Technical and Engineering Challenges Faced in Design of the Gelugor Mainline, Penang, Malaysia

PETRONAS Gas Berhad (PGB), a listed partly-owned subsidiary of PETRONAS is undertaking the Peninsular Gas Utilization Project - Stage III (PGU III). The PGU III Sector 2 & 3 project extends from Lumut, Perak to Pauh, Perlis on the West Coast of Peninsular Malaysia, with two laterals, the Gurun Lateral and the Penang Lateral. The Penang Lateral is further divided into the Prai Lateral, Gelugor Mainline and the Gelugor Tenaga National Berhad (TNB) Meter Station project individually. This paper will focus its’ discussion on the technical and engineering challenges faced in the design of the Gelugor Mainline Project. The Gelugor Mainline consist of about 7 km NPS 24 gas pipeline which runs from TNB Prai Power Plant of the mainline to TNB Gelugor Power Plant on the Penang Island. The pipeline is planned to operate at high pressure. The pipeline route traverses complex terrain with varied seabed lithology with depth up to 16m. The pipeline will cross active shipping lane, zones of live electrical cables, extensive system of submarine pipeline, mudbank and areas susceptible to mass gravity flows. There is also an area subjected to future development with an expected 170 kN/m2 distributed load with 3 m covers required which is an expressway and Light Rapid Transportation (LRT) system, the proposed development of a “Vision City” is also a few meters away from the pipeline. The pipeline also passes by an environmentally sensitive area that includes the rearing of caged fishing activities. It is essential for the project team to determine and investigate the variable risks to the pipeline in order to take appropriate evasive and mitigating action in design. This required comprehensive survey activities in the busy shipping straits. The paper will explore and detail out its’ study starting from the description of the design concept to the varied environmental challenges. This paper aims to describe the route selection process, the pipeline design process and outline some of the specialist techniques employed in the design construction of the Gelugor Mainline, Penang, Malaysia. In nearly every major project a drive for cost and risk reduction results in a number of new ideas with varying degree of impact. Hence, the following areas will be elaborated and presented in greater details: • Pipeline Design. • Pipe-lay vessel. • Pipeline installation methodology.