Inspection and treatment for surface cracks of stainless steel surfacing layer in pressurized hydrogen environment

摘要

Stainless steel surfacing layer is widely used for the equipments working in pressurized hydrogen environment such as hydrogenation reactors in order to improve the corrosion resistance. Surface cracking is a basic failure mode of the layer due to the extreme working condition. It is also a quite difficult problem for safety assessment and defect elimination. In this paper, a typical case of surface cracking of the layer in hydrogen environment is analyzed in detail. Inspection methods including non-destructive testing (NDT) for confirming quantity and location of surface cracks are introduced. Surface cracking causes and treatment methods for the defects are also studied. Finally, some suggestions for inspection and treatment of surface cracks of the layer are proposed. Phased array ultrasonic testing is an effective NDT method for confirming the extension of surface cracks. Fitness for service assessment for the cracks of stainless steel surfacing layer is suggested. Defect elimination method is only suggested to be adopted if the cracks extend into the base metal.