Volume Number 27 SummerFall 2009

The Changing Role of Renewable Generation

P6-7

Ultrasonic Phased Array Examination of Butt-Fusion Joints in High-Density Polyethylene

P10

Integrity Management Support for Gas Distribution Operators

P12

Training on High Energy Piping Inspections and Non Destructive Evaluation Techniques NEWS amp VIEWS P15

Allen Porter Marshal Clark Dan Peters Sean Hastings aporterstructintcom mclarkstructintcom dpetersstructintcom shastingsstructintcom

Complete Integration of Steam Chest Structural Analyses

Turbine steam chests are fundamental components controlling the flow of steam from a steam source to a turbine Steam chests over time are susceptible to high temperature creep damage thermal transient loads as well as normal operational wear Structural Integrity Associates (SI) offers a completely integrated approach to evaluate steam chests and like components including Solid Model Generation finite element analysis (FEA) lifing nondestructive examination (NDE) inspection long term instrumentation and monitoring and expert metallurgical oversight

Model Generation The basis of the work starts with the creation of a parametric Solid Model using Solid Worksreg a three-dimensional parametric solid modeling package as displayed in Figure 1 The design intent of the Solid Model is to generate a partitioned single part made up of many bodies This allows for discrete surface entities to aid in applying relevant loads as well as facilitating appropriate mesh controls The complex geometry created may be subsequently used in NDE technique development and finite element (FE) stress analysis The results of this analysis can be used as input for stress linearization fracture mechanics creep damage life fraction and determination of potential failure modes A basic stress analysis can also pinpoint areas of concern in a given steam chest that could result in failure on

Figure-1 a long term basis The identification of these areas can help in the (Parametric Solid Model Generated using Solid Works) minimization of risk in operation of the steam chest and identify critical

areas for either periodic NDE inspection or long term monitoring Continued on page 4

rsquo

-

-

-

PreSIdentrsquoS Corner

Laney Bisbee lbisbeestructintcom

Last month I visited India where we conducted a workshop on the asset management of critical high energy piping for fossil power plants (for more on this see Training on High Energy Piping

Inspections and Non-Destructive Evaluation Techniques for Coal Fired Power Plants on page 15) What I saw and heard from Indian utilities was markedly different from the talk in the current US generation environment In India there is a critical need for additional capacity with a corresponding aggressive plan to build new conventional fossil and nuclear plants That is certainly not the focus in the US

Over the past few years the US power industry primarily defined as conventional fossil and nuclear plants has been in a bit of a sideways slide Just as we thought a direction was clear and new construction was about to begin we experienced a number of social economic and political changes that have altered industry s direction The last twelve months are a perfect example as plans for building new fossil and nuclear plants continue to slide Specifically

Global financial stability and credit market concerns have severely impacted the global economy reducing demand for additional capacity in the US

Fossil fuels have increasingly come under fire for concerns of both environmental impact and price volatility

The nuclear construction renaissance was on then off then on then off ndash fluctuating with the credit markets and energy policy

A new administration was elected with the corresponding uncertainty on changes to energy policy and impacts on the energy industry from the economic stimulus plan

Energy-related elements of the stimulus plan focus on the development of a smart grid renew able energy and efficiency programs with minimal funding for new or existing fossil and nuclear generation

Policy uncertainties remain as CO2 cap-and-trade national renewable portfolio standards and other elements of national energy policy continue to be debated in Washington

Strong support for renewables particularly wind and solar although there are significant chal lenges on plant siting transmission and technology

Given these factors it is not surprising that many new fossil and nuclear projects in the US have been postponed some temporarily and others permanently That certainly puts a damper on the excitement in the industry with limited new growth and cutting edge technology

Fortunately therersquos still an air of excitement at SI driven by the continued growth of our core markets

Maintaining and expanding the capabilities of the current fleet (such as 60 and 80-year licens ing for the current nuclear fleet)

The design of new generating plans (like new advanced nuclear units and solar boilers) The application of new technology to solving age-old issues (applying G-scan technology to

buried piping) Asset management of new generating sources (providing much needed engineering support for

the rapidly expanding wind generation fleet)

Regardless of which direction the energy industry takes in the future I look forward to SI helping all of our clients navigate their way through it all for years to come

the Charlotte office Has

Moved

As of June 15 2009 the Charlotte staff has a new home We took advantage of an opportunity to add 12000 sq ft of space to our growing business by moving directly across the street This additional footage increases space for our engineering and technical departments lab and warehouse

The move went off without a hitch due to the great efforts of the Charlotte Facilities Team the Management Team and many others

Stop in for a tour of our new office located at

11515 Vanstory Drive Suite 125 Huntersville NC 28078

Phone 704-597-5554 Fax 704-597-0335

Vol No 27 2 SummerFall 2009

ASME 125th Anniversary

Top row left to right Bob McGill Timothy Griesbach Middle row left to right Michael Lashley Tim Gilman John Arnold Clark McDonald Dick Smith Bill Weitze Scott Chesworth Karen Fujikawa Tony Giannuzzi Dan Sommerville Ned Finney Randy McDonald Bottom row left to right Danen

Heath Darryl Rosario Paul Hirschberg Gary Stevens Rick Dixon Dan Peters Marcos Herrera Hal Gustin Angah Miessi

Daniel Peters dpetersstructintcom

Structural Integrity Associates would like to take this opportunity to congratulate ASME on their 125th anniversary celebration of Codes and Standards SI has been an avid supporter of ASME Codes and Standards for many years

ASME published its first Code in 1884 with the publication of ldquoCode for the Conduct of Trials of Steam Boilersrdquo ASME Codes and Standards are developed on a consensus basis and maintained by 700 technical and supervisory committees with over 4000 volunteers and staff members

Rick Dixon Named as ASMeFellow

SI would like to announce the promotion of Mr Rick Dixon to the grade of Fellow by ASME This promotion recognizes Rickrsquos outstanding achievement in the profession of mechanical engineering by his peers Rick was recognized for his leadership in the engineering profession his contributions to the Society dedicated efforts both from a research standpoint and in the Codification of that research

Rick has authored or co-authored several papers in the area of fracture mechanics and fatigue Rick was lead author on work relative to the use of elastic-

