Abstract
In order to simulate tempered and hydrogen embrittled pressure vessel steel in the laboratory, hydrogen exposure in autoclave equipment and repair welding using shielded-metal arc weld consumable for the large size specimen exceeded 100mm thickness were carried out. Minimum stainless steel overlay thickness that became a standard of the repair time estimation was obtained by investigation of characteristics at the repair welds, such as dilution, hardness and microstructure. In addition, tensile test were carried out using re-hydrogen exposed specimen, and serviceability of recent generation 2. 25Cr-1Mo pressure vessel steel repair welds was confirmed.
