Why do Clamped Connections With Metallic Seals Sometimes Leak?

Clamp connections with metallic seals can offer superior joint integrity over traditional flanged connections but caution must be exercised regarding the service conditions, especially when cyclic thermal loading is present. This blog post highlights aspects of a clamp connection analysis performed by Becht Engineering. The client had observed significant loss of bolt preload at several […]

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Grade 91 Steel – How Did We Get Here? Part 1

This blog is the first part of a 3-blog series. To view the rest of the story click HERE for Part 2 and Here for Part 3. Part 1: History Thirty years ago, Grade 91 (9Cr-1Mo-V) steel was hailed as the savior of the power generation industry [1]; now it’s behavior has been described as […]

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Grade 91 Steel – How Did We Get Here? Part 2

Read Part 1 Part 2: Type IV Cracking and Inspectability The current concerns with Grade 91 are fundamentally and firmly rooted in inspectability of Type IV damage; while sensitivity of the material can be managed (see for example [1]), Type IV cracking is perhaps the Achilles heel of Grade 91.  At a high level, the […]

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Grade 91 Steel – How Did We Get Here? Part 3

Read Part 1 or Read Part 2 Part 3: Allowable Stresses While inspectability has been at the center of recent concerns, other issues such as chemistry control, ductility and excessive oxidation have also come under scrutiny.  Perhaps most interesting is that while all of the preceding concerns have been debated, it has also been found […]

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EPRI Publishes “Roadmap to Integrity Evaluation and Repair of Nuclear Plant Piping”

EPRI has just published the report “Roadmap to Integrity Evaluation and Repair of Nuclear Plant Piping” EPRI report number 3002013156, dated December 2018, prepared by Becht Nuclear Services, under EPRI Project Manager T. Eckert. The methods and criteria for the evaluation of degraded and non-conforming conditions in piping systems in nuclear power plants are dispersed […]

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Restoring High Energy Piping System Performance by Reducing Friction

“When You’re Stuck, You’re Stuck” Over years of normal operation – like cycling and wear and tear – High Energy Pipe support friction can increase causing distress in these critical systems. Friction is a common phenomenon which is widely understood and considered in both piping analysis and support design.  Generally, a piping analyst models a […]

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ASME B31.3 – Substantive Changes in the 2018 Edition for Process Piping

In addition to the many clarifications, updated references to codes and standards, updates to basic allowable stresses, and added listed materials, there are several substantive changes to the 2016 Edition of ASME B31.3, Process Piping, which is scheduled to be issued mid-January 2019. These substantive changes are: Owner Added specific permission for the owner to […]

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Basics of Design By Analysis in ASME Section VIII, Division 2

How hard can it be?  I’ve heard from several (unnamed) analysts that because they have access to an FEA program and have successfully applied FEA in other fields, that FEA for pressure vessels should be a snap.  What is it about FEA for pressure vessels that makes it unique? I was recently discussing with another […]

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Reducing Loss of Primary Containment (LOPC’s) in a Refinery

Reducing Loss of Primary Containment (LOPC’s) or commonly referred to as “leaks” in a refinery is a key factor to improve reliability.  Historically, most refiners reduced the high consequence leaks to avoid major incidents; however, lower consequence related leaks were not given high priority.  Today high reliability is required, and reduction of all leaks is […]

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Elastic Follow-up Can Result in Failures in Systems that Comply with Piping Code Rules

The analysis procedures in the Code essentially assume that the strain range in the system can be determined from an elastic analysis. That is, strains are proportional to elastically calculated stresses. The stress range is limited to less than two times the yield stress, in part to achieve this. However, in some systems, strain concentration […]

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