the author was contacted to perform an analysis. This was accomplished by using a 16-channel ZonicBook 618 analyzer to capture continuous data for post processing and analysis. As part of this project, impact testing was also performed on the motor / gearbox drive system of the unit. The motor / gearbox system had 2 natural frequencies identified at 1425 cpm and 1125 cpm which are within the operating speed range of the motor. For this reason, excessive overall motor vibrations of 0.3 ips to 0.7 ips were observed during the analysis period. With the gearbox pinion being overhung from the original support, this also resulted in vibration of the pinion against the ring gear. This may have contributed to the pinion failure experienced earlier. Amplification factors of 32 and 60 were calculated for the horizontal and vertical vibration responses respectively. A temporary motor support was fabricated and installed to increase the horizontal and vertical stiffness of the system, in effect raising the natural frequencies above the operating speed range of the VFD motor. Vibration amplitudes taken on the motor after installation of the support were reduced to between 0.1 ips and 0.2 ips. These values were observed during all three test conditions (ambient, hot, and hot with feed). These are very acceptable values. A permanent support was designed and installed. The unit is now operating with acceptable vibration levels. Aside from the resonant condition, the structural stiffness of the original support for the motor / gearbox system (1000 lb./mil) was not sufficient to maintain good alignment between the pinion and ring gear. All trunion bearings appeared to be in good condition with no bearing defect frequencies apparent in the spectral data.

DiSCuSSioN aND DoCumeNtatioN oF aNalySiS

Figure 1, to right, shows two plots. The top plot is a dynamic stiffness transfer function plot. The bottom plot is a spectrum of the response accelerometer located at the motor opposite drive end horizontal position. To generate this plot, the motor / drive system was impacted with a calibrated force hammer in the horizontal direction and the subsequent response measured on the drive system in the horizontal direction. In the top plot the units are in pound force per mil displacement. In general, the stiffness of any system is fairly constant until the application of

the force is placed and removed at a frequency corresponding to a natural frequency. When applied at a natural frequency, the stiffness drops dramatically, and results in a small amount of force causing a large displacement. As can be seen in the top plot, the stiffness of the motor / drive system is fairly constant at more than 1000 pounds per mill or 1,000,000 pounds per inch. This value is fairly low compared to normal design stiffness of other machinery categories. What is of major significance is the fact that a natural frequency exists in the horizontal direction at a frequency of 1425 cpm. At 1425 cpm it can be seen that a force of only 3.274 pounds results in a displacement of 1 mil. When the data was taken on November 19, 2010 the motor speed was reported at 1400 rpm. Operating at this speed, which is almost exactly at the horizontal natural frequency, resulted in overall vibration amplitudes between 0.3 ips and 0.7 ips (instantaneous values of 1.6 ips were measured).

Figure 1

Figure 2, on page 4, is a time waveform of the response accelerometer located on the motor opposite drive end horizontal location during the horizontal impact test. From the cursor positions shown in the plot, it can be seen that the response takes well over 1.5 seconds to decay. This is a result of very little damping and high amplification factors resulting from fabricated steel supports and foundations. There are 15 cycles between the cursor time positions of 0.1738 seconds and 0.8027 seconds. This calculates to a frequency of 1431 cycles per minute which is the natural frequency. From the amplitudes shown at the 2 cursor positions (0.0671 ips and .0153 ips) it was calculated that the system has a critical damping ratio of 1.57% and an amplification factor of 32.88. In other words any amount of vibratory energy input at a frequency of 1431 cpm will be amplified 32.88 times, resulting in unacceptable vibration. As an example, a new energy efficient motor manufactured to the IEEE 841 standard that had a 1x horizontal vibration of 0.04 ips on a shop test stand would have a 1x horizontal vibration of 1.32 ips in this application.