Vol No 27

SI is proud to be a part of that effort and participates in many key areas of the Boiler and Pressure Vessel Code Nuclear Codes and Standards the Power Piping Code and the Post Construction Codes SI has contributed to many key areas affecting the energy industry including technical support on Creep-Strength Enhanced Ferritic Steels Alloy 600 Buried Piping amp Piping Design Nuclear Plant Aging Post Construction Inspection Planning Post Construction Repair and Testing Vessel Fabrication and Examination Boiler Fabrication and Inspection Design Welding Practices High Pressure Vessels Ultrasonics and Non-Destructive Examinations just to name a few SI has also taken a leadership position by both chairing Subcommittees and by serving on the Boiler and Pressure Vessel Standards Committee on Power Boilers (Section I) Design of Nuclear Power Plant Components (Section III) Non-Destructive Examination (Section V) Boiler

plastic finite element analysis in the design of various aspects of high pressure vessels This includes the analysis of flat heads blind end closures and collapse of both closed-end and open-end cylinders Rick was lead author for an extensive project for the review and development of accurate stress concentration factors for cross-bores in thick walled cylinders and blocks This was an extensive project that encompassed approximately three yearsrsquo worth of work The project was a joint venture between researchers at three different companies on two continents

Rick was also cited for his leadership abilities while at his previous employer E I Dupont Company His talents in engineering were well known and sought out while at Dupont He consistently demonstrated his leadership abilities by mentoring new engineers by sharing his knowledge and experience to accelerate the growth of his co-workers both there and here at SI

Rickrsquos contributions to ASME are numerous to date He has worked diligently as an Associate Editor of the Journal on Pressure Technology for four years in the High Pressure Technology area Rick was nominated for this position by the High Pressure Technology Committee of the ASME Pressure Vessel and Piping Division based on the excellent work he has done as Technical Paper Representative for that committee in both 2002 and 2007 Rick is presently serving as the Vice-Chairman of the High Pressure Technology Committee of PVP He has previously held the position of Secretary from 2004-2007

and Pressure Vessels Standards Committee on Pressure Vessels (Section VIII) Subgroup High Pressure Vessels (Section VIII Div 3) and Nuclear In-Service Inspection (Section XI) Standards Committees

SI looks forward to working with ASME for the next 125 years SI would also like to acknowledge the efforts of its staff that contribute to these activities Many long hours are put in on a voluntary basis to contribute to the writing of these Codes SI has over 20 individuals that participate in these activities on a quarterly basis

So the next time you are at an ASME Code meeting or if you simply have a question regarding the ASME Codes and Standards feel free to say hello to one of these SI employees

Rick has been an actively contributing member of the Sub-Group on High Pressure Vessels of the ASME Boiler and Pressure Vessel Code since 1998 His work in the area of limit analysis for high pressure vessels and equipment is considered a seminal contribution and has laid the foundation for many of the rules in ASME Section VIII Division 3 of the Boiler and Pressure Vessel Code Rickrsquos work on propagation patterns of cracks in 1999 led to significant recommendations to the philosophy used in the fracture mechanics assessment required by Section VIII Division 3 that were subsequently adopted The investigation of stress concentration factors for cross-bores led to the publication of Appendix J in ASME Section VIII Division 3 This was considered a significant advancement to the Code The work on elastic-plastic collapse pressure of open-end cylinders is presently being used as justification for lowering the design margin in Section VIII Division 3 This is a crucial step to keep ASME as the leading Code in high pressure design while still maintaining an unparalleled level of design integrity

Rick joined SI in 2008 and presently works in the Nuclear Plant Services Group in Charlotte NC performing many types of Finite Element Analyses including weld overlay processes for determination of welding residual stresses

SummerFall 2009 3

Complete Integration

of Steam Chest Structural Analyses

Continued from page 1

LoadsConstraints In order to adequately

understand the behavior of complex assemblies a complete understanding

of the loads and supports on the steam chest is

required Once the model geometry is generated

the internal and external loads are applied to the FE model using ANSYS

Workbench Workbench is the most modern of

ANSYSrsquos preprocessors for the generation of parametric

Finite Element models The mesh and beam elements are displayed in Figure-2

Two-dimensional beam elements were utilized

to reduce the overall complexity of the FEA in the particular case considered

here

The loads are determined from a complete evaluation

of the particular steam chest These loads include

pressure thermal loads including any possible

thermal transients external loads from a separate

piping stress analysis and any supports for a given

steam chest Examples of some pressure loads are

displayed in Figure-3 the red surfaces are ones with

loads applied

Figure-2 (Beam element and Mesh Plot)

Figure-3 (Internal Pressure Loads Highlight in Red)

Results The results of the FEA can be displayed and output in a number of different ways A first look at the results includes a review of the equivalent stresses as displayed in Figure-4 This type of output can be extremely beneficial in understanding potential issues within the valve chest This type of plot can identify stress risers where potential cracking or creep may occur areas of the valve which may be experiencing localized yielding or the global displacement of the valve which could lead to distortion causing operational issues with the valve operatorsFigure-4 (FEA model displaying stresses)

Vol No 27 4 SummerFall 2009

Fitness for Service Assessments

As discussed previously one of the critical issues with any thick section

component in high temperature service is the potential for creep and thermal

fatigue cracking to occur The FE analysis not only provides insight for

likely places for this cracking to occur but the stresses calculated may also be

used in the analysis of the crack growth rates The stresses determined are the

driving forces in the growth of the cracks

Some of the most common issues in the evaluation of cracking in the valves are Determination of the size of a

critical crack in the valve Determination of the method

of failure of a crack (catashystrophic failure or leak before burst)

Evaluation of the length of the remaining life of the valve

SI presently evaluates the failure mode of components experiencing thermal

fatigue using the most advanced methods available State-of-the-art

methods in fracture mechanics such as the use of a Failure Assessment Diagram

(FAD) and creep ndash fatigue interaction using software such as SI developed

EPRI Creep-Fatigue ProTM (CFPRO) are often employed (see Figure 5 and 6) These methods include the use of

probabilistic methods for the calculation of final crack sizes and remaining life

These methods are all used to complete a Fitness for Service assessment of any

component in accordance with the most modern standard API 579-1 ASME

FFS-1 Fitness for Service Standard

Figure-7 High Temperature Instrumentation

Vol No 27

Figure-5 Creep-Fatigue ProTM (CFPRO) Crack Growth Rate Example

Figure-6 Creep-Fatigue ProTM (CFPRO) Operational Data Input Example

Instrumentation SI also has the capability of providing instrumentation solutions for the longshyterm monitoring of steam chests in high temperature service up to 1150degF with the use of thermocouples and capacitive strain gages (see Figure 7) These gages have been used in applications around the world to track the progression of creep damage in long-term monitoring applications (see Figure 8)

