Dear Sir: We cannot make material recommendations in a discussion forum, based on the limited information that is typically available. However, a review of the chemical and mechanical properties for A-312 347H and A-376 347H material reveals no differences. A-376 is a seamless product spec only while A-312 allows both seamless and welded pipe. Therefore, we would expect pipe from the two specs to behave similarly, except for the seamless vs. welded issue. Hope this helps! David Hendrix The Hendrix Group Inc.