Suspect HTHA Damage Based on Time-Based Curves

Abstract High Temperature Hydrogen Attack (HTHA) evaluation has evolved over the years, introducing new equipment types that were not initially intended to be inspected. However, applying high-sensitivity inspection techniques to such equipment can reveal fabrication defects that are difficult to distinguish from early-stage HTHA. This paper reviews the susceptibility evaluation of a piece of equipment operating below the non-PWHT Nelson curve. The evaluation is based on time-based curves and highlights the potential pitfalls operators may encounter when following best-practice inspection techniques