Conclusion SI brings the latest analysis techniques for the most accurate assessment of the most complex of components The use of complex three-dimensional modeling when coupled with state-of-the-art analysis techniques metallurgical evaluation instrumentation and long term monitoring and the most advanced and modern ultrasonic tools allows SI to be a leader in the area of fitness for service assessment and root cause evaluation of some of the most challenging problems in any power Figure-8 Micrographs of typical Creepplant components Damage

SummerFall 2009 5

ndash ndash

-

Brandon T Lindley blindleystructintcom

Although not widely advertised Structural Integrity has served the renewable market wind solar geothermal hydro and biomass power plants for years That shouldnrsquot come as any surprise though (even though clients are always saying ldquoI didnrsquot know SI did thatrdquo) as many of our skills and capabilities serving our core nuclear fossil and pipeline markets are just as applicable to the issues facing owners and operators of renewable plants

6 SummerFall 2009

With recent political and social trends itrsquos not a stretch to assume that renewable will become a greater percentage of our business as the capacity of renewable continues to grow in the United States and abroad The most significant driver of this growth is the recent administration change in Washington Although the government has been supportive of renewable energy in past years largely driven by a greater interest by the public in ldquogreenerrdquo living a step change is taking place under the current administration This is most evident by the recent passage of HR-2454 (the American Clean Energy and Security Act of 2009 also referred to as Waxman-Markey) by the US House of Representatives this year Two key elements of this bill favoring renewable energy include

The Cap and Trade provision which not only requires certain industries to pay for CO2 emissions but also includes targeted CO2 emissions reductions from 2005 levels of 3 by 2012 17 by 2020 and 80 by 2050 This

component of the bill will encourage renewable development not only by mandating emissions reductions but increasing the costs of competing fossil generation

A renewable portfolio standard targeting 20 of generation to be renewable by 2020 (although a portion of that goal can be met through efficiency gains) This provision will specifically encourage utilities to generate or purchase renewable power regardless of whether that electricity is cost competitive

In addition to the private investment in renewable generation in recent years government backed funding is also driving the push for renewables Under the Energy Policy Act of 2005 $185 billion in loan guarantees for renewable energy were made available although no guarantees were actually issued until March of this year Additional guarantees are also available from the American Recovery and Reinvestment Act (more commonly known as the stimulus bill)

Vol No 27

Fitness for Service Assessments

As discussed previously one of the critical issues with any thick section

component in high temperature service is the potential for creep and thermal

fatigue cracking to occur The FE analysis not only provides insight for

likely places for this cracking to occur but the stresses calculated may also be

used in the analysis of the crack growth rates The stresses determined are the

driving forces in the growth of the cracks

Some of the most common issues in the evaluation of cracking in the valves are Determination of the size of a

critical crack in the valve Determination of the method

of failure of a crack (catashystrophic failure or leak before burst)

Evaluation of the length of the remaining life of the valve

SI presently evaluates the failure mode of components experiencing thermal

fatigue using the most advanced methods available State-of-the-art

methods in fracture mechanics such as the use of a Failure Assessment Diagram

(FAD) and creep ndash fatigue interaction using software such as SI developed

EPRI Creep-Fatigue ProTM (CFPRO) are often employed (see Figure 5 and 6) These methods include the use of

probabilistic methods for the calculation of final crack sizes and remaining life

These methods are all used to complete a Fitness for Service assessment of any

component in accordance with the most modern standard API 579-1 ASME

FFS-1 Fitness for Service Standard

Figure-7 High Temperature Instrumentation

Vol No 27

Figure-5 Creep-Fatigue ProTM (CFPRO) Crack Growth Rate Example

Figure-6 Creep-Fatigue ProTM (CFPRO) Operational Data Input Example

Instrumentation SI also has the capability of providing instrumentation solutions for the longshyterm monitoring of steam chests in high temperature service up to 1150degF with the use of thermocouples and capacitive strain gages (see Figure 7) These gages have been used in applications around the world to track the progression of creep damage in long-term monitoring applications (see Figure 8)

Conclusion SI brings the latest analysis techniques for the most accurate assessment of the most complex of components The use of complex three-dimensional modeling when coupled with state-of-the-art analysis techniques metallurgical evaluation instrumentation and long term monitoring and the most advanced and modern ultrasonic tools allows SI to be a leader in the area of fitness for service assessment and root cause evaluation of some of the most challenging problems in any power Figure-8 Micrographs of typical Creepplant components Damage

SummerFall 2009 5

ndash ndash

-

Brandon T Lindley blindleystructintcom

Although not widely advertised Structural Integrity has served the renewable market wind solar geothermal hydro and biomass power plants for years That shouldnrsquot come as any surprise though (even though clients are always saying ldquoI didnrsquot know SI did thatrdquo) as many of our skills and capabilities serving our core nuclear fossil and pipeline markets are just as applicable to the issues facing owners and operators of renewable plants

6 SummerFall 2009

With recent political and social trends itrsquos not a stretch to assume that renewable will become a greater percentage of our business as the capacity of renewable continues to grow in the United States and abroad The most significant driver of this growth is the recent administration change in Washington Although the government has been supportive of renewable energy in past years largely driven by a greater interest by the public in ldquogreenerrdquo living a step change is taking place under the current administration This is most evident by the recent passage of HR-2454 (the American Clean Energy and Security Act of 2009 also referred to as Waxman-Markey) by the US House of Representatives this year Two key elements of this bill favoring renewable energy include

The Cap and Trade provision which not only requires certain industries to pay for CO2 emissions but also includes targeted CO2 emissions reductions from 2005 levels of 3 by 2012 17 by 2020 and 80 by 2050 This

component of the bill will encourage renewable development not only by mandating emissions reductions but increasing the costs of competing fossil generation

A renewable portfolio standard targeting 20 of generation to be renewable by 2020 (although a portion of that goal can be met through efficiency gains) This provision will specifically encourage utilities to generate or purchase renewable power regardless of whether that electricity is cost competitive

