WRC Bulletin 601: Fitness-for-Service Assessment of FRP Equipment

June 6, 2023

A new Welding Research Council (WRC) Bulletin by UTComp founder and Chief Technical Officer Geoff Clarkson addresses the gap in inspection standards for in-service fiber-reinforced polymer (FRP) assets.

WRC Bulletin 601 — “Assessment of Existing Fiber Reinforced Polymer Equipment for Structural Damage” provides reliability engineers with a technically valid, quantitative and repeatable process for evaluating fitness-for-service of FRP composite equipment.


Pressure vessels, piping and tankage made from Fiber Reinforced Thermosetting Polymer (FRP) have been in industrial service in chemical plants, refineries and other facilities since the 1950s. Most service conditions will damage the FRP materials used for the equipment. This damage can impact the Fitness-For-Service (𝐹𝐹𝑆) of the equipment. As for most metal alloys, damage experienced by FRP is not always uniform and may be concentrated in localized areas. The situation is compounded because the damage that occurs is not detected using any of the inspections used in construction codes or other existing standards. There are no standardized codes to evaluate 𝐹𝐹𝑆 of in-service equipment made from FRP. In this Bulletin, we describe gaps between construction codes and damage; provide a technical basis for determining the extent of damage that has occurred to these materials; and show how to determine 𝐹𝐹𝑆. A methodology for determining 𝐹𝐹𝑆 will be presented that is independent of construction codes, specific materials, material tensile strength and normal service conditions. It is recommended that a part be added to API 579-1/ASME FFS-1 to incorporate this methodology.

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Cover image of WRC Bulletin 601 Assessment of Existing Fiber Reinforced Polymer Equipment for Structural Damage