API TR 941-A

IMPORTANT: The designation/number for this document has changed from TR 941 to TR 941-A. This is to differentiate it from RP 941.

The Technical Basis Document for API RP 941.

Even before the first edition of API Publication 941 "Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants" appeared in 1970, there had been fundamental questions regarding the technical basis for the materials performance curves contained in the document (1-6). Based upon sparse laboratory data combined with plant experience, with only a few exceptions, the curves have done an exceptionally good job at safely directing the refining industry in selecting materials based upon operating temperature, hydrogen partial pressure, and the metallurgy of the equipment being considered.