PROBING FOR HTHA Daly Souissi, Olympus, Canada, explores a new strategy for HTHA inspection.
T
he high-temperature hydrogen attack (HTHA) damage mechanism is a critical concern in ammonia plants, refineries and other petrochemical facilities. The operating conditions (e.g. temperature, hydrogen partial pressure [HPP], stress, in-service duration, etc.) of processing equipment in these types of facilities increase the risk of HTHA occurring. Monitoring the integrity of the equipment components for HTHA is necessary to avoid failures
and accidents; however, inspecting for such damage is challenging and requires a specific strategy using a range of techniques in accordance with API RP 941. In this article, the focus will be primarily on HTHA inspection using advanced ultrasonic testing (UT) techniques, including focused phased array UT (PAUT), full matrix capture (FMC)/total focusing method (TFM) and Dual Linear ArrayTM (DLA). A specific case study will be discussed.
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