News - Page 16 of 16 - Structural Integrity Associates

News & Views, Volume 43 | Wind Project Continued Operation Beyond Designed Life

October 5, 2017/in News and Views, Wind Power/by Structural Integrity

By: Ceci Wilson

With the increase of renewable energy into the power generation market, aggressive state renewable targets, and recently renewed production tax credit (PTC), wind power generation demand is positioned to increase significantly. This is good news not only for new wind projects but also for existing wind power infrastructure.

As the wind energy market and demand has grown quickly, so has the technology – better turbine controls, more efficient drivetrains, longer and lighter blade designs, and taller towers. Figure 1 shows that in 2000 wind turbines had an average nameplate capacity of slightly less then 1 MW and 30% capacity factors, while the average nameplate capacity in 2016 was 2.15 MW ^[1], with capacity factors near 40%. Blade lengths of 25 meters in 2000 are dwarfed by the more recent 50 meter blades (see Figure 2). Longer blades at higher hub heights and more efficient controls means that new wind projects can achieve more power generation capacity with half (or less) the number of turbines compared to 10-year-old projects.

A typical wind turbine is designed for 20-year operation. In 2017, most of the US wind turbine fleet is less than 10 years old, with 20% of the fleet between 10 and 16 years of age. As wind turbines age and near their design life of 20 years, owners should start assessing their future options for continued operation:

Partial repowering: Would it be beneficial to invest in upgrades that take advantage of new technology to increase power generation and/or turbine life?
Repowering: Given technology development, is it better to replace existing wind turbines with new ones?
Life extension: Can the operating wind turbines continue operating past 20 years as-is (or with minor adjustments)?

The answers to these questions are project and site specific.

News & Views, Volume 43 | Managing Fatigue-Challenged Components in SLR

October 5, 2017/in News and Views, SI:FatiguePro/by Structural Integrity

By: Jennifer Correa

Subsequent License Renewal (SLR) will require a shift in the approach for managing plant components for thermal fatigue. The components are older and will have experienced more fatigue damage. As time goes on, more components will become fatigue-challenged, meaning that they will require more management to demonstrate serviceability.

There are several approaches that can be taken to manage fatigue-challenged components in SLR.

Refining the design fatigue analyses is one approach that has been widely used in License Renewal (LR), and will remain useful in SLR. Components that were previously managed through cycle counting alone may still be managed through cycle counting if a refined analysis results in fatigue and environmentally-assisted fatigue (EAF) cumulative fatigue usage values below 1.0.

Another useful approach is to revisit assumptions made about plant operation earlier in life. Conservative assumptions were made about early plant operation for many components. This was often done for expediency and may have been sufficient for LR, but as the components age, those assumptions may prove too conservative. Revisiting these assumptions can help lower the overall fatigue usage for components.

News & Views, Volume 43 | Advanced Structural Analysis

October 5, 2017/in Complex Loadings, Critical Structures, Eric Kjolsing, Hydroelectric Power, News and Views, Structural Assessments/by Structural Integrity

By: Eric Kjolsing & Philip Voegtle

News & View, Volume 43 | Advanced Structural Analysis The sophistication of structural analysis has evolved side-by-side with computing and graphics technology. Structural engineers have at their fingertips very powerful software analysis tools that assist them in evaluating very large and complex structures for stability, suitability, and code adequacy. The tools themselves vary in complexity in proportion with the engineering analysis required of them – the most complex and unique engineering problems requiring the most advanced analysis tools. Structural Integrity is a leader in advanced structural analysis (ASA), utilizing state-of-the-art software and material science expertise to solve an array of structural and mechanical problems.

Structural analysis, in its most basic definition, is the prediction of the structural performance of a given structure, system, or component to prescribed loads, displacements, and changes in temperature. Common performance characteristics include material stresses, strains, forces, moments, displacements and support reactions. The results from a structural analysis are typically compared to acceptable values found in design codes. Meeting the design code acceptance criteria ensures a design that protects the public’s health, safety, and welfare.

ASA extends this basic definition of structural analysis to one-of-a-kind problems where the acceptance criteria may not be well defined. Since loads, material behavior, or the structure itself can go beyond the scope of basic design codes, ASA requires an in-depth understanding of modeling techniques, software limitations, and non-linear material behavior. In ASA, sophisticated finite element analysis solvers are utilized to gain a detailed understanding of a system’s non-linear mechanical behavior, providing a full three-dimensional view of the critical stresses and strains in a loaded system.

