Becht Engineering Blog

Bringing Order and Logic to the Evaluation Process There is a multitude of documents and reports that describe the damage mechanisms of ASME pressure equipment (vessels, pumps, valves, piping, and tanks, and their supports) in nuclear power plants. Thousands of pages published by EPRI, the NRC, ASME, NACE, research laboratories, utilities, contractors, and others, to read, study, and understand. The plant engineer must understand these thousands of pages of damage mechanisms, first to take the right preventive measures, and second, when the damage occurs despite our best efforts, to correctly diagnose the remaining life of the equipment, i.e. determine its fitness-for-service, its operability. In December 2018, EPRI published “Roadmap to Integrity Evaluation and Repair of Nuclear Plant Piping” EPRI report number 3002013156, to help the plant engineer navigate through the technical and regulatory complexities of damage mechanisms and the methods for the evaluation of remaining life. This is an important step...

Contributing Authors: Eileen Chant, Greg Epremian, Ranjan Nadarajah, Mark Stonehouse  Summarized herein are the substantial changes to API 579-1/ASME FFS-1, Fitness for Service , that were incorporated in the 2016 edition, as reviewed by Becht Fitness for Service experts. API 579-1/ASME FFS-1 is a Standard jointly published by API and ASME.  The purpose of the document is to provide a consensus of methods to quantitatively evaluate commonly observed damage to in-service pressure equipment.  Since it was first issued by API in 2000, this Fitness-For-Service standard has been used worldwide as a means of evaluating whether pressure equipment was fit for continued service, and in many cases, for how long.  This standard has been used to avoid costly and unnecessary unplanned outages, while maintaining safe and reliable equipment.  The Second Edition was released in 2007, followed by the most current release of the document in June of 2016.  In addition to the...

Settlement of a pipe support foundation is usually not a big deal to assess. A local piping flexibility model will reveal if the settled support keeps the pipe bending stresses within the allowable codes and, if the bending stresses are unacceptable, modifying the support and monitor periodically for further settlement is normally a quite manageable task. However, if settlement is occurring site-wide at a large site due to errors in the pre-construction soil surveys, the problem quickly becomes unmanageable. A client recently approached Becht Engineering with a request to develop a screening tool. A tool that inspectors at such a site can easily use in the field to quickly screen pipe circuits subjected to support settlement. The stated objective was to determine which circuits are acceptable without further study based on conservative criteria requiring detailed follow-up, i.e. piping flexibility analysis. This blog supplies an overview of the bases for this tool....

This article outlines the procedure to evaluate the fitness-for-service of corroded buried pipe, and explains what CC N-806 covers … and what it does not cover. What are the Damage Mechanisms in Metallic Buried Pipe? The inspection of a buried metallic pipe, after years of service, can reveal that the pipe has little if any damage, or on the contrary that the pipe has undergone one of four types of damage: Wall thinning caused by ID erosion, or by ID or OD corrosion. This wall loss can be in the form of pitting, local thin areas, or general metal loss. Wall thinning is the damage mechanism addressed in CC N-806. Cracking caused by fatigue, corrosion, or both. It can also happen that construction flaws are discovered that were undetected when the pipe was installed. Cracking is not addressed in CC N-806. Embrittlement, typically in the form of leaching. Embrittlement is not...