Rationalization of ASME Section III Piping Seismic Rules

In 1994, a new piping seismic rule of ASME Section III which allowable stress level was rationalized based on the static and dynamic piping test results. Since then, ASME and NRC have had many meetings and discussions toward endorsement. During this period additional analyses and evaluations have been carried out to resolve NRC's concerns and the rule has been improved. The last and most important technical issue has been dynamic strain aging in carbon steel piping. Recently, NRC has acknowledged that dynamic strain aging at the strain rate during earthquake and at the service temperature is negligible and ASME rule is acceptable. It is very important to know the background, technical basis and meaning of the rule to apply the ASME seismic piping rule to the actual nuclear piping and to improve the rule in future. It is a good time to summarize the rule-making process and current status of the rule, because the authors have always played a main role in this revision activity as ASME committee members.