News and Views Archives

News & View, Volume 44 | Data Driven Solutions for the Most Difficult Problems

News & Views, Volume 44 | Data Driven Solutions for the Most Difficult Problems

April 27, 2018/in Andrew Crompton, Fracture Mechanics, Mark Jaeger, News and Views, Nuclear Asset Integrity, Nuclear Energy, Vibration/by Structural Integrity

By: Andrew Crompton and Mark Jaeger

In recent years, SI has observed an increasing trend in the use of specialty instrumentation to solve “impossible” problems or answer “indecipherable” questions. This shift was particularly apparent within commercial nuclear, where data-driven solutions have long been perceived as challenging due to short outage windows, personnel dose concerns, and a significant paperwork burden, among other factors. Widespread adoption of instrumentation-based solutions creates new paths to tackling difficult/persistent problems, and shifts the industry focus for critical assets from reactionary to more of a predictive approach. In 2017, SI assisted numerous clients with deployment of specialty instrumentation in this fashion, comprising two general scenarios: 1) new designs/modifications, and 2) repeat failures. Each application requires different sensors and varying analytical methods, but the approach used to leverage the resultant data to solve the problem is generically applicable throughout the energy sector. The text below details important considerations for both scenarios and highlights a successful application of the underlying process for management of thermal fatigue in reactor coolant system branch piping.

News & Views, Volume 44 | Update on Proposed Safety of Gas Transmission and Gathering Pipeline Regulation

April 27, 2018/in Bruce Paskett, Eric Fisette, News and Views, Oil and Gas Pipeline, Scott Riccardella/by Structural Integrity

By: Scott Riccardella, Erica Fisette, and Bruce Paskett

Structural Integrity (SI) has significant depth and expertise in current pipeline safety regulations and dedicates substantial resources to ensure a comprehensive understanding of proposed pipeline safety regulations. Using the most current insights relative to upcoming regulations, Structural Integrity guides our clients with strategic direction to best position their pipeline safety programs to comply with the new regulations. Structural Integrity takes a proactive role in attending key Pipeline and Hazardous Materials Safety Administration (PHMSA) meetings such as the Gas Pipeline Advisory Committee (GPAC) meetings as well as supporting the rulemaking efforts of the American Gas Association (AGA), Interstate Natural Gas Association of America (INGAA), Pipeline Research Council International (PRCI) and other key associations.

The GPAC is a statutorily mandated Committee that advises PHMSA on proposed gas pipeline safety standards and regulations. The Committee consist of members from Federal and State governments (PHMSA and National Association of Pipeline Safety Representatives or NAPSR), the regulated industry, and the general public. The Committee is responsible for reviewing the technical feasibility, reasonableness, cost-effectiveness, and practicability of proposed standards and regulations relative to pipeline safety. The goal of the Committee is to provide recommended revisions and/or actions in response to standards and/or regulations proposed by the Federal Department of Transportation (DOT)/ PHMSA.

News & Views, Volume 44 | A First-of-a-Kind NDE Innovation from SI – The first PDI qualified manually-encoded DM weld procedure

April 27, 2018/in Jason Van Velsor, LATITUDE, News and Views, Non-Destructive Evaluation, Nuclear Asset Integrity/by Structural Integrity

By: Jason Van Velsor, Joe Agnew, and Owen Malinowski

Determining a course of action once in-service damage is discovered often requires applying a multi-disciplinary approach that utilizes Nondestructive Examination (NDE), analytical techniques such as stress analysis, and metallurgical lab examination. Such was the case recently for a combined cycle plant where indications were found through NDE on the inlet sides of two identical main steam stop/control valves but were not seen on the outlet side. In this case, Structural Integrity (SI) did not perform the field NDE but was requested to perform analytical and metallurgical assessments of the welds. The welds in question joined the 1Cr-1Mo-1/2V (SA-356 Grade 9) main stop/control valve body castings to Grade 91 piping, so the welds represent a ferritic-to-ferritic dissimilar metal weld (DMW). See the Dissimilar Metal Welds in Grade 91 Steel, (page 15) for further information. The welds were made using a 1Cr-1/2Mo (AWS type B2) filler metal, which matches the chromium content of the valve body, but is significantly undermatching in strength to both the valve body material and the Grade 91 piping.

The course of action taken was to perform local stress analysis and remaining life estimates for the downstream (outlet) connections of the valves to assess likelihood of future damage and establish an appropriate re-inspection interval. Detailed metallurgical analysis was also performed on a ring (entire circumference) section removed from one of the upstream welds (which exhibited both surface and volumetric indications in the weld metal) in order to provide insight into the damage mechanism and inform the stress analysis and remaining life estimates.

