Studies on the creep behaviour of the structural material 316 L (N) in the low-stress range at 550 and 600

This paper deals with the operating experience of the power plant life assessment system observing the boiler drum only. The scope of the assessment system is the range of a thick wall vessel operating at temperatures below 400°C. The system was initiated by boiler drums with the same material properties having suffered ruptures during pressure test after urgent repairs on other steam generating equipment. The main concern was focused on the high life reduction during the ambient temperature 1.5 * p pressure test, when the actual damage cases occurred. With growing experience the evaluation of fatigue is extended to normal operation, start up and shut of periods. The systems have been enhanced and have successfully reduced the operational fatigue sources. The resulting improvement in material life use has been enhanced 4-5 times over the results from the first year in operation. © 1999 Elsevier Science S.A. All rights reserved.