Northern Gas Pipeline Design

The 623km Northern Gas Pipeline was a critical Australian gas transmission project providing a pathway for gas fields in the Northern Territory to the eastern Australian gas markets. The pipeline traverses a remote region from Warrego (45km northwest of Tennant Creek), in the NT, to Mount Isa, in Queensland, and covers a diverse environment, including semi-arid land, major water crossings, road and rail crossings and sections of heavy rock.

GPA completed design calculations for various diameters, before proceeding with the detailed design for the selected DN300 class 900, API 5L Grade X70 PSL2 pipeline with a 0.8 design factor. GPA completed all aspects of detailed design for the transmission pipeline and associated pipeline facilities, such as the launcher/receiver facilities, three intermediate remote main line valve and future compression sites, including design of the impressed current cathodic protection system and management of tellurics.

The project demonstrated GPA’s capability to execute detailed design for a large, long distance major gas transmission pipeline. GPA also supported the specification and inspection of line pipe supply from a Chinese linepipe supplier, including development of the supply specification, manufacturing and testing requirements.

GPA also completed and facilitated the Safety Management Study using our in-house SMS database package, GPA Guardian software, to identify, document and manage potential threats to the integrity of the pipeline, for design, construction, and commissioning phases. As well as completing further risk assessment for failure threats using Layers of Protection Analysis (LOPA).

GPA’s in-depth knowledge of the Australian Standard AS2885 and direct involvement of the design team in the development of the latest revision of AS2885.1 ‘Pipelines – Gas and Liquid Petroleum, Design and Construction’, and our ongoing roles in leading and contributing to pipeline research via the Energy Pipelines CRC and Future Fuels CRC enabled the project to apply best practice pipeline engineering design.