Utilizing acoustic emission testing to detect high-temperature hydrogen attack (HTHA) in Cr-Mo reformer reactors and piping during thermal gradients

摘要

Acoustic emission testing (AET) is a powerful non-destructive testing technique that can be used to detect and locate several types of damage mechanisms. High-temperature hydrogen attack (HTHA) is a concern in the oil refining industry because many old vintage C-Mo and Cr-Mo steels remain in operation well past their design lives. There are several documents providing refinery owners and users with guidance on operating high-temperature reactors in hydrogen environments. Nelson curves (API 971) also help determine the likelihood of damage. For this inspection technique to succeed, HTHA damage must be stressed to levels beyond those normally seen during steady-state operating conditions. Thermal gradients during the unit's cool-down offer such an opportunity because they are produced by a relatively rapid temperature reduction that induces considerable thermal stresses. These can cause HTHA (micro-fissures) to propagate, and therefore be detectable by AET. This paper discusses applications of the AET technique and provides an example of this type of inspection.