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

Procedia Engineering. Volume 10, 2011, Pages 3552-3560

11th International Conference on the Mechanical Behavior of Materials (ICM11)

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

Claudio Allevato

Stress Engineering Services, Inc., 13800 Westfiar East Dr., Houston, Texas, 77041, USA

Abstract

Acoustic emission testing (AET), a powerful non-destructive testing technique, can be used to detect and locate several types of damage mechanisms, including high-temperature hydrogen attack (HTHA),  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. A number of documents provide refinery owners and users with guidance on operating high-temperature reactors in hydrogen environments. Nelson curves also help determine the likelihood of damage. For the inspection technique to work, 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.

The paper discusses applications of the AET technique and provides an example of this type of inspection.

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