After twelve months of design and meticulous planning, Zinfra gas pipelines and facilities crews worked at full tilt to construct the new regulators and pipework at AusNet Services’ Corio City Gate in Victoria.


This project was significant for AusNet Services as the Corio City Gate is their most critical gas asset, in terms of the number of customers it supplies and as a major supplier of natural gas to the region.

The gas infrastructure was originally constructed in 1971 and is the sole supply of gas to Geelong, Torquay and the Bellarine Peninsula – over 200,000 customers. The City Gate reduces gas pressure from 7200kPA to 1700kPA as it arrives from the APA-owned 350mm Brooklyn to Corio transmission pipeline, and then injects this gas into the Corio to Point Henry pipeline.

The age of the asset, as well as increasing demand, dictated the need to upgrade the regulators to ensure consistent and reliable pressure control. Zinfra was engaged to design, procure and construct the pipework.

To facilitate construction, the existing meter had to be bypassed by a temporary piping arrangement. This temporary bypass, however, could only sustain off-peak demands in the summer months, which meant all works had to be completed in the short month of February to avoid the risk of downstream loss of supply to customers.

To plan for this tight timeframe, Zinfra’s work started nearly a year earlier when their in-house design teams put pen to paper to design the pipework.

Designs were planned to meet AusNet Services’ piping specifications and requirements, and pipe stressing was then completed to ensure the new design was compliant and fit for purpose to all the relevant codes and standards around fabrication and constructability.

Approval of the final design was required from both AusNet Services and APA Group before fabrication could commence. These approvals, along with a detailed project plan, all procurement and all off-site fabrication works and commissioning plans had to be in place well before construction commenced.

The scope of the project included the removal and replacement of the existing Welker jet and jet stream regulators, their respective legs with Gorter R100 regulators, as well as the replacement and relocation of the outlet header to above ground.

Other works required included the installation of mechanical protection bollards to protect the new above ground outlet header and other assets on site, and the inspection of above and below ground piping transitions to inspect their condition and to repair and recoat as necessary.

Zinfra’s Delivery Manager for Gas and Water, Ben Gliwa, was delighted with the overall outcome on the project.

“This is a prime example of the high-quality facility and SMP construction work Zinfra is delivering in the gas sector. Not only was the project well managed from the outset, it met the client’s tight timeframe and was delivered without incident. We are very proud of what we have achieved here.”

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