News & Views, Volume 43 | A Strategic Approach for Completing Engineering Critical Assessments of Oil and Gas Transmission Pipelines

October 5, 2017/in News and Views, Oil and Gas Pipeline, Scott Riccardella, Steven Biles/by Structural Integrity

By: Scott Riccardella and Steven Biles

Regulatory Overview
In January 2012, the Pipeline Safety, Regulatory Certainty, and Job Creation Act of 2011 was signed into law directing PHMSA to take steps to further assure the safety of pipeline infrastructure. PHMSA issued the related Notice of Proposed Rulemaking (NPRM) for Safety of Gas Transmission and Gathering Pipelines on April 8, 2016. Included in the NPRM were significant mandates regarding:

Verification of Pipeline Material (§192.607); and
Maximum Allowable Operating Pressure (MAOP) Verification or “Determination” (§192.624)

The NPRM proposes requirements for operators to verify the MAOP of a gas transmission pipeline when:

The pipeline has experienced an in-service incident (as defined by §191.3) due to select causes¹ in a High Consequence Area (HCA), “piggable” Moderate Consequence Area (MCA), or Class 3 or 4 location since its last successful pressure test
The pipeline lacks Traceable, Verifiable, and Complete pressure test records for HCAs or Class 3 or 4 locations
The pipeline MAOP was established by the grandfather clause (§192.619 (a)(3)) for HCAs, “piggable” MCAs, or Class 3 or 4 locations.

To verify the MAOP of a pipeline, the NPRM provides the following options:

Method 1: Pressure Test
Method 2: Pressure Reduction
Method 3: Engineering Critical Assessment (ECA)
Method 4: Pipe Replacement
Method 5: Pressure Reduction for segments with small potential impact radius (PIR) & diameter
Method 6: Use Alternative Technology

The ECA Approach
Per the NPRM, Method 3 (ECA) is defined as an analysis, based on fracture mechanics principles, material properties, operating history, operational environment, in-service degradation, possible failure mechanisms, initial and final defect sizes, and usage of future operating and maintenance procedures to determine maximum tolerable sizes for imperfections.

News & Views, Volume 43 | LATITUDE™ Innovating the NDE Data Acquisition Process

October 5, 2017/in Jason Van Velsor, LATITUDE, News and Views, Non-Destructive Evaluation/by Structural Integrity

By: Jason Van Velsor

From the creation of the first simple stone tools to the invention of the world wide web, technological innovation has been the undercurrent that has carried the human species from our primitive survivalist ways to our present-day complexity of modern conveniences. We innovate from necessity, competition, or from a desire for an improved quality of life. Innovation has been and remains key to our survival and proliferation.

In business, it is no different and innovation has been a mainstay at Structural Integrity and part of our core values since our inception in 1983. We are constantly developing and applying innovative practices and technologies to meet our clients’ toughest challenges and to provide best-in-value solutions. In this spirit, we are excited to announce one of our most recent innovations, LATITUDE^TM.

LATITUDE is a non-mechanized position and orientation encoding technology designed for use with nondestructive evaluation (NDE) equipment. Simply stated, LATITUDE enables an operator to manipulate a probe by hand while maintaining a digital record of the position and orientation of the probe at all times. For many applications, LATITUDE can be thought of as a fast and compact alternative to cumbersome and complicated automated inspection equipment.

News & Views, Volume 43 | Using Falcon to Develop RIA Pellet-Cladding Mechanical Interaction (PCMI) Failure Criteria

October 5, 2017/in John Alvis, News and Views, Nuclear Fuel, Reactor/by Structural Integrity

By: John Alvis

Introduction
The goal to achieve higher fuel rod burnup levels has produced considerable interest in the transient response of high burnup nuclear fuel. Several experimental programs have been initiated to generate data on the behavior of high burnup fuel under transient conditions representative of Reactivity Initiated Accidents (RIAs). A RIA is an important postulated accident for the design of Light Water Reactors (LWRs). It is considered the bounding accident for uncontrolled reactivity insertions.

The initial results from RIA-simulation tests on fuel rod segments with burnup levels above 50 GWd/tU, namely CABRI REP Na-1 (conducted in 1993) and NSRR HBO-1 (conducted in 1994), raised concerns that the licensing criteria defined in the Standard Review Plan (NUREG-0800) may be inappropriate beyond a certain level of burnup. Figure 1 is an example of a typical high burnup fuel cladding showing the oxidized and hydrided cladding of higher burnup fuel rods. Figure 2 shows the typical radial crack path in oxidized and hydrided cladding, subjected to RIA simulation tests. As a consequence of these findings, EPRI with the assistance of the Structural Integrity’s Nuclear Fuel Technology Division (formally ANATECH) and other nuclear industry members conducted an extensive review and assessment of the observed behavior of high burnup fuel under RIA conditions. The objective was to conduct a detailed analysis of the data obtained from RIA-simulation experiments and to evaluate the applicability of the data to commercial LWR fuel behavior during a Rod Ejection Accident (REA) or Control Rod Drop Accident (CRDA). The assessment included a review of the fuel segments used in the tests, the test procedures, in-pile instrumentation measurements, post-test examination results, and a detailed analytical evaluation of several key RIA-simulation tests.