2009 NJ BusiNess of the Year4

machinery Chat - vibration issues with a large Catalyst Drier (Continued from Page 3)

Figure 2

Figure 3 below presents the same type plots as seen above for the vertical impact testing of the motor / gearbox system. In this case it is seen that a natural frequency exists at 1125 cpm in the vertical direction. This is due to a lower stiffness in the vertical direction than the horizontal direction due to the geometry of the support system. As can be seen the average stiffness is just at 1000 pounds per mil which is slightly lower that the stiffness seen for the horizontal direction in Figure 1 above. Again, this stiffness is lower than that usually seen for machinery of this type. What is of major significance is the fact that a natural frequency exists in the vertical direction at a frequency of 1125 cpm. At 1125 it can be seen that a force of only 2.592 pounds results in a displacement of 1 mil. When the data was taken on November 19, 2010 the motor speed was reported at 1400 rpm. Operating at this speed, which is very near the vertical natural frequency, resulted in overall vibration amplitudes between 0.4 ips and 0.7 ips (instantaneous values of 1.5 ips were measured).

Figure 3

Figure 4 below is a time waveform of the response accelerometer located on the motor opposite drive end vertical location during the vertical impact test. From the cursor positions shown in the plot, it can be seen that the response takes well over 1.5 seconds to decay. Again, this is a result of very little damping and high amplification factors resulting from fabricated steel supports and foundations. There are 22 cycles between the cursor time positions of 0.1730 seconds and 1.345 seconds. This calculates to a frequency of 1126 cycles per minute which is the natural frequency. From the amplitudes shown at the 2 cursor positions (0.0763 ips and .0244 ips) it was calculated that the system has a critical damping ratio of only 0.8% and an amplification factor of 60.6. In other words any amount of vibratory energy input at a frequency of 1126 cpm will be amplified 60.6 times, resulting in unacceptable vibration. As an example, a new energy efficient motor manufactured to the IEEE 841 standard that had a 1x vertical vibration of 0.04 ips on a shop test stand would have a 1x vertical vibration of 2.42 ips in this application.

Figure 4

eDitor’S CommeNt, or, a “CoNCluSioN”

to thiS artiCle:

The circumstances described in this analysis are another example (see the June, 2012 Machinery Chat Article “The Potential Pitfalls of Fabricated Machinery Foundations” of the potential vibration/stiffness issues of fabricated machinery supports. The design of fabricated machinery supports in most organizations is assigned to structural designers. These folks usually do not have a background or experience in machinery applications. It is considered an industry-best-practice when designing fabricated machinery foundations to encourage, or even insist upon, collaboration between the structural designers and machinery experts.

But should an unexpected or unexplained vibration or failure issue develop, Becht Engineering has personnel with industry leading experience and expertise to help solve the most challenging vibration issues.

2009 NJ BusiNess of the Year5

Trevor was able to quickly write a custom-made subroutine for our finite element analysis software, ABAQUS, that used the corrosion map to modify a finite element model to accurately simulate the corrosion extent with the actual remaining wall thickness. Using this tool, we were also able to simulate future uniform corrosion forecasts. Finally, we performed an elastic-plastic stress analysis that also accurately simulates buckling failures. It is vitally important to evaluate for buckling failures because that is the primary failure mechanism of vessels that operate under external pressure (vacuum).

Each tower was evaluated for fitness-for-service at the current corrosion state. Each tower was fit-for-service. Future uniform corrosion forecasts were also evaluated from the current time to the next scheduled maintenance outage. One tower was fit-for-service at the next maintenance outage. The other tower would not meet the required design margin at the next maintenance outage, but was not predicted to actually fail. However, state law and good engineering practice require compliance with the required design margin. Accordingly, a fillet-welded lap patch repair was designed. This repair was also simulated in the analysis to determine if it would be suitable; and it was.

All of this work was completed in less than 3½ weeks; on-time and under-budget. Becht Engineering’s report was presented to the State Pressure Vessel Regulator and as a result the refinery was permitted to continue operating. The scheduled maintenance outage has since occurred and there were no further incidents with the vacuum tower.

Fitness-For-Service of a vacuum tower (Continued from Page 1)

Changes to aSme b31.3 (Continued from Page 1)

preheatiNg

The 2012 edition changed “recommended” preheat tempera-tures to “required” preheat temperatures. All metals must now be preheated to 10⁰C (50⁰F) or higher before welding.

owNer’S iNSpeCtor

The qualification requirements for an Owner’s Inspector were broadened in the 2012 Edition.

mpa StreSS table

The MPa allowable stress table first appears in the print ver-sion in the 2012 edition. This table is still just for information. The psi allowable stress values are the requirement.

