Optimize Equipment Startup, Shutdown, and Operating Limits

Problem

An owner-operator identified that actual startup and shutdown practices for a high-pressure hydrogen reactor were operating outside the original OEM minimum pressurization temperature (MPT) limits. The true risk of brittle fracture and hydrogen-assisted cracking under these conditions was unclear, particularly given modern understanding of fracture mechanics, material toughness, and hydrogen effects.

Solution

A detailed MPT assessment was performed using modern API 579 and WRC methodologies, incorporating fracture mechanics, material toughness characterization (CVN and chemistry-based methods), residual stress considerations, and hydrogen diffusion modelling. Operating data was benchmarked against newly developed MPT curves, including sensitivity to hydrogen concentration and thermal/pressure transients. Simplified screening methods (WRC 599) were used to quickly bound behavior, with recommendations for more rigorous analysis where required.

Value

Provided a defensible technical basis to evaluate and potentially expand the safe operating envelope beyond legacy OEM limits. Reduced uncertainty around brittle fracture risk during transient operations. Enabled development of updated startup/shutdown procedures aligned with current codes and practices, improving both safety and operational flexibility while avoiding unnecessary conservatism.