scope:

The published positions of the Technical Committee have been developed with the aim of providing a balance between design for thermal expansion effects which occur frequently during normal operation and design for dynamic and seismic events which occur as a result of abnormal plant operation, or are postulated events. Sufficient review has been performed to demonstrate that use of these positions will reduce the restraints required to provide protection against a postulated seismic event thereby allowing more flexible piping design. In addition, studies have been performed which demonstrate that sufficient margin exists when the published positions are used for piping design. The studies compare the results of time-history seismic analyses against seismic analyses using the Technical Committee positions and in all cases show a margin (technical committee positiodtime-history) on moment (stress) greater than 1.0 with a mean of 3.0.