Abstract

This paper discusses high energy piping (HEP) system walkdown requirements and guidelines in compliance with the American Society of Mechanical Engineers (ASME) B31.1 Code. Chapter VII states that the Operating Company shall develop and implement a program requiring documentation of piping support readings and recorded piping system displacements. Guidelines for this program are provided in Nonmandatory Appendix V, para. V-7. The Code also requires that the Operating Company shall evaluate the effects of unexpected piping position changes, significant vibrations, and malfunctioning supports on the piping system’s integrity and safety. These requirements and guidelines have been developed for personnel safety and piping system reliability.

The HEP system should be maintained to behave as expected in the original design analysis unless a field change is justified by qualified personnel. The walkdown program should be an integral part of an asset integrity management program, including observations, documentation, evaluations, corrective actions, and countermeasures.

A thorough HEP system walkdown includes more than documented hanger readings. It should include visual assessments of possible sagging pipe, unusual pipe slopes, building structure damage, lagging/insulation damage, locked spring hangers, piping interferences, damaged spring coils, loose/missing support fasteners, unloaded rigid supports, bent struts, insufficient hydraulic fluid in snubbers, detached Teflon strips on sliding supports, and confirmation that the current supports are consistent with the original design specifications. If accessible, it should be confirmed that there are no gaps in the sliding supports.

This paper illustrates that it is now possible to photographically document spring support position indicator readings from distances up to 30 feet (9.1 meters). Photographic documentation provides higher confidence in the position indicator readings and can resolve many visual documentation discrepancies, such as incorrect support readings, readings from opposite position indicator sides, and parallax issues. If accessible, closer inspections may confirm if a spring support is in fact internally bottomed-out or topped-out.

Nonmandatory Appendix V provides recommended hot walkdown and cold walkdown forms. These forms provide additional space for applicable notes. Example photographs of many piping system anomalies and associated documentation are provided in this paper. ASME B31.1 requires that significant displacement variations from the expected design displacements shall be considered to assess the piping system’s integrity.

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