WRC 585 The Alpha-Omega HTHA Model and the Time-Dependent Prager Curves

Bulletin / Circular by Welding Research Council, Inc., 2021

Full Description

High Temperature Hydrogen Attack (HTHA) has plagued the oil and gas industry for decades, causing many equipment failures and, in some cases, loss of life. The so-called Nelson Curves that currently appear in API RP 941 were first developed in 1949 as a simple means of avoiding HTHA. These material-specific curves represent limiting combinations of temperature and hydrogen partial pressure for acceptable operation; operating below these curves is generally regarded as acceptable (not susceptible to HTHA), while operating above is not. They were derived solely from industrial experience (reported failures).