News & Views, Volume 44 | Example Grade 91 High Energy Piping DMW Joint Stress and Metallurgical Analysis

April 27, 2018/in Ben Ruchte, Materials Laboratory, News and Views/by Structural Integrity

By: Ben Ruchte

Determining a course of action once in-service damage is discovered often requires applying a multi-disciplinary approach that utilizes Nondestructive Examination (NDE), analytical techniques such as stress analysis, and metallurgical lab examination. Such was the case recently for a combined cycle plant where indications were found through NDE on the inlet sides of two identical main steam stop/control valves but were not seen on the outlet side. In this case, Structural Integrity (SI) did not perform the field NDE but was requested to perform analytical and metallurgical assessments of the welds. The welds in question joined the 1Cr-1Mo-1/2V (SA-356 Grade 9) main stop/control valve body castings to Grade 91 piping, so the welds represent a ferritic-to-ferritic dissimilar metal weld (DMW). See the Dissimilar Metal Welds in Grade 91 Steel, (page 15) for further information. The welds were made using a 1Cr-1/2Mo (AWS type B2) filler metal, which matches the chromium content of the valve body, but is significantly undermatching in strength to both the valve body material and the Grade 91 piping.

The course of action taken was to perform local stress analysis and remaining life estimates for the downstream (outlet) connections of the valves to assess likelihood of future damage and establish an appropriate re-inspection interval. Detailed metallurgical analysis was also performed on a ring (entire circumference) section removed from one of the upstream welds (which exhibited both surface and volumetric indications in the weld metal) in order to provide insight into the damage mechanism and inform the stress analysis and remaining life estimates.

News & View, Volume 44 | Planned and Emergent Outage Support Structural Integrity is on Your Team

News & Views, Volume 44 | Planned and Emergent Outage Support – Structural Integrity is on Your Team

April 27, 2018/in News and Views, Nuclear Asset Integrity, Nuclear Energy, Nuclear Outage, Terry Herrmann/by Structural Integrity

By: Terry Herrmann

While the 2018 Spring outage season is mostly behind us, we all know a key element in being able to provide safe, reliable, clean and economic power to energy consumers is how successfully plant outages are accomplished. I know from personal experience how good planning, including contingency planning, has significantly reduced outage durations (see Figure 1). I worked my first outage in 1981. It ran 110 days and was punctuated by rework, surprise discoveries and last-minute procurement of materials and services. By the late 1990s the industry had established outage milestones for design changes, significantly improved the level of detail in schedules, performed more work with the plant on line and implemented focused outage control organizations. Except for major activities like condenser retubing, power uprates and emergent issues that impact the scheduled critical path, outage durations today are almost exclusively associated with refueling activities.

News & Views, Volume 44 | Metallurgical Lab Featured Damage Mechanism – Long-Term Overheating/Creep (LTOC) in Steam-Cooled Boiler Tubes

April 27, 2018/in Materials Laboratory, News and Views, Terry Totemeier/by Structural Integrity

By: Terry Totemeier

Long-term overheating and creep damage are often the damage mechanisms associated with the normal or expected end of life of steam-touched tubes, generally occurring after 100,000 hours or more of service life at elevated temperatures and pressures. Long-term overheating and creep can also occur when the rate or accumulation of creep damage is moderately higher than anticipated by original design. There are a number of possible reasons for this, but in general the problem can be attributed to one of the following: a non-conservative original design, higher-than-anticipated heat absorption, lower-than-anticipated steam flow, or wall loss caused by external wastage.

Mechanism
The mechanism of failure for LTOC is simply the accelerated accumulation of creep damage in the component over a span of time that is well short of the anticipated design life, but sufficiently long that creep is the dominant damage mode. This damage is typically associated with the operation of the tube above the oxidation limit for the material involved. This has two effects, which both contribute to long-term creep failure: reduction in wall thickness due to oxidation loss, and build-up of oxide on the tube internal surface, which insulates the tube from the cooling effect of the steam, leading to increasing tube metal temperatures over time.

News & Views, Volume 44 | Integrated Flow Distributors (IFD)

April 27, 2018/in Al Jarvis, Chemistry, Edward Dougherty, News and Views, Nuclear Energy/by Structural Integrity

By: Ed Dougherty and Al Jarvis

for Bottom Tubesheet Filter/Demineralizers Initial Installation and Performance at Browns Ferry Nuclear StatioThe Browns Ferry Nuclear Station (BFNS) intends to implement an extended power uprate (EPU) at all three units beginning in 2018 for Unit 3 and Unit 1, and in 2019 for Unit 2. EPU implementation will increase the total thermal power of each unit by 494 MWth resulting in a total uprate of 20% from the originally licensed thermal power of 3293 MWth.

