Outer Surface Irradiated Laser Stress Improvement Process (L-SIP) was developed as a counter measure for stress corrosion cracking at the tube and nozzle stub weld in the nuclear power plant and the thermal power plant. L-SIP is a technique for improving the inside tensile residual stress to the compressive stress. Rapidly heating by the laser beam irradiation to outer surface causes the temperature difference between outer surface and inner surface, and it can reduce the residual stress. In this paper, the developed system, the verification test results and the practical use situation are described.
