When Should the Rules for Severe Cyclic Conditions (Service) in ASME B31.3 Be Used?

This posting (November 2019) is an update to an October 2013 post which reflects changes to the ASME B31.3 Code relative to severe cyclic service that have occurred since the original post. There has been a fair amount of confusion as to when the rules for severe cyclic conditions in ASME B31.3 should be used, […]

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12 Checks When Qualifying Piping Systems in Nuclear Applications

The analysis and qualification of piping systems in nuclear power plants involves more than meeting Code stress limits. Generally, a piping system is qualified if the following criteria have been met. These various qualification criteria are typically specified in the plant FSAR, the plant design procedures, or the ASME Code. Pressure design in accordance with […]

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Evolution of Pipe Stress Equations in the ASME Nuclear Codes (and where we are today)

The Pre-1955 Era Until 1955, the ASME Boiler and Pressure Vessel Codes, and the ASME B31 Pressure Piping code provided rules of good design practice with quantitative criteria for pressure design.  For example, quoting from ASME VIII Rules for the Construction of Unfired Pressure Vessels Section VIII A. S. M. E. Boiler Construction Code, 1927: […]

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Capacity Reduction of a Compression Member with an Initial Deformation

A recent review of equipment installed in a power plant found a piping strut that was visibly bent. Would the bend in the strut reduce its load bearing capacity as a compression member? The answer is YES!  The load bearing capacity of a bent strut against buckling is reduced. The reduction in buckling capacity is […]

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Evaluation of Corroded Pipe in Accordance with ASME B&PV Code Section XI – A Comparison of the Three Code Cases

The evaluation of wall thinning corrosion in steel pipes is addressed in three ASME XI code cases: N-513, N-597, and N-806. I have no ambition here other than to summarize in a table the differences between these three code cases. A brief commentary follows the table. The brief commentary… Line A – While these are […]

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Environmentally-Assisted Fatigue (EAF) in Nuclear Power Plants

Before we tackle environmentally-assisted fatigue (EAF), what is fatigue? In ASME Boiler & Pressure Vessel Section III Division 1, Subsection NB (in short, ASME III NB) fatigue refers to the damage caused by systems and components as a result of cyclic loads. The qualification of the primary coolant system of light water reactors (ASME III […]

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Reduced Toughness Properties of Some Modern Carbon Steels Create Brittle Fracture Risk

Changes in steelmaking practice are reported to be causing some carbon steel piping components that are assumed by ASME Codes to behave in a ductile manner at ambient temperatures, to behave instead in a brittle manner.  Barry Messer from Fluor made a presentation on this subject at the Spring 2016 meeting of the ASME B31.3, […]

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An Integrated Approach to Limit the Effects of Water Hammer on Piping Systems

This article describes an integrated study of thermal-hydraulic and structural loading of bounding piping systems, to establish an operating envelope, screening criteria, and rules of good design practice to protect piping systems from damage caused by valve closure water hammer.  Introduction In many cases of operation or flushing of piping system, it is necessary to […]

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State Approval of Used or Relocated Pressure Vessels

Achieving “State Special” designation for a pressure vessel can require a fair amount of effort in documentation development.   This process is warranted – for example – when a company wants to move a pressure vessel from one facility for operation in a facility located in another state, or when they purchase a used vessel located […]

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