Changes to aSme b31.3

2009 NJ BusiNess of the Year6

beCht eNgiNeeriNg StaFF iS aCtive iN NatioNal CoDeS aND StaNDarDS CommitteeS

aSme CommitteeSBoard of Governors - Current & Former MembersBoard on New Development - Current ChairBoard on Hearings and Appeals - Former ChairBoard on Nuclear Codes and Standards

- Current Member, Former ChairBoard on Pressure Technology Codes and Standards

- Former Chair, VP & MembersBoard on International Standards (Inactive Committee)

- Former MemberBoard on Council Operations - Former ChairsCouncil on Standards and Certification

- Current Member, Former Chairs & Sr. VP’s

aSme poSt CoNStruCtioN StaNDarDSPost Construction Standards Committee

- Former Chairs & Vice-ChairsPost Construction Executive Committee

- Current Members, Former Chairs & Vice-ChairsSubcommittee on Repair and Testing - Founding Chair,

Current Member, Former Chair & MembersSubcommittee on Inspection Planning

- Current MemberSubcommittee on Flange Joint Assembly

- Current ChairSubcommittee on Flaw Evaluation - Former Member

aSme boiler aND preSSure veSSel CoDe CommitteeS

Committee on Pressure Vessels (BPV VIII) - Current Chair & Members, Former Members

Subcommittee VIII, Pressure Vessels (Inactive Committee) - Former Vice-Chair & Members

Committee on Transport Tanks - Former MemberCommittee on Construction of Nuclear Facility

Components - BPV III - Current Vice-ChairDesign and Analysis Committee (Inactive Committee)

- Former Chairs & MembersSubgroup on Design Analysis (BPV III & VIII)

- Former Chairs & MembersExecutive Committee on Strategy and Project

Management (BPV III) - Current ChairProject Team on Hydrogen Tanks - Current MemberSpecial Committee on Interpretations (BPV III)

- Current ChairSpecial Interpretations Committee (SC-VIII)

- Current MemberSpecial Working Group on High Density Polyethylene

Piping (SC III) - Current MemberSpecial Working Group on High Pressure Vessels,

Section VIII, Div 3 (Inactive Committee) - Former Chair

Standards Committee on Qualification of Mechanical Equipment - Current Member

Subcommittee on Accreditation - Former Member-Alternate

Subcommittee on Design - (Inactive Committee) - Former Members

Subgroup on General Requirements (BPV III) - Current & Former Members

Subgroup on High Pressure Vessels (Section VIII, Div 3) - Current Member, Former Chair

Subgroup on Design (BPV VIII) - Current Member, Former Chair & Members

Subgroup on Design SC-VIII (Inactive Committee) - Former Chair & Members

Subgroup on on Design/Analysis (SC-D) (Inactive Committee) - Former Chair & Members

Subgroup on General Requirements (BPV VIII) - Current Member, Former Chair

Subgroup on Heat Transfer Equipment (BPV VIII) - Current Member, Former Chair

Subgroup on Toughness (BPV II & VIII) - Current Member

Subgroup on Component Design - Current MemberSubgroup on Elevated Temperature Design

- Current Member, Former Chair

Task Group on Impulsively Loaded Vessels (SC VIII) - Current Members

Technical Oversight Committee (former Main Committee) - Current & Former Members

Working Group on Piping (BPV III) - Current Members, Former Chairs & Vice-Chair

Working Group on Piping (SG-D) (BPV III) - Current Member

Operation and Maintenance of Nuclear Power Plants – Piping Group - Current Member

Task Group on Buried Pipe - Current MemberWorking Group on Supports (BPV III) - Former MemberWorking Group on Design-By-Analysis (BPV VIII)

- Current MemberSubgroup on External Pressure (BPV II)

- Current Vice-Chair

aSme pipiNg aND CompoNeNt CoDeS aND StaNDarDSB31, Code for Pressure Piping, Executive Committee

- Current & Former MembersB31, Code for Pressure Piping, Mechanical Design

Committee - Current Vice-Chair & Member, Former Vice-Chair

B31, Code for Pressure Piping, Standards Committee - Current Members, Former Chair

B31.3, Process Piping Section Committee - Current Members, Former Chairs

B31.12 Hydrogen Piping and Pipelines Section Committee - Current Members

B31.3 Subgroup on High Pressure Piping - Former ChairB31.3 Subgroup on Design - Current & Former MembersB16 Standards Committee for National & International

