Socket weld fittings, commonly manufactured from carbon steel and both austenitic and duplex stainless steels, are used in instrumentation points, vents, and drains. One of the most common failure mechanisms of socket weld assemblies is high cycle fatigue at the fillet welds that connect the socket weld fitting and the pipe. The formation and progression of fatigue cracking is exacerbated by the presence of vibration, the weight of the components and the presence of unsupported connections.
Typical inspection methods such as magnetic particle inspection, dye penetrant inspection, visual inspection, and sometimes digital radiography are claimed, by some, to not have a high probability of detection, especially with regard to cracks that have initiated at the weld root and are not surface breaking. As a result, this project aims to identify the current inspection methods used in service and techniques that have potential for this challenging problem.
The main objective of this project is to develop a recommended practice for the inspection of socket weld fittings. The guidance will be based on the results of a rigorously controlled blind trial programme and group member experience.
Following issuance of the trial report, the decision was made by HOIS members to proceed with the creation of a new guidance document on the inspection of socket weld fittings. The guidance document was completed in early 2026 and is now available to HOIS members.
This project was completed in early 2026.