The onshore pipeline portion of the Papua New Guinea Liquefied Natural Gas (PNG LNG) project traverses terrain with seismically active faults with potential soil displacements up to four meters. The resulting longitudinal strain demand exceeds 0.5% strain, thereby requiring use of the strain-based pipeline design method. This paper discusses the application of previously developed strain-based design methodologies to successfully qualify the PNG LNG pipeline system for a design tensile strain demand up to 3%, and flexibility to increase the design strain demand with additional restrictions on key variables impacting strain capacity at select locations. The qualification timeline, key engineering and project decisions, and lessons learned from this qualification effort are described.


Bringing energy to world markets can require constructing pipeline systems from energy resources geographically isolated from consumer markets by challenging terrain. The initial phase of the PNG LNG project is expected to produce 9 trillion standard cubic feet of natural gas. This requires an investment exceeding US$15 billion in the development of gas fields located in the PNG Highlands. There are four major components of the project: Facilities (wellheads and gas conditioning plant), Onshore Pipeline, Offshore Pipeline and LNG Plant. The onshore pipeline portion of the PNG LNG project includes a 293 km long gas pipeline that descends from approximately 2,100m to sea level, while traversing terrain with geotechnical challenges including slopes greater than 50% and seismically active fault crossings with potential soil displacements up to four meters (Figure 1). Crossing these active faults with buried pipelines results in pipeline longitudinal strains exceeding 0.5%. To safely design a pipeline to accommodate longitudinal strains above 0.5% due to differential soil movement requires use of strain-based design (SBD) in addition to conventional working stress design that sets the pipeline minimum wall thickness to withstand internal pressure.

This content is only available via PDF.
You can access this article if you purchase or spend a download.