Burns, Jonathan; MISTRAS GROUP LTD; United Kingdom

Burns, J.M.; Mistras Group Ltd.; United Kingdom
Tsimogiannis, A.; Mistras Group Ltd.; United Kingdom

ID: ECNDT-0565-2018
Session: Oil & Gas 1
Room: H2
Date: 2018-06-11
Time: 13:30 - 13:50

The use of Acoustic Emission (AE) for medium to long term continuous monitoring of critical assets in the oil and gas sector continues to become more widespread; the technology is generally deployed to provide assurances for the safe and reliable operation of process critical equipment as required by operators and regulators. AE is an effective tool for the detection of environmental assisted cracking (EAC), particularly where there is a high potential risk of wet H2S damage mechanisms, e.g. sulfide stress cracking (SSC), hydrogen induced cracking (HIC) and stress oriented hydrogen induced cracking (SOHIC).

Several resources are widely available to support AE monitoring, including API document 581, which refers to the use of AE as a highly effective Non-Intrusive Inspection (NII) approach for the detection of SSC when used in conjunction with shear wave as a follow-up tool. API recommended practise 571 also recognises that AE is effective in monitoring crack growth for wet H2S damage mechanisms.

This paper details case study references for process separator vessels operating in sour service where AE was employed for the detection of new defects or to continuously and closely monitor existing defects until maintenance. The vessels were monitored over a medium or long-term period using permanently installed acoustic emission equipment integrated to the facilities’ DCS/SCADA systems. Field implementation of the technology followed a series of validation studies where the properties of AE signals generated from SSC in a high-strength steel were characterised. Details of the validation studies and continuous monitoring projects are presented herein.