News & Views, Volume 43 | TRU Compliance: The Standard for Seismic, Wind, and Blast Certification

October 5, 2017/in Andy Coughlin, News and Views, TRU Compliance/by Structural Integrity

By: Andy Coughlin

About TRU COMPLIANCE

As the product certification arm of Structural Integrity, TRU Compliance stands for safety and code compliance when failure is not an option. Our clients manufacture cutting edge products that push the limits of operational performance and efficiency in many industries. We help them achieve continued performance during earthquakes, high wind events, explosions, and a host of other extreme events.

At TRU Compliance, we believe that achieving code compliance in these areas should not be complicated. So, we continually invest in the development of innovative systems and approaches to simplify the lives of our clients and deliver efficient and transparent results, every time.

TRU Compliance is a recognized leader in Seismic, Wind & Blast product certification. We are a full-service product certification agency executing project specific and product line approvals for a range of code requirements. The TRU Compliance team has been providing product certification services since 2008 and recently joined forces with Structural Integrity in May 2017, thus expanding our resources and reach.

News & Views, Volume 43 | Metallurgical Lab: Dissimilar Metal Welds (DMW) in Boiler Tubing

October 5, 2017/in Fossil Power, Materials Laboratory, News and Views, Tony Studer/by Structural Integrity

By: Tony Studer

The need for confirmation: A Case Study

As plants age, the need for inspection for service related damage to ensure unit reliability increases. There are several approaches that plants can take to reduce the risk of premature failures and proactively manage their DMWs. First is metallurgical sampling. Based on temperature profiles across the boiler, operating conditions, and operating history, DMWs can be selected for laboratory analysis. This will provide some insight into possible damage accumulation; however, the better approach, if damage is suspected, is to perform an ultrasonic inspection of the DMWs. This allows inspection of all the DMWs, and only requires access and surface preparation. If indications are detected, then tube sampling should be performed. It is critical to perform a metallurgical analysis of several of the DMWs suspected of containing service damage to confirm that the indications are service related and to help establish the extent of the damage compared to ultrasonic testing results. Typical DMW damage is described in the Featured Damage Mechanism article. The importance of the metallurgical analysis is demonstrated in the three following case studies.

News & Views, Volume 43 | Metallurgical Lab Featured Damage Mechanism: Failure of Dissimilar Metal Welds (DMW) in Steam-Cooled Boiler Tubes

October 5, 2017/in Fossil Power, Materials Laboratory, News and Views, Wendy Weiss/by Structural Integrity

By: Wendy Weiss

Large utility-type steam generators inevitably contain a large number of pressure part welds that join components fabricated from different alloys.

Background
The welds made between austenitic stainless steel tubing and the lower-alloyed ferritic grades of tubing (T11, T22) deserve special mention because of the early failures that developed in some of these dissimilar metal welds (DMWs) soon after their introduction in superheater and reheater assemblies. Prior to the mid-1970s, many DMWs were fabricated either as standard fusion welds using an austenitic stainless filler metal, such as TP308, or as induction pressure welds, in which the tubes were fused directly to each other without the addition of filler metal. Some of these welds failed after less than 40,000 hours of operation, with the earliest failures being associated with DMWs that operated “hot” in units that cycled heavily and were subjected to bending stresses during operation.

After the mid-1970s, and in response to extensive research carried out by EPRI and other organizations, an increasing number of DMWs in superheater and reheater tubes were fabricated as fusion welds using nickel-based filler metals, such as the INCO A, INCO 82, INCO 182, etc.

News & Views, Volume 43 | Delivering the Nuclear Promise: 10 CFR 50.69 Alternative Treatments for Low Safety-Significant Components

October 5, 2017/in News and Views, Nuclear Asset Integrity, Nuclear Energy, Terry Herrmann/by Structural Integrity

By: Terry Herrmann

News & View, Volume 43 | Delivering the Nuclear Promise- 10 CFR 50.69 Alternative Treatments for Low Safety-Significant Components As all of us who work with nuclear energy know the US nuclear industry is engaged in a multi-year effort to generate power more efficiently, economically and safely. A key goal includes a significant reduction in operating expenses. This initiative is termed “Delivering the Nuclear Promise” (DNP) and is supported by nuclear utilities, vendors such as Structural Integrity, the Nuclear Energy Institute (NEI), Institute of Nuclear Power Operations (INPO), and the Electric Power Research Institute (EPRI).

10CFR50.69’ Risk Informed Engineering Programs (RIEP) is a regulation that enhances safety and provides the potential for large cost savings. This regulation allows plant owners to place systems, structures and components (SSCs) into one of the four risk-informed safety class (RISC) categories as indicated in the graphic to the right.

Industry experience to date suggests that 75 percent of safety-related SSCs can be categorized as RISC-3, low safety-significant (LSS), based on low risk. This is important because (a) it provides a focus on safety significance and (b) RISC-3 SSCs are exempted from “special treatment” requirements imposed by 10CFR50 Appendix B and other regulatory requirements (shown in the boxes at the bottom of page).