First Gas plans two-day shut for Maui pipeline repair

Thursday 15th November 2018

First Gas is planning to shut part of the country’s biggest gas pipeline for two days to fix a damaged section near Whitecliffs, north of New Plymouth.

The company has built a 900-metre bypass which it is testing this week. It is also preparing to isolate the damaged section of the Maui pipeline near Pariroa so that it can be emptied of gas and the bypass tied-in over two days starting late Friday, Nov. 30.

First Gas chief executive Paul Goodeve said the company considered whether the work could be done with hot-tapping – connecting the bypass while the pipeline was still full of gas – but the terrain was too difficult to get the required equipment into the area safely.

Instead, the company will empty that section of gas. It has been working with major users, including Genesis Energy and Refining NZ, to reduce demand that weekend and ensure sufficient supplies for other users.

Goodeve said having two teams of welders working on the project should allow sufficient time to safely complete the connection, test the bypass and then refill the line with gas on Sunday evening in time for normal demand to resume on Monday.

“We’re confident that there’s enough gas in the system,” Goodeve told BusinessDesk. “But we wouldn’t want to have it down much longer.”

The 309-kilometre Maui pipeline is the main gas supply from fields in Taranaki and runs from Oaonui on the western Taranaki coast to Huntly. In 2011, a week-long unplanned shutdown – due to a leak near Pukearuhe – is estimated to have caused $200 million of losses after some of the North Island’s biggest milk, timber and meat processors cut production to conserve gas supplies for homes, hospitals and other essential services.

First Gas operates both the Maui line and the smaller Kapuni pipeline system that runs north and south of Taranaki.

Parts of those pipelines’ route around the broken northern Taranaki coast are prone to slow-moving landslips, which are monitored. They were the cause of the 2011 Maui shutdown and a similar outage on the line in 1977.

The latest damage is about 4.5 kilometres north of the site of the 2011 leak. A five-yearly internal inspection in April discovered an anomaly there and in September an inspection showed a five-metre section of the 75-centimetre pipeline had developed a crease due to movement. While there had been no loss of containment, there was a risk of failure.

Goