The Northern Territory Government has recently selected the proponent, pipeline route and lead contractor for the construction of the North East Gas Interconnector (NEGI) pipeline. As all parties gear up for construction, it’s time to consider the benefits of selecting quality equipment for a safe and long-lasting installation.  

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The NEGI involves the construction and operation of a 622 km buried high pressure gas pipeline from Tennant Creek in the Northern Territory to Mount Isa in Queensland. Associated aboveground facilities at various locations will also be built along the pipeline.

Jemena, the chosen proponent for the project, has submitted their Environmental Authority for a Petroleum Pipeline Licence: Supporting Information published a list to the Environmental Authority which outlines each of their environmental considerations, including those which mention underwater crossings and hydrostatic testing.  

According to Jason Linaker, Managing Director at kwik-ZIP, these underwater crossings will require trenchless installation, where associated centralising techniques of the pipe must be considered.

“High pressure gas pipelines are generally very heavy, so associated pipeline equipment needs to be of the highest quality and strength.

“Spacing systems for the pipeline will need to be able to withstand the weight of the pipeline without breaking or bending.

“Abrasion is also something to consider as the weight of the pipeline can put pressure on the runner and result in significant wear if not considered in the spacer design.”

Mr Linaker said that as the NEGI pipeline is to be made from steel, corrosion resistance of the chosen spacers should also be a top consideration.

“Spacers made from inert materials would be the optimum choice for this type of installation.

“Not only do inert spacers remain free from corrosion damage themselves, but they will also prevent wear on the pipe casing.”

According to Jemena’s submitted licence, corrosion of the spacer should also be considered when looking at soil conditions. Acid sulphate soils (ASS) are found below the water table, and become acidic if disturbed and exposed to oxygen.

“The acidic soil conditions in the NT require a non-metallic spacer so as to not corrode in the harsh environment.”

“A metallic spacer would be subject to severe corrosion if coming into contact with acid sulphate soils that may be left behind in the annulus after installation of a road or river crossing. Even stainless steel is subject to accelerated corrosion from such soil conditions. Such corrosion can be transferred via the metallic spacer to the steel pipeline itself. Inert non-metallic pipe spacers are resistant to such conditions.

About the project

Northern Territory Chief Minister Adam Giles said the NEGI pipeline will connect the ever-increasing energy needs of the east coast with the vast gas reserves in the Territory.

“Without this pipeline, the populated parts of Australia would have huge difficulty securing their energy needs.”

It is estimated the Territory has more than 200 trillion cubic feet of gas – potentially enough to power Australia for more than 200 years.

The total cost of the pipeline is estimated at $800million and construction of the NEGI pipeline will create more than 900 jobs during construction, 600 of which will be for locals and offer up to 100 contracts for local businesses worth about $112million.

Jemena expects construction of its 14 inch pipeline to be completed by 2018.