Standardization of Valves, Flanges, Fittings,Gaskets - Current Member

B16 Subcommittee on Steel Flanges and Flanged Fittings - Current Member, Former Chair

B16 Subcommittees on fittings, gaskets, copper components and valves - Current Member

aSme/apiASME/API Joint Fitness-for-Service Committee (API

579/ASME FFS-1) - Current Member, Former Vice-Chairs & Members

aSCeWorking Group on Revision of ASCE Standard 4 Seismic

Analysis of Safety-Related Nuclear Structures - Voting Member

ASCE Dynamic Analysis of Nuclear Structures (DANS) Committee - Current Member

apiCommittee on Risk Based Inspection - Former MemberCommittee on Materials and Corrosion

- Former MemberCommittee on Refining Equipment - Former MemberSubcommittee on Heat Transfer Equipment

- Former ChairSubcommittee on Above Ground Storage Tanks

- Former MemberSubcommittee on Piping - Former Vice-ChairTask Group on Materials for Heavy Wall Vessels

- Former ChairTask Group on API 580 - Former MemberTask Group (934F) for Development of a Guidance

Document for Establishing Minimum Pressurization Temperatures for Heavy Wall Reactors in Hydrogen Service - Current Member

Task Group (934G) for Coking Drums in Delayed Coking Units - Current Member

Task Group (941) for High Temperature Hydrogen Attack - Current Member

Task Group on Shell & Tube Heat Exchangers - Former Member

Task Group on Air Cooled Heat Exchangers - Former Member

API 582 – Welding Guidelines for the Chemical, Oil and Gas Industries - Former Chair

aDDitioNal Committee iNvolvemeNtMTI - Board of Directors - Current MemberMTI – Knowledge Management Project Development

Committee - Current ChairAWS A5 (Filler Metals) Committee - Source for ASME

IIC - Current MemberASTM F-17, Plastic Piping Systems Main Committee

- Current MemberASTM Standards and Certification Board of Directors

- Current Member, Former ChairASTM Committees CO3, C-16, and D-20.23

- Current MemberISA – The International Society for Measurement &

Control, member of SP 93, Sealing Technologies Committee - Former Member

Materials Technology Institute’s Technical Advisory Council Committee - Current Member

Materials Technology Institute, Evaluation of Gaskets Committee - Current Member

US TAG for ISO/TC 153/SC 1 – Valve Design, Manufacturing, Marking and Testing - Current Member

US TAG for ISO/TC 5/SC 10 – Metallic Flanges and Their Joints - Current Member

US TAG for ISO TC 197 – Hydrogen Technologies - Current Member

US TAG for ISO TC 11 - Boilers and Pressure Vessels - Current Member

Joint ASME – IEEE Seismic Qualification Committee - Former Chair

ASME – ASCE Joint Task Group on Buried Piping - Founding & Current Chair

Process/Industry Practices (PIP): Coatings and Insulation - Former Function Team Leader

Process Industry Practices (PIP): Piping - Former Member

Society for Protective Coatings (SSPC): Standards Review Committee - Former Member

US DOE Hydrogen Safety Panel - Current MemberThe Materials Properties Council - Former MemberSection III, SG on General Requirements - Current

MemberSection III, SWG on Polyethylene Pipe (Inactive

Committee) - Former MemberSection III, Working Group on Piping Design (Inactive

Committee) - Former MemberPVRC Committee on Continuing Operation of

Equipment - Former ChairASME Hydrogen Steering Committee (Inactive

Committee) - Former ChairASME High Pressure Systems Committee

- Former Vice-Chair & MemberASME Task Group on Risk Analysis for the Critical

Assets Protection Initiative - Former Chair & MemberASME BPTCS Ad Hoc Task Group on Incorporation of

Risk Based Principles into Pressure Technology Codes and Standards - Former Chair & Member

PVP Design and Analysis Committee - Current ChairPVP Executive Committee - Current MemberWorking Group Duties and Responsibilities (SGGR-

BPVIII) - Current MemberQAI-1 Qualification for Authorized Inspection

- Former ChairSubcommittee on Accreditation of Authorized

Inspection Agencies - Current Member-AlternateNational Commission for the Certification of Crane

Operators (NCCCO) - Vice President, Board of Directors