PREVENTING METHOD FOR STRESS CORROSION CRACKING OF VESSEL THROUGH-PIPE

摘要

PURPOSE:To prevent the stress corrosion cracking of a vessel through-pipe by bringing a pipe wall part in the vicinity of a weld zone of the vessel through-pipe to pipe expansion, generating a compression residual stress and thereafter forming a corrosion resistance coating layer on the inside surface of the pipe of the pipe expansion part. CONSTITUTION:In a vessel through-pipe 2 provided on a reactor pressure vessel, etc., a pipe wall part in an adjacent position of a weld zone 3 between the vessel and the vessel through-pipe 2 is expanded, and a stress exceeding a yield point is generated. A range B of this expanded part is set to a distance exceeding a toe part of the weld zone 3 by prescribed length in accordance with the inside diameter of the pipe and thickness of the pipe wall. Also, the pipe expanding is executed by expanding the pipe wall in the radial outside direction by a roll method, etc. Thereafter, on the inside surface of the vessel through-pipe 2 of the pipe expanding range B, a corrosion resistance coating layer 4 of Cr, Ti, etc., is formed. In such a way, a compression residual stress is generated in the vicinity of the weld zone 3 of the vessel through-pipe 2, and also, a contact with a corrosion fluid is obstructed, stress corrosion cracking is prevented, and also, even if a defective part is generated, its progress is suppressed.