Half-bead (temper) repair welding for heavy-section steel technology program vessels
The ''half-bead (temper) welding technique'' performed to Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code guidelines was used successfully on cavities placed in three thick-walled pressure vessel models to simulate repair welding of operational nuclear reactor vessels. One of the models served as a qualification-procedure test specimen, as required by the Code, and was subsequently utilized for detailed metallurgical examinations. The temper-, or half-bead, technique, in theory, is structured such that each weld pass is applied in a manner which results in tempering the preceding weld pass. Thus, brittle transformation products created during welding will be rendered ductile. Conventional postweld thermal stress relief is not required. The repair welding was performed on 152.4-mm-thick low-alloy steel vessel material (ASME SA-533, grade B, class 1) in the vertical position, using 2.4-mm-diam type 8018-C3 electrodes for the first layer and 3.2-mm-diam electrodes of the same type for subsequent passes and for completing the weld. After welding, a low-temperature temper treatment, or postweld heat treatment (PHWT), was performed for 4 hr. Routine magnetic-particle inspections were conducted for each of the first three weld passes and thereafter on alternate passes. Final nondestructive repair inspections were made a minimum of 48 hr after the vessels had cooled to ambient temperature. Magnetic-particle surface inspections and ultrasonic inspections of the repairs revealed no indications of any delayed cracking. A second ultrasonic inspection of one of the vessel repairs by ORNL approximately 12 weeks after postrepair welding also revealed no indications of delayed cracking. Final ultrasonic and radiographic test results were acceptable for all repair welds.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 6698825
- Report Number(s):
- NUREG/CR-0113; ORNL/NUREG/TM-177; TRN: 78-016157
- Resource Relation:
- Other Information: Portions of document are illegible
- Country of Publication:
- United States
- Language:
- English
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