In addition to the private investment in renewable generation in recent years government backed funding is also driving the push for renewables Under the Energy Policy Act of 2005 $185 billion in loan guarantees for renewable energy were made available although no guarantees were actually issued until March of this year Additional guarantees are also available from the American Recovery and Reinvestment Act (more commonly known as the stimulus bill)

Vol No 27

ndash ndash

-

Brandon T Lindley blindleystructintcom

Although not widely advertised Structural Integrity has served the renewable market wind solar geothermal hydro and biomass power plants for years That shouldnrsquot come as any surprise though (even though clients are always saying ldquoI didnrsquot know SI did thatrdquo) as many of our skills and capabilities serving our core nuclear fossil and pipeline markets are just as applicable to the issues facing owners and operators of renewable plants

6 SummerFall 2009

With recent political and social trends itrsquos not a stretch to assume that renewable will become a greater percentage of our business as the capacity of renewable continues to grow in the United States and abroad The most significant driver of this growth is the recent administration change in Washington Although the government has been supportive of renewable energy in past years largely driven by a greater interest by the public in ldquogreenerrdquo living a step change is taking place under the current administration This is most evident by the recent passage of HR-2454 (the American Clean Energy and Security Act of 2009 also referred to as Waxman-Markey) by the US House of Representatives this year Two key elements of this bill favoring renewable energy include

The Cap and Trade provision which not only requires certain industries to pay for CO2 emissions but also includes targeted CO2 emissions reductions from 2005 levels of 3 by 2012 17 by 2020 and 80 by 2050 This

component of the bill will encourage renewable development not only by mandating emissions reductions but increasing the costs of competing fossil generation

A renewable portfolio standard targeting 20 of generation to be renewable by 2020 (although a portion of that goal can be met through efficiency gains) This provision will specifically encourage utilities to generate or purchase renewable power regardless of whether that electricity is cost competitive

In addition to the private investment in renewable generation in recent years government backed funding is also driving the push for renewables Under the Energy Policy Act of 2005 $185 billion in loan guarantees for renewable energy were made available although no guarantees were actually issued until March of this year Additional guarantees are also available from the American Recovery and Reinvestment Act (more commonly known as the stimulus bill)

Vol No 27

ndash

rsquo

Clearly there are incentives for additional renewable generation growth in the future but it will not be smooth sailing The Senate has yet to pass HR-2454 or a comparable bill of their own and with each passing day opposition to the bill as written continues to grow Funding has also not been as forthcoming as might be expected due to slow government funding and risk-averse private capital (partially driven by the uncertain impact of the cap-and-trade provision on future electricity pricing)

Of course there are other issues as well which may reign in the growth of renewable generation in the US The three most prominent issues are plant siting transmission and the state of technology

Like most power plants obtaining approval for siting can be just as challenging for renewable power plants With locations already limited to those with the renewable resource whether it be wind sun a geothermal resource or water state and federal government agencies have further restricted access to suitable lands One such example is the pressure by Senator Feinstein to prevent the development of renewable energy on 500000 acres of the Mojave Desert prime area for solar generation Of course the opposition from local residents and organizations is yet another hurdle

And once a plant is sited there is no guarantee that transmission lines will be available Most renewable projects are expected to be developed in remote sparsely populated areas with limited or no easy access to transmission Such development will require the further cost of new transmission lines not to mention the challenges of permitting as states and the federal government wrangle over authority to permit such lines

To be more efficient and cost effective many new renewable technologies are under

development from new solar gathering plants to cutting edge wave technology As with any new technology these plants as well as incrementally improved wind turbines are likely to suffer growing pains as they refine design manufacturing and installation Any significant issues could seriously derail the deployment of such technology inhibiting future investment and growth of renewable generation

Despite these obstacles it s clear that renewable generation capacity will continue to grow in the US The primary questions are how quickly and at what rate it will do so Although it does not appear that renewable generation will displace existing nuclear and fossil generation to a notable extent in the near future Structural Integrity will keep a close eye on developments and align our capabilities accordingly so we can assist our clients old and new with their issues and challenges in the future

Examples of our previous work in this market include Assessing the integrity of a wind turbine

tower after it was struck by a failed blade and numerous failure analyses of bolting blades gear boxes and towers

G-scan long range guided wave and B-scan UT inspection of geothermal plant piping and production well piping exposed to high temperature hyper-saline brine

Working with an emerging technology company on the design and analysis of a solar powered boiler

Assessing aging steel hydro penstocks to evaluate degradation and analyze susceptibility to failure

WALL RestoRatioN

CASe n-661 USInG Code

Bob McGill rmcgillstructintcom

During a recent routine inspection of A-106 Grade B piping at a Boiling Water Reactor (BWR) localized thinning below minimum design requirements was discovered The affected Class 3 18-inch XS pipe provides raw service water to the residual heat removal (RHR) system of the plant An immediate repair or replace decision was needed to address the degraded condition After careful consideration of available options a permanent weld build-up wall repair employing Code Case N-661 (ldquoAlternative Requirements for Wall Thickness Restoration of Classes 2 and 3 Carbon Steel Piping for Raw Water Servicerdquo) was selected Code Case N-661 is conditionally accepted by the NRC in Regulatory Guide 1147 The wall thickness is restored by weld-deposited carbon or low-alloy steel reinforcement on the external surface of the piping using the prescribed design criteria of N-661 For this repair E-7018 filler metal was used for the overlay with a uniform thickness equal to the nominal pipe wall Surface preparation and volumetric examination was completed to verify the repair met N-661 design requirements

SI assisted utility decision makers with their choice on the repair approach completed the engineering analysis for the wall restoration design and provided a drawing of the overlay for implementation

Vol No 27

The N-661 repair resulted in significant plant savings as compared to pipe replacement

Contact Bob McGill at rmcgillstructintcom for additional information

SummerFall 2009 7

HIGH eneRGy PIPInGamp CoMPonent ASSeSSMent PRotoCoLSASSeSSMent PRotoCoLS

Fred DeGrooth fdegroothstructintcom

Based on our industry experience of evaluating high energy piping and boiler components over the past 25 years Structural Integrity (SI) has developed rigorous protocols to help utilities address the safety and reliability concerns related to high energy component assessment This protocol differs from what traditional NDE vendors provide to the power generation industry The SI protocol is based on the engineering and metallurgy expertise of our staff Working with our metallurgists our NDE engineers developed specialized ultrasonic techniques capable of detecting material damage at its earliest stages From that other engineers in our staff utilize computer codes to calculate component life based on the test data collected

