What has been your experience with thread high-pressure steam piping? I have been asked to consider using temporary threaded steam piping for 300 psi steam at about 500 deg. F. The piping is 2", extra strong, carbon steel, A106. There would be no plans to backweld the threads. I am concern about the danger of the threads leaking at such high temperature and pressure. The pipes will be used to steam out equipment and it may be used on several jobs. On permanent installations, screwed steam piping is not permitted.