Life Extension of Hydrocarbon Equipment in Sour Environment

Abstract

Reliability of equipment is indispensable for the uninterrupted operation of any oil & gas producing facility. Over a period of time, some oil wells producing sour crude were also added to the incoming feed of Gathering centres, which were originally designed for processing sweet crude. Most of the facilities were designed and installed prior to the publication of NACE MR 0175 and NACE TM 0284. As these facilities are still in operation under sour condition, it is prudent to take necessary measures in time for continuing safe operation of these facilities. In this paper, the authors share their experience in initial detection & online monitoring of service-induced damages to the equipments due to sour service using NDT techniques like Wet Fluorescent Magnetic Particle Inspection, manual ultrasonic testing and time of flight diffraction & Phased Array. The experience gathered during internal coating of the vessels has also been described. Several items of equipment continued in operation to maintain production even after the detection of Hydrogen induced cracking. Periodic monitoring and critical analysis of inspection data provided confidence to continue operation of equipment. This enabled the operating company to extract maximum life of the equipment without compromising on safety. This Paper focuses on two items of equipment, HP Gas Scrubber from Oil/Gas separation plant and HP Gas Discharge Cooler from CRU. Fitness for Service (FFS) evaluations were carried out for HP Scrubber and the Channel head component of HP Gas Discharge cooler. The analysis was based upon the latest UT scan results and guidelines prescribed in API 579-1/ASME FFS-1. These items of equipment were found not fit for further service. In the interim period, the company procured new scrubber and channel head of the cooler for replacement thus minimizing the shutdown period.