For example for the evaluation of longitudinal seam welds conventional ultrasonic techniques can theoretically detect damage after 85 of the component life has been expended The SI annular phased array UT technique can detect aligned creep cavities which occur at approximately 70 life fraction The additional sensitivity that SIrsquos protocol provides can potentially be used to extend re-inspection intervals For example a unit with 200000 hours of service can have a threefold increase in the recommended re-inspection intervals - from 3 years to 9 years The inspection techniques and technologies Structural Integrity has developed therefore can save the utility tens of thousands of dollars while giving the utility the confidence that only SI can provide Alternatively the utility industry has seen where less sensitive inspections ( ie only performing magnetic testing (MT) and time of flight defraction (TOFD) on seam welds) have not detected damage which resulted in catastrophic failures less than 2 years after these inspections were complete

8 SummerFall 2009

In addition to a specialized protocol to address the concerns associated with seam welds SI has also developed a protocol for piping and header girth welds This was generated in response to the recent increase in subsurface ldquoType IVrdquo girth weld failures that may not exhibit damage on the OD surface A summary of our protocols are listed below

Longitudinal Seam Welds

1 Visual Examination 2 Wet fluorescent magnetic particle

examinations 3 Time of Flight Diffraction (TOFD) UT

with multiple probe spacings to provide adequate coverage for the complete weld volume including the ldquoMohaverdquo and ldquoMonroerdquo initiation sites to detect fabrication and macro-level damage (micro-fissuring and worse)

4 Annular Phased Array (APA) UT using an X-Y raster scanner to interrogate specific locations of the longitudinal seam weld to detect early stage creep damage (aligned creep cavities)

Piping Girth Welds

1 Visual Examination 2 Wet fluorescent magnetic particle

examinations 3 Linear Phased Array (LPA) UT with

appropriate focal laws designed to provide adequate coverage for the complete weld volume to detect fabrication and macro-level damage (micro-fissuring and worse)

4 Annular Phased Array (APA) UT using a line encoder to interrogate four quadrants of the girth welds to detect early stage creep damage (aligned creep cavities)

5 In-situ metallography through the removal of surface plastic replication samples from two clock positions of the weld sampling both the upstream and downstream heat affected zones

SI has developed these protocols so clients can better understand the advantages of utilizing our services Technical specifications will be developed from these protocols so our clients can utilize them in Request for Proposal Packages The education of our customers in technical matters relating to our product and service offerings has always been a priority at SI For further information on SIrsquos technical protocols please contact Fred DeGrooth in the Stonington CT office at fdegroothstructintcom

Vol No 27

HIGH eneRGy PIPInGamp CoMPonentASSeSSMent PRotoCoLS ASSeSSMent PRotoCoLS

Update

by Bud Auvil CANDU Reactor lsquoFeeder Pipersquo Repairs bauvilstructintcom In another first-of-a-kind endeavor the W(SI)2 team is developing a weld overlay repair process for a CANDU

reactor operator The CANDU components involved are lsquofeeder pipesrsquo(ie fuel channel inlet and outlet piping) that have been thinned due to Flow Accelerated Corrosion (FAC) In limiting cases only frac34rdquo of field clearance

may be allowed for weld overlay repairs Phase 1 of this project addresses weld process development and demonstration material testing (hardness hydrogen concentration and metallography) NDE (UT) ASME Section III stress analysis residual stress analysis and testing conceptual repair welding and NDE tooling design and regulatory approval support (The proof of concept phase of this project was completed in 2005 by the W(SI)2 team) The second phase of the project slated for award and start later in 2009 will address additional engineering and licensing scope prototype tooling production tooling field repair (including NDE) procedures and ultimately repair commissioning at the face of the CANDU reactor Weld overlay repair commissioning is currently planned for late 2010

Industry First - Recent Weld Overlay Operating Experience and Response In late March the W(SI)2 team deployed to a Westinghouse unit to apply weld overlay to four (4) hot leg reactor vessel nozzles ndash an industry first Weld quality issues (identified by PT) were unexpectedly encountered while welding the nickel-based Alloy 52 weld filler material over the stainless barrier or lsquobufferrsquo layer (SS 308L) A buffer layer is installed over the stainless base materials as part of the weld overlay process if base material chemistry is determined to promote solidification cracking (hot cracking) Outage schedule concerns led the utility to decide to remove the weld overlay material that had been applied to that point and instead complete the MRP-139 inspection of the vessel nozzle dissimilar metal welds The W(SI)2 team predominantly utilized remote tooling to remove overlay material to the extent needed to support inspection activities The team also helped obtain NRC approval of weld overlay material left on several nozzles that would have otherwise required manual removal (and unnecessary dose and schedule)

Immediately following demobilization from site a Root Cause Analysis (RCA) team was assembled that consisted of representatives from the utility EPRI WSI and SI and The Ohio State University Boat samples removed from the field were used to confirm the issue to be solidification cracking Based on testing that was performed as part of the RCA the source of the solidification cracking was narrowed to the synergistic effects of several contaminant elements contained in the cast stainless base material

At the time of this writing the team continues to test welding methods that limit lsquodilutionrsquo of the contaminants into the Alloy 52 weld process A fairly broad range of base materials is available to the program through the involved utility and EPRI as well as third-party material suppliers The diverse material set of cast stainless materials is intended to bound the chemistries of materials expected to be encountered in large-bore weld overlay applications Weld overlay design changes are also being evaluated to increase stainless buffer material content which in turn minimizes and possibly eliminates the interaction of the Alloy 52 material with the contaminants contained in cast stainless materials

Almaraz Project Earlier this year W(SI)2 completed a lsquosix-packrsquo weld overlay project for Almaraz 2 a Westinghouse unit near Almaraz Spain The project was executed to plan in a total window of 138 days This is the 22nd similar pressurizer refurbishment project completed by the team (those involving all top-head and surge line weld overlays) None of the 22 projects involved a single rejectable defect requiring reweld A About similar six-pack overlay project is planned for Almaraz 1 this fall

Reactor Coolant Pump Alloy 600 Projects The W(SI)2 team has a backlog of projects related to the inspection mitigation and contingent repair of Reactor Coolant Pump (RCP) Alloy 600 (82182) welds at several BampW and CE-designed plants A variety of as-built configurations including interferences and abutting branch lines are input to both the tooling and the weld overlay design processes Detailed mock-ups simulating field conditions have been built and weld process validation is in process for these projects All base materials involved in these projects (including cast stainless materials) are being evaluated with respect to the weld process and design W(SI)sup2 is the team of Welding Services Inc requirements to minimize the potential for solidification cracking based on recent operating experience (WSI) and Structural Integrity Associates

