Abstract
Low alloy steels containing chromium and molybdenum (CrMo steels) are widely used in pressure equipment in the petrochemical industry. However, if their manufacturing and production welding are not properly controlled, or if they are operating beyond their design conditions, these steels can exhibit brittle behavior at higher than expected temperatures. There are recommendations and requirements in the industry for controlling key parameters during welding. Before they are performed, production weld procedures must be reviewed against the test results from mock-ups to meet certain requirements such as impact toughness, X-bar, and J-factor. However, there is not much industry guidance for assuring the production welding occurs as per the reviewed parameters. This paper discusses three case histories of CrMo alloyed pressure equipment. One of the case histories is for a reactor, and the second case history is for a heat exchanger. The final case history discussed is for piping material. Details of manufacturing, production welding, and testing are discussed in the case histories. For some of the case histories, this includes finding lower impact toughness during production test welding than was expected based on the procedure qualification record. Finally, the paper discusses the importance of additional steps that could be added to the inspection test plan to improve the monitoring of production welding.
