Defect Remedy Procedures Using Cold Method on Superheater Header (SA335 P11)

This research deals with crack remedy using the cold method on a 12-inch-diameter vintage superheater header (SA335 P11) with 33.32 mm thickness where the crack is found around the borehole of the tube sheets. For many years, using the hot method for crack remedies on in-service superheaters was time-consuming and expensive. It has become a significant challenge for industrial practitioners due to the lack of established procedures for a crack remedy for in-service superheaters. This study aims to publish an industrial solution based on a novel approach of the cold method remedy to prevent crack propagation during repair, which can also avoid rework and save labour and time. Implementing defect cold method remedy procedures saves 15% on total costs. Cooled compressed air is the main ingredient in this method, which has never been used before, and one of the factors in stopping crack propagation. The cold method remedy started with pre-cleaning, initial visual inspection (VI), penetrant testing (PT), in-situ metallography microstructure evaluation, mechanical sub-surface removal using burr grinding, build-up of the sub-surface using TIG welding, and finally, defect-free verification using penetrant testing (PT) and ultrasonic testing (UT). These activities are required to reduce the effort and time required for SA335 P11 crack repair. Apart from those activities, a cost comparison between the cold method and the hot method is also calculated. As concluded from the research, it is found that the cold method remedy successfully prevents crack propagation on the in-service superheater as well as is saving time and cost.