Inc (SI) This 25-year partnership started Also included in these RCP projects are the engineering analyses required to be prepared to readily evaluate in-situ weld flaws if identified Leak-Before-Break (LBB) evaluations are also being performed to support the with weld overlay repair of BWR primary planned and contingent application of weld overlay to LBB licensed piping In the case of the one planned system welds (due to IGSCC damage) overlay project NRC approval of a License Amendment Request (LAR) is required prior to plant restart In recent years this team has set the

industry standard for the engineering W(SI)2 is planning a workshop at WSIrsquos Technology Center in Norcross Georgia (outside Atlanta) on January 19-20 2010 to showcase its engineering NDE and weld overlay technology applicable to licensing implementation and inspection RCP and other large-bore applications The program will include several seminars related to PWSCC of Alloy 600 component repairslicensing updates repair design and recent industry OE Additional details on the workshop will be provided in the near future on wwwstuctintcom

Vol No 27 SummerFall 2009 9

- -

-

-

- ~

-

ULtRasoNiC PHaseD aRRaY eXaMiNatioN oF BUtt-FUSIon JoIntS In HIGH-denSIty PoLyetHyLene

Caleb Frederick cfrederickstructintcom

To eliminate the challenges associated with metal piping the nuclear power industry is now selectively using High Density Polyethylene (HDPE) piping for non safety related applications and considering broader use of HDPE as it does not rust rot corrode tuberculate or support biological growth [1]

However the applicable Construction Codes do not provide rules for the examination and testing of piping constructed with HDPE material [1] To meet this need ASME Code Case N 755 was developed to be consistent with ASME Section III Class 3 requirements for nuclear power plant applications that do not require volumetric examination However volumetric examination could prove very valuable in obtaining regulatory acceptance for first installations of HDPE

To date the only example of this is Ameren Callaway plant in the US which recently installed approximately 1600 linear feet of 36shyinch diameter buried HDPE piping in a safety-related application To ensure the absence of subsurface fusion problems ultrasonic Timeshyof Flight Diffraction (TOFD) was used to examine joints in straight sections of pipe However TOFD has limitations For instance TOFD requires two probes in a Transmit-Receive configuration which must straddle the fusion With this configuration mitered joints cannot be easily inspected Phased Array by comparison only requires access from one side of the joint at a time therefore able to inspect both straight and mitered joints with ease

The technique developed by Structural Integrity Associates is optimized to inspecting up to 4 inch wall-thickness This technique uses a low frequency probe with wedge material velocity similar to that of the HDPE to cover from just above mid-wall to the inside-diameter (ID) surface and use a second probe of slightly higher frequency with wedge material velocity much slower than that of HDPE in order to take advantage of refracted angles sweeping from just below mid-wall to near the outside-diameter (OD) surface This provides an overlap of mid wall coverage with a combined coverage of the lower 99 of the fused joint with some energy reaching the OD surface

Recommended field practice is to perform automated scans then investigate areas of concern manually This provides one continuous scan (or can be broken into segments) with uniform probe positioning while recording indication locations that are saved as a permanent record

Imaging is an additional benefit with Phased Array as you can define different views prior to inspection which can be observed during ldquoliverdquo scanning or defined during analysis after the data has been recorded These additional views are B-Scan (side) C- Scan (top) D-Scan (end) and Polar (cylindrical side) which can be displayed either ldquocorrectedrdquo or ldquouncorrectedrdquo for the angle recorded [2]

Through continued laboratory testing and field trial opportunities ultrasonic Phased Array has shown great potential in its ability to volumetrically examine HDPE piping material

10 SummerFall 2009

[1] Naujock D Basavaraju C 2008 ldquoSafety Evaluation by the Office of Nuclear Reactor Regulation Relief Request No I3R-10 Third 10-Year Inservice Inspection Interval Union Electric Company Callaway Plant Unit1rdquo Docket No 50- 483 United States Nuclear Regulatory Commission Washington DC

[2] Moles M Davis M Magruder C Ciorau P 2005 Phased Array Technical Guidelines Useful Formulas Graphs and Examples RD Tech Corp Quebec City pp 5 79

Vol No 27

Computational Fluid dynamics

John Arnold Scott Rau Sean Hastings jarnoldstructintcom sraustructintcom shastingsstructintcom

Computational fluid dynamics (CFD) is one of the branches of fluid mechanics that uses numerical methods and algorithms to analyze and solve fluid flow problems Computers are used to perform the millions of calculations required to simulate the interaction of liquids or gases within surfaces defined by boundary conditions Structural Integrity Associates (SI) is actively using CFD finite element models to aid in solving tough technical problems A few of our recent applications include flow analysis of feedwater systems economizers reheaters and other industrial process heaters Some of the relevant damage mechanisms being interrogated include Flow Accelerated Corrosion (FAC) and thermally induced damage In addition CFD techniques are used for design validation

For feedwater systems SI has developed several system CFD models using Flow Simulation The model geometry is generated using Solid Works a parametric solid modeling package and Flow Simulation to generate the CFD model Once models are compiled and solved appropriate parameters such as velocity including directional bulk and radial components can be displayed (see Figure 1)

Figure 1 (Velocity profile of a feedwater system)

Design validation of components is also another CFD analysis that SI performs Economizers in HRSG (heat recovery steam generator) units under certain conditions and material properties can be vulnerable to flow related damage mechanisms such as FAC SI offers nucleic boiling models integrated with expert metallurgical review of components experiencing single phase and two phase FAC damage Figures 2 3 and 4 show the validation of a flow straightening perforated plate design that was added to several economizers experiencing tube failures as a result of FAC In conclusion CFD modeling of power plant components is a very powerful tool that can be applied

Figure 2 (Flow profile in as-found condition)

Figure 3 (Diffuser plate added to inlet)

to solve many tough technical problems CFD analysis fits well into the integrated services that Figure 4 (Flow profile with proposed diffuser)SI offers through our staff expertise in materials mechanics and nondestructive testing We are continuing to explore other areas where CFD modeling can be successfully applied to resolve client reliability availability and safety concerns

