News & View, Volume 46 | Identifying Failure Mechanisms of Typical I-Section Floodwalls

News & Views, Volume 46 | Identifying Failure Mechanisms of Typical I-Section Floodwalls

By: Eric Kjolsing and Dan Parker

News & View, Volume 46 | Identifying Failure Mechanisms of Typical I-Section FloodwallsIn 2018, Structural Integrity Associates, Inc. (SI) supported the United States Army Corp of Engineers (USACE) in the structural assessment of the concrete-to-steel connection in typical I-Section flood walls. A representative flood wall section is shown in Figure 1. This effort was part of a broader scope of work in which the USACE is revising their guidance for the design of flood and retaining walls, EM 1110-2-6066.  The purpose of the structural assessment was to better understand the mechanics of load transfer from the reinforced concrete section to the embedded sheet pile. Three-dimensional finite element models of the connection were developed employing non-linear constitutive properties for the concrete, structural steel and reinforcement to achieve this goal.  A total of nine different I-Wall configurations with varying wall geometry, sheet pile embedment depth, and connection details were analyzed.  Hydrostatic load was applied incrementally to simulate the actual load distribution due to a rising water level. 

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News & View, Volume 46 | Metallurgical Lab Case Study- Cracking of Grade 23 Steel Furnace Wall Tubes

News & Views, Volume 46 | Metallurgical Lab Case Study: Cracking of Grade 23 Steel Furnace Wall Tubes

By: Terry Totemeier

News & View, Volume 46 | Metallurgical Lab Case Study- Cracking of Grade 23 Steel Furnace Wall TubesGrade 23 is a creep strength enhanced ferritic (CSEF) steel that was designed to offer similar creep strength to Grade 91 but with lower Cr content and, in the original concept, fabrication without pre- and post-weld heat treatment making the material attractive for the furnace wall tubes of ultra-supercritical coal plants where T12 has insufficient strength and T91 would be too complex to fabricate. Experience gained with T23 has shown that pre-heat is necessary and that post-weld heat treatment should also be performed when the material is employed in “high restraint” applications such as furnace wall tubes. Like other CSEF steels, T23 is very sensitive to heat treatment, and care must be taken to ensure that hard, brittle microstructures do not enter service – particularly in high restraint applications such as furnace wall tubes.

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News & View, Volume 46 | TRU Compliance Achieves Accreditation as a Product Certification Body

News & Views, Volume 46 | TRU Compliance Achieves Accreditation as a Product Certification Body

By: Andy Coughlin

News & View, Volume 46 | TRU Compliance Achieves Accreditation as a Product Certification BodyTRU Compliance, a division of Structural Integrity Associates, announced in March the achievement of accreditation from the International Accreditation Service (IAS) as a product certification body for seismic, wind, and blast/physical security performance of nonstructural components. According to the International Accreditation Service, TRU Compliance is the second company to be certified for Seismic performance of non-structural components and the first company to be certified for Wind and Blast/Physical Security performance.

“This is a significant milestone for Structural Integrity and our certification agency, TRU Compliance,” Chris Larsen, Vice President of Critical Structures at Structural Integrity comments. “The accreditation further validates our robust program as well as our comprehensive approach, which not only meets the stringent guidelines of the ISO standards but offers our customers a full scope solution for product certification”.

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News & View, Volume 46 | Metallurgical Lab Featured Damage Mechanism- Waterwall Fireside Corrosion (WFSC) in Conventional Boilers

News & Views, Volume 46 | Metallurgical Lab Featured Damage Mechanism: Waterwall Fireside Corrosion (WFSC) in Conventional Boilers

By: Wendy Weiss

News & View, Volume 46 | Metallurgical Lab Featured Damage Mechanism- Waterwall Fireside Corrosion (WFSC) in Conventional BoilersIndustry experience shows that waterwall tubing in conventional boilers can be susceptible to fireside corrosion, depending on fuel type, firing practice, etc. In boilers where fireside corrosion has been identified as a maintenance issue, wastage rates of 5 to 25 mils/year are not uncommon. Since the mid 1990s, the installation of low NOx burner systems designed to lower NOx emissions has significantly increased the wastage rates in some boilers. Operators of subcritical boilers have reported wastage rates as high as 30 mils/year, while those operating supercritical boilers have reported rates exceeding 100 mils/year in the worst cases. These higher damage rates have resulted in an increase in tube failures, and operators have struggled to accurately define the extent of the damage and install the appropriate mitigating technologies.

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News & View, Volume 46 | Delivering Value- Modernization of Plant Automation Controls

News & Views, Volume 46 | Delivering Value: Modernization of Plant Automation Controls

By: Gerry Davina

News & View, Volume 46 | Delivering Value- Modernization of Plant Automation Controls

The modernization of plant automation controls represents a step change in performance that optimizes Operations and Maintenance resources, shifting their focus to performance maintenance and plant monitoring and away from inefficient corrective maintenance and troubleshooting.

According to the U.S. Energy Information Administration, the average age of the U.S.-based nuclear power plant is approximately 38 years old. Three of the “youngest” plants (Watts Bar, Nine Mile Point 2 and River Bend) all began construction in the mid-1970’s with their designs approved years earlier. In terms of industrial control systems, this means that most, if not all, of the plants in the U.S. nuclear fleet, continue to operate with 1970s in automation equipment and technology. Although it can be argued that the equipment and technology have proven to stand the test of time, the reality of the digital age, with low cost and high-powered processors, is that relay-based control systems are long-obsolete and no longer practical for any automation system that requires more than a handful of relays and switches. In an industry that has publicly advocated a commitment to improved reliability and efficiency, ironically, the most evident impact for any plant with the continued use of 40-year-old automation equipment and technology is poor system reliability and inefficiency burdening both Operations and Maintenance resources.

