Process Development and Parameter Evaluation for Automatic Repairing of Stainless/Carbon Steel Pipes in Nuclear Power Plants

There are three nuclear power plants in operation currently in Taiwan. Various defects have been detected in piping after years' operation. It is necessary to repair or replace the defective pipes to ensure safety of the power plants. Due to the needs to improve weldment quality, plant operation safety, and to shorten exposure of personnel in the radioactive environment, automatic welding techniques for repairing pipes will be developed to establish optimum operation conditions in this program. The first year of this 2-year program will be devoted to the study of the related parameters in automatic gas tungsten arc welding (GTAW). Mechanical testing and optical microscopic / macroscopic observations will be used to evaluate the weld quality. The operation windows of various parameters will be established and used in the subsequent study. Works to be carried out will include: (1) literature review; (2) design of welding experiments; (3) sample machining, welding and data collection; (4) weldment quality evaluation; (5) sensitivity study of parameters; and (6) establishment of guidelines for selecting automatic GTAW pipe-welding parameters. The second year will be used to develop the automatic GTAW pipe-welding system. Similarly, mechanical testing and optical microscopic/macroscopic observations will be used to evaluate the weld quality. The operation windows of various parameters for in situ weld repairing will be established. Works to be carried out will include: (1) study of weld joint preparation; (2) design of full-size welding experiments; (3) sample machining, welding and data collection; (4) weldment quality evaluation; (5) sensitivity study of parameters for repairing full- size pipes; and (6) establishment of the automatic GTAW pipe-welding operation manual.

Project ID:PG8901-0382
External Project ID:892001INER001