Integrity Assessment of Aged Gas Transmission Pipeline Affected by Tropical Cyclone.
Proceedings Publication Date
Omar Al Ghamari
Omar Al Ghamari, Madjid Afshari
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OQ Gas Networks (OQGN) is the exclusive operator of Oman’s natural gas transportation network that supply natural gas as fuel and feedstock to customers. One of OQGN pipelines, is a 16” pipeline that is crossing the country to deliver gas to some customers including an industrial state in Oman’s north region. The pipeline was commissioned in 1981, with a total length more than 200 Km. Throughout the years, the pipeline has been affected by external soil corrosion which resulted in a deration from original designed MAOP. As there are some customers along the pipeline route, deration cause change in the pipeline original flow direction (Reverse Flow).

In October 2021, a tropical cyclone (Shaheen) made a landfall in the north coast of Oman (where the subject pipeline is crossing). The cyclone was categorized as Category-1 and has caused a major floods and devastation at the north of Oman. Following the passage of the cyclone, right of way (ROW) inspection conducted which revealed a total of 17 exposed locations including around 50 m exposed location which has been buckled.

After detailed assessment, it was decided to perform repair by section replacement on buckled section. Also perform In Line Inspection (ILI) on pipeline after repair with special geometry tool to find if pipeline moved from its original location and if there are local buckling or mechanically damaged sites which are not exposed, hence not detected by ROW inspection.

Section replacement performed successfully; however, it was challenges for performing ILI in reverse direction as pig traps supposed to be used in different purpose than what designed for e.g. using pig receiver as launcher.

Despite all challenges, ILI completed successfully with 5 runs including special geometry, MFL-A and MFL-C. The assessment performed based on findings from ILI campaign and pipeline repair plan developed.

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