Vol No 27 SummerFall 2009 11

rsquo

rsquo ndash

InteGRIty MAnAGeMent SUPPoRt FoRGAS dIStRIBUtIon oPeRAtoRS

Scott Riccardella sriccardellastructintcom

Structural Integrity Associates is preparing to support natural gas distribution system operators compliance with new Federal regulations that extend integrity management practices to the largest segment of the Nation s pipeline network the gas distribution systems that deliver gas directly to homes and businesses

Beginning in 2000 the Department of Transportationrsquos Pipeline amp Hazardous Materials Safety Administration (PHSMA) issued rulemaking that requires operators of hazardous liquid pipelines and gas transmission pipelines to develop and follow individualized integrity management programs The approach involves continuous improvement in pipeline safety by requiring operators to analyze their pipelines and identify and manage factors that affect risk Structural Integrity Associates has supported pipeline operators compliance with these requirements with Integrity Management Plans Direct Assessment Procedures Risk Models and general program support

Coming Soon

Eric Kirkpatrick ekirkpatrickstructintcom

This Fall the PHMSA is scheduled to issue Final Rulemaking on Gas Distribution Integrity Management commonly referred to as DIMP (Distribution Integrity Management Program) The rule will require each operator of a gas distribution system to fully implement a program within 18 months that contains the following elements

bull Knowledge bull Identify Threats bull Evaluate amp Prioritize Risk bull Identify amp Implement Measures to address

Risks bull Measure Performance Monitor Results and

Evaluate Effectiveness bull Periodic Evaluation amp Improvement bull Report Results

Structural Integrity Associates will provide products and services to support operatorrsquos implementation of DIMP SI has partnered with the Northeast Gas

Association and the Southern Gas Association to produce a written DIMP Program that can be customized for operators 47 companies collectively serving 43 of the gas customers in the US have already committed to purchase the Structural Integrity Associates DIMP Program Structural Integrity will also be supporting clients with training auditing written plan customization risk analysis annual threat re-evaluation mitigation plans and turn-key program support

For more information please contact Eric Kirkpatrick ekirkpatrickstructintcom or Scott Riccardella sriccardellastructintcom

Vol No 27 12 SummerFall 2009

InteGRIty MAnAGeMent SUPPoRt FoRGAS dIStRIBUtIon oPeRAtoRS

Martin Romero mromerostructintcom

Structural Integrity Associates (SI) recently completed a project to evaluate thermal stratification in a pressurized water reactor (PWR) pressurizer surge line using computational fluid dynamics (CFD) software Thermal stratification may occur in nuclear power plant piping when buoyancy forces act to maintain a separation between slow moving or stagnant fluids of differing temperatures (ie densities) This is common in the operation of a pressurizer surge line because interaction between the hot pressurizer water and the relatively cooler reactor coolant system (RCS) water can occur in this line during the normal operation of the plant The resulting thermal stratification causes localized thermal stresses due to the local temperature gradients and causes global bending due to the difference in thermal expansion in the upper and lower portions of the pipe Thermal stratification can cause issues ranging from excessive pipe displacement to thermally induced fatigue cracking

The objective of the project was to develop surge line temperature profiles which bound the various insurge and outsurge flows associated with each design transient SI developed a method to screen 27 Service Level A and B design transients for the possibility of thermal stratification Of these transients 8 were identified to require further analysis since it was determined that thermal stratification was a possibility Of these remaining transients 3 insurge flows and 3 outsurge flows were found to bound all 8 transients and were modeled in ANSYS CFX

The figure adjacent illustrates the temperature contours at the interface between the modeled pipe and fluid and shows a snapshot in time as cooler RCS fluid flows into a surge line towards the pressurizer Temperature and flow information can

Vol No 27

evaLUatioN oF sURge LiNe tHeRMaLstRatiFiCatioN witH C o M P U tAt I o n A L

F LU Id dynAMICS

be extracted at any pipe cross-section for further analysis An alternate time saving technique The method was verified using CFD best is to transfer solid temperatures directly to practice guidelines for simulation of reactor ANSYStrade Mechanical to perform a structural safety applications in conjunction with SIrsquos analysis CFD simulation also provides a Quality Assurance program benefit over traditional methods which require that the structural analyst make conservative For more information please contact Martin assumptions regarding how to model thermal Romero at mromerostructintcom stratification height and temperature profiles Typically stress analysis of thermal stratification loads assumes the top half of the pipe is hot and the bottom half of the pipe is cold this is known as a 5050 profile The CFD simulation produces a representation of the thermal profile that can be used in stress analysis which removes conservatism from the 5050 profile Finally CFD can be used to redesign piping to eliminate or minimize thermal stratification altogether

Pressurizer Insurge During Heatup

SummerFall 2009 13

Karen Fujikawa kfujikawastructintcom

High temperature Strain Gage Installation and Monitoring Monitoring creep rates in high temperature components can provide valuable life assessment information to power plant operators High temperature capacitive strain gages (SGs) were installed on main steam piping at an HRSG plant Two large diameter hot reheat elbows were instrumented at two locations each Additionally a straight section of pipe was instrumented for comparison and thermocouples were also installed at each location Structural Integrity (SI) developed a customized Creep Data Acquisition System (CDAS) to perform the data collection and transmission of data to the plant computer The CDAS has the capability to control multiple signal conditioners each with multiple channels to process Signal measurements are taken with an integrated high precision digital multi-meter The versatility of the CDAS accommodates the need for application-specific customization due to the complex nature of creep strain monitoring instrumentation

Fatigue Failure of a Feedwater Pipe Support A piping support on a moisture separator reheater (MSR) drain line from a feedwater heater was found broken The line had been subject to large low frequency vibration displacements caused by pressure pulsations Although the pipe supports on this line had been inspected and repaired the piping itself had not been evaluated to determine whether the cyclic displacements were causing excessively high fatigue damage A piping analysis was performed that assessed the stress levels in the piping determined the critical locations and compared the stresses to the endurance limit Displacement measurements