Each BFNS unit is currently designed with ten bottom tubesheet condensate filter/demineralizers (CF/Ds) in the condensate treatment system that require an application of a powdered resin precoat to perform the function of demineralization. The precoat material is applied as an overlay on top of vertical filter septa. The filter septa have an inner pleated area, and with a precoat overlay, perform the function of demineralization as well as particulate iron removal. In the absence of circulating water leakage into the condenser, the primary function of the CF/Ds is to remove particulate iron that collects in the condenser hotwell. The iron source is from the corrosion of carbon steel piping and components in contact with main steam and heater drain systems.

News & Views, Volume 44 | Strategic Internal Corrosion Monitoring for Gas Pipelines

April 27, 2018/in Corrosion, Lance Barton, Monitoring, News and Views, Oil and Gas Pipeline/by Structural Integrity

By: Lance Barton and Tom Pickthall (EnhanceCo)

REGULATORY OVERVIEW
A March 16, 2017, advisory bulletin (Docket No. PHMSA-2016-0131 – “Pipeline Safety: Deactivation of Threats”) gave guidance on the deactivation of pipeline threats, including the threat of internal corrosion. On April 8, 2016, PHMSA issued a Notice of Proposed Rulemaking (NPRM) entitled “Safety of Gas Transmission and Gathering Pipelines”. Section §192.478 “Internal Corrosion Control: Onshore transmission monitoring and mitigation” of the NPRM would increase the scrutiny and requirements for monitoring and mitigating the threat of internal corrosion for the gas industry.

This bulletin and NPRM reinforce the requirements of CFR part 192-subpart O, Section 192.937, requiring gas pipeline operators to continuously assess their pipelines for the threat of internal corrosion as part of their overall integrity management program. One of the requirements is to determine if the gas entering the system is corrosive or not corrosive. The optimal way to prove that the gas is not corrosive is to build a thorough continuous monitoring program that considers guidance from the NPRM and the advisory bulletin.

News & Views, Volume 44 | Dissimilar Metal Welds in Grade 91 Steel

April 27, 2018/in Materials Laboratory, News and Views, Terry Totemeier/by Structural Integrity

By: Terry Totemeier

Introduction
A dissimilar metal weld (DMW) is created whenever alloys with substantially different chemical compositions are welded together – for example, when a low-alloy steel such as Grade 22 (2¼ Cr-1Mo) is welded to an austenitic stainless steel such as TP304H (18Cr-8Ni). Many DMWs are commonly present in fossil-fired power plants, examples being material transitions in boiler furnace tubes, stainless steel attachments welded onto ferritic steel tubes or pipes, and stainless steel thermowells or steam sampling lines in ferritic steel pipes. The chemical composition gradients associated with DMWs present unique issues relative to their design, in-service behavior, and life management, particularly for those DMWs operating at elevated temperatures where solid-state diffusion and cyclic thermal stresses are factors, which was previously presented in News and Views (Volume 43, page 19).

With the now widespread use of Grade 91 steel (9Cr-1Mo-V-Nb) for elevated-temperature applications in modern power plants, DMWs involving this material have become common, and increasing service experience has revealed some unique characteristics and failure mechanisms, especially in thicker-section DMWs with austenitic materials. This article presents a short overview of Grade 91 DMWs: their design, fabrication, and failure, with emphasis on current industry issues.

There are two basic classes of DMWs in Grade 91 steel: ferritic-to-ferritic and ferritic-to-austenitic. The first type corresponds to Grade 91 welded to another ferritic steel with a lower chromium content, such as Grade 22; the second type corresponds to Grade 91 welded to an austenitic stainless steel such as TP304H. Each of these types has unique concerns and considerations.

News & Views, Volume 44 | Real-Time Damage Tracking with SI Technology and GP Strategies’ EtaPro

April 27, 2018/in Fossil Power, Matt Freeman, Monitoring, News and Views, PlantTrack/by Structural Integrity

By: Matt Freeman

Expanding Capabilities in Condition-based Pressure-part Integrity Management

Structural Integrity and GP Strategies recently announced an agreement to bring SI’s technology for calculating, tracking, and trending life consumption of piping and boiler components to GP Strategies EtaPRO real-time monitoring platform (Press release here). SI has a long history with creep and fatigue damage monitoring applications, most recently with the suite of applications available as part of SI’s PlantTrack platform. The partnership with GP Strategies brings that technology to EtaPRO, which is used worldwide by power-generating organizations to monitor the performance and reliability of their generation assets.

EtaPRO users will benefit from easy integration of SI’s leading-edge Boiler and Piping Component Reliability (BPCR) modules to quantify damage to high-pressure, high-temperature components such as tubing, piping, headers, and desuperheaters. The BPCR modules track and trend accumulated creep and fatigue damage in real time using SI’s proprietary algorithms that combine actual operating data and material condition with a plant’s specific configuration. Plant operators can use the resulting life consumption estimates to guide asset management decisions, such as changes in operating procedures, targeted inspections, or off-line analysis of anomalous conditions.