Pipeline Integrity Management Under Geohazard Conditions (PIMG)
Chapter 41 Managing Risk: Effective Use of Structural Reliability Assessment (SRA) and Quantitative Risk Assessment (QRA) for Sabah-Sarawak Gas Pipeline (SSGP)
Download citation file:
PETRONAS is operating Sabah-Sarawak Gas Pipeline (SSGP) that traverses hilly and mountainous terrain with significant rain fall in East Malaysia i.e. in state of Sabah & Sarawak. SSGP is an important pipeline asset to PETRONAS flowing around 700-800 MMSFCD of sales gas to PETRONAS LNG complex in Bintulu, Sarawak. The pipeline experienced leak in 2014 and 2018. From root cause failure studies, both pipeline failures were due to combination of external force (from geohazards), girth weld defects and under-matched of girth weld. Post incidents in 2014 and 2018, PETRONAS implements strategies in-line with industry practices in managing pipeline integrity i.e. risk assessments, inspection and monitoring, integrity assessments, and repairs. As such, this paper will focus on the usage of Structural Reliability Assessment (SRA) and Quantitative Risk Assessment (QRA) as part of risk and integrity assessments portion of the strategies. PETRONAS selected SRA and QRA due to availability of inspection, monitoring and operating data and also the fact that both methods consider uncertainties of data/parameters. Pipeline threats considered for the SRA and QRA are (i) girth weld anomalies (including under-matched effect), (ii) bend stress/strain (representing external force/geohazards), (iii) pipe buoyancy/stability at exposed river/stream crossings, (iv) dent/gouge (from third party), and (v) internal/external corrosion. This paper will dwell onto the evaluation and selection of appropriate equation of states for the threats taking into account the correct ‘load’ and ‘resistance’ factors. The resultant reliability and risk numbers were compared to target reliability based on procedures from ISO 16708 and target risk level from PETRONAS Technical Standard 16.71.04, respectively. At the end of the paper will discuss and elaborate the actions that need to be taken by pipeline operator consist of short, medium and long term measures aim to sustain the integrity and reliability of the pipeline.