EVALUATION OF CRACKING IN THE 241-AZ TANK FARM VENTILATION LINE AT THE HANFORD SITE

摘要

In the period from April to October of 1988, a series of welding operations on the outside of the AZ Tank Farm ventilation line piping at the Hanford Site produced unexpected and repeated cracking of the austenitic stainless steel base metal and of a seam weld in the pipe. The ventilation line is fabricated from type 304L stainless steel pipe of 24-inch (60.96 cm) diameter and 0.25-inch (0.64 cm) wall thickness. The pipe was wrapped in polyethylene bubble wrap and buried approximately 12 feet (3.66 m) below grade. Except for the time period between 1980 and 1987, impressed current cathodic protection has been applied to the pipe since its installation in 1974. The paper describes the history of the cracking of the pipe, the probable cracking mechanisms, and the recommended future action for repair/replacement of the pipe.