Application of the Fracture Mechanics-Based Methodology to Determine Minimum Pressurization Temperatures in Accordance with WRC Bulletin 562

Preventing brittle fracture is an essential part of establishing life-cycle management strategies for fixed pressure equipment. Using fracture mechanics principles to develop permissible minimum pressurization temperature (MPT) envelopes for components is one way to mitigate the potential for unstable flaw growth. In the refining industry, heavy-walled, low-alloy hydroprocessing reactors are designed to operate at elevated temperatures and high hydrogen partial pressures. Components that operate in high-pressure hydrogen environments require special treatment and necessitate guidance that falls outside the bounds of current pressure vessel construction codes. This operating environment results in two factors that affect the MPT envelope: long-term temper embrittlement and hydrogen embrittlement.