Qualification of Induction Heating Stress Improvement for Mitigation of Stress Corrosion Cracking

This paper describes the efforts toward qualification of induction heating stress improvement (IHSI) for mitigation of intergranular stress corrosion cracking (IGSCC) in Boiling Water Reactor (BWR) piping. The IHSI process, which is applied to piping after it is fully erected, produces compressive residual stresses on the pipe inside surface in the vicinity of the weld heat affected zone (HAZ). The creation of these compressive stresses has been confirmed by surface and through-wall strain gage and X-ray diffraction residual stress measurements on 4, 10, and 16-in. dia Schedule 80 welded and IHSI treated pipes. Confirmation of increased resistance to IGSCC due to the IHSI process has been accomplished by full-sized 4-in-dia pipe tests in General Electric’s Pipe Test Laboratory. The pipe test utilized an environment of oxygenated high-purity water at 288°C (550°F). Axial loads were applied which exceeded the material 288°C yield strength.