Study of Weld Joints Qualification as Per ASME Code: SCRF Cavity, A Case Study: Qualification of Niobium Weld Joints for SCRF Cavity

Abstract

Efforts are on-going towards development of Superconducting RF cavity manufacturing technology at RRCAT. The aim of fabrication of prototype cavity is to gain experience in this highly specialized technology. The SCRF cavities are made of high purity niobium and joined by Electron beam welding.These welded joints are required to qualify as per the code, Section IX which covers welding and brazing qualifications. Niobium being a non-code material as per ASME Section II, Part D, it requires special condition to qualify as per Section VIII, U-2(g). This paper involves a case study being carried out for qualification of some of niobium weld joints for SCRF Cavity. The paper aims to describe various requirements for weld joint design, preparation of related documents like WPS, PQR, preparation of test coupon and welding. The paper will also describe initial testing done and test results.