Vol No 27

VIBRAtIon were taken at key points in the piping system so that the mode shape of the displacement could be described analytically A detailed piping model was created and a dynamic modal analysis was performed The analysis calculated the mode shapes and natural frequencies of the piping The vibration input was tuned so that the displacement results would match the measured displacements In this way it was possible to determine the range of modal frequencies that were responding to the pressure wave Once the modal response was determined the piping stresses due to vibration were calculated The stresses were then evaluated against the material endurance limit to determine acceptability The result was that the vibration stress levels were indeed unacceptable A modification was proposed and the analysis was rerun demonstrating that the modification will be successful in reducing the vibration stresses to an acceptable level

edG Lube oil Piping evaluation and design Improvements During a scheduled surveillance test a leak in a lube oil line to one of the station emergency diesel generators (EDGs) was discovered SI was contacted to assist the station in establishing the cause of the failure and help develop and implement actions to prevent recurrence SI assisted the plant with developing a Failure Modes and Effects Analysis performed laboratory analysis of the failed elbow joint and collected and analyzed vibration data on the piping and engine which identified a resonance condition that resulted in a high cycle fatigue failure Engineering models were developed to help establish the root cause(s) of the failure and evaluate the capability of the EDG to operate throughout its required mission time The collected field vibration data was used to validate a finite element model The forces and moments from the finite element model will be used to perform a fracture mechanics crack growth calculation and to develop an estimate of leakage over time Using this information SI

CoRneR assisted the station with developing a modified piping design to prevent future failures and collected post-modification vibration data which confirmed the effectiveness of the design change Based on this work SI is working with the station to develop screening criteria that can be used during normal vibration monitoring to confirm the system will not experience similar failures in the future

SIrsquos CDAS at Bayside Power Station with SI Engineers Roland Horvath (left) and Clark Oberembt (right)

SummerFall 2009 14

TRAINING ON HIGH ENERGY PIPING INSPECTIONS

Harold E Queen hqueenstructintcom

Laney Bisbee lbisbeestructintcom

High energy piping systems in coal-fired power plants operate at high temperatures which can lead to creep damage formation after an extended period of operation ultimately leading to component failure Detection and characterization of the damage with respect to location depth of crack degraded material and operating history are critical for planning scheduling and implementing remedial solutions Early detection is key to avoid catastrophic failure which could result in an extended shut down until a replacement component can be fabricated and installed These extended and unplanned outages result in several million dollars of revenue lost Periodic systematic assessments carried out with state-of-the art inspection technologies provides a benchmark so that a trend of the deterioration if present can be made providing an important piece of information for estimating creep damage

Creep is time and temperature dependent and the limits for creep are well established for different materials A comprehensive inspection protocol as part of the broader scope of plant asset management is essential for any utility to maintain safety reliability and availability It is also important for efficiency enhancement since damaged components can cause undesirable steam leaks and non optimal operation Inspection data also contributes to the information necessary to plan a major component replacement in critical areas such as piping steam headers hangers and supports

Vol No 27

In November 2008 Structural Integrity participated in the Power Plant Summit and Service Providers Workshop hosted by United States Agency for International Development (USAID) National Energy Technology Laboratory (NETL) and the Confederation of Indian Industries (CII) SI presented a technical paper and an exposition on Key Considerations in Asset Management of Critical Power Plant Components SIrsquos participation was well received by the leading utilities in India and by the Central Electricity Authority the technical arm of the Ministry of Power As a result National Thermal Power Corporation (NTPC) took the lead in approaching USAID to organize a three day training workshop at one of the NTPC plants under the USAID-NETL Participating Agency Service Agreements (PASA) The overall objective of the training was to provide hands-on training and knowledge transfer on inspection technologies and evaluation of critical high energy plant components

On June 30th through July 2nd 2009 a three day workshop was held and attended by 41 participants at the NTPC Vindhyachal fossil power station Presentations and detailed discussions on the various engineering inspection organizational documentation and management components of a High Energy Piping Program were provided by Laney Bisbee and Harold Queen as part of the three day workshop Discussions included the management and organizational requirements necessary to implement an effective piping program within a large electric utility including the key metallurgical engineering analysis and nondestructive capabilities required in such a program

In addition to the presentations a hands-on demonstration of advanced ultrasonic equipment was provided during the workshop including Time-of-Flight Diffraction Linear Phased Array and Annular Phased Array equipment and technique demonstrations for piping and tubing welds

The presentations were supplemented with an actual walk-down of a portion of the main steam hot reheat and cold reheat piping systems of the Vindhyachal Unit 7 power plant concentrating on a visual inspection of the hanger systems After the completion of the workshop on July 2nd discussions were held with the Vindhyachal General Manager covering the observations of the plant hanger walk-down as well as the engineering and inspection requirements for a high energy piping program

SummerFall 2009 15

11515 Vanstory Drive Suite 125 Huntersville NC 28078

2009 events

Structural Integrity WEBINAR Introduction to Stress Corrosion Cracking September 30 200 pm ET

Structural Integrity WEBINAR Life Management Issues for Creep Strength Enhanced Ferritic Steels October 14 200 pm ET

Structural Integrity WEBINAR Introduction to Nuclear Plant Services October 21 200 pm ET

CNS Steam Generator Conference Toronto ON November 8-11

Structural Integrity WEBINAR High Density Polyethylene Pipe Non-Destructive Examination November 11 200 pm ET

Structural Integrity WEBINAR Metallurgy of Alloy 52M Dissimilar Metal Welds December 9 200 pm ET

2010 events January-March

EPRI Winter TG Technical Workshop and Users Group (TGUG) Meeting and Vendor ExpoWilliamsburg VA January 18-19

Energy Generation Conference Bismarck ND January 26-28

Structural Integrity WEBINAR Fundamentals of Welding ndash Part 1 February 3 200 pm ET

Structural Integrity WEBINAR Fundamentals of Welding ndash Part 2 February 10 200 pm ET

CNA Annual Conference amp Tradeshow Ottawa ON February 24-26

Structural Integrity WEBINAR Computational Fluid Dynamics March 3 200 pm ET

NACE Corrosion 2010 San Antonio TX March 14-18

COMING SOON SIU Structural Integrity Associates will be hosting a series of training courses in June and August 2010 called

Structural Integrity University Mark your calendars now and look for more information soon

For more information on these events and Structural Integrity go to wwwstructintcom

Annapolis MD Austin TX Charlotte NC Chattanooga TN Chicago IL Denver CO 410-571-0861 512-533-9191 704-597-5554 423-553-1180 815-648-2519 303-792-0077

Los Angeles CA Salt Lake City UT San Jose CA Stonington CT Toronto Canada Uniontown OH562-402-3076 801-676-0216 408-978-8200 860-536-3982 905-829-9817 330-899-9753