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News & View, Volume 46 | Assessing Prestress Losses in a Nuclear Containment Structure for License Renewal

News & Views, Volume 46 | Assessing Prestress Losses in a Nuclear Containment Structure for License Renewal

By: Eric Kjolsing

News & View, Volume 46 | Assessing Prestress Losses in a Nuclear Containment Structure for License RenewalNuclear power plants around the world are approaching the end of their original 40-year design life.  Efforts are underway to extend the operating license for these plants to 60 years or beyond.  As part of the license extension, it must be demonstrated that the reactor containment building remains able to safely perform its intended functions for the extended duration of operation.  Many of these containment buildings utilize a post-tensioned concrete design where the tendons are grouted after tensioning.  Since these grouted tendons cannot be re-tensioned, an assessment for the loss in prestress beyond the original design life must be performed.

This article describes a methodology to assess the structural performance of a containment structure over time as a function of confidence in the tendon losses and is split into three parts:

  1. A description of the methodology
  2. A representative probabilistic assessment
  3. Representative analysis results

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News & View, Volume 46 | Strategies, Projects and Technologies to Help Improve NDE Reliability in the Pipeline Industry

News & Views, Volume 46 | Strategies, Projects and Technologies to Help Improve NDE Reliability in the Pipeline Industry

By: Scott Riccardella, Jason Van Velsor, and Roger Royer

News & View, Volume 46 | Strategies, Projects and Technologies to Help Improve NDE Reliability in the Pipeline Industry

Pipeline operators face a multitude of threats, including service, environmental, or operational induced degradation to pipelines and related facilities. Non-Destructive Examination (NDE) is often used to characterize the nature and extent of this degradation. Thus, there is a critical need for reliable NDE as pipeline operators rely extensively on NDE as the basis for validating In-Line Inspection (ILI) results, determining fitness for service, and making repair and other operational decisions. Erroneous or inaccurate characterization of these defects can lead to unexpected leaks or failures, unnecessary and costly repairs, the establishment of an incorrect remaining life or re-assessment interval, and inaccurate (in)validation of ILI results.

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News & View, Volume 46 | Acoustic and Blowdown Load Calculations for Reactor Internals

News & Views, Volume 46 | Acoustic and Blowdown Load Calculations for Reactor Internals

By: Matthew Walter

News & View, Volume 46 | Acoustic and Blowdown Load Calculations for Reactor InternalsAs part of the general design criteria for nuclear power plants, the primary structures and systems of the plant must be designed to handle postulated accident events, including the dynamic effects of postulated pipe ruptures. For a Boiling Water Reactor, analyzed events include various accident conditions in the recirculation piping, including a Loss of Coolant Accident (LOCA). One postulated LOCA event is assumed to be an instantaneous double-ended guillotine break of the recirculation line. This event causes several loads to be imparted on the reactor vessel, attached piping, and reactor internal components. [Some loads such as jet impingement, annulus pressurization, and pipe whip impart loads on the outside of the reactor vessel and the attached piping.][ Other loads, including flow-induced drag and acoustic loads, transmit loads inside the vessel on critical components such as jet pumps, core shroud, and the shroud support structure.] Figure 1 shows the pipe and resulting loads.

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News & View, Volume 46 | Adding Value Through Test Informed Modeling- Hydro Structures

News & Views, Volume 46 | Adding Value Through Test Informed Modeling: Hydro Structures

By: Eric Kjolsing and Dan Parker

News & View, Volume 46 | Adding Value Through Test Informed Modeling- Hydro StructuresIn 2018, Structural Integrity Associates (SI) supported a utility in the structural assessment of a submerged concrete intake tower.  The tower is nearly a century old and was investigated as part of the utility’s periodic maintenance program. 

The assessment required the generation of an analysis model that accounted for both the structure and the surrounding water.  When accounting for fluid effects, a typical analysis approach is to develop a fluid-structure interaction (FSI) model that explicitly accounts for the interaction between the surrounding water and concrete tower.  However, this modeling approach is expensive both in terms of (a) cost, due to the increased effort needed in generating the model and (b) schedule, due to the increased analysis run time.  In lieu of developing an FSI model, SI implemented an alternative numerical approach to model the effects of the water and justified the approach through physical testing of the in-situ structure.

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News & View, Volume 46 | The Newest Phased Array Ultrasonic Technique- Full Matrix Capture

News & Views, Volume 46 | The Newest Phased Array Ultrasonic Technique: Full Matrix Capture

By: Jeff Milligan, Steve Gressler, and Allen PorterNews & View, Volume 46 | The Newest Phased Array Ultrasonic Technique- Full Matrix Capture

Full Matrix Capture (FMC) and Total Focusing Method (TFM) have evolved over the past few years into NDE buzz words that warrant explanation and context for their proper and successful application.  Structural Integrity (SI) is well vested and engaged in FMC and actively exploring the use of this technology where it enhances ultrasonic sensitivity and characterization to bring added value to our clients.  An explanation of these technologies and what they mean to the future of ultrasonic inspection follows.

Phased Array Ultrasonic Testing (PAUT) has evolved significantly over the last 20+ years, with improvements and innovations in sensor design, signal processing, and data interpretation; however, the method by which PAUT is applied has remained relatively unchanged: Excite an array of transducer elements with predetermined time delays, called focal laws, and receive resulting reflections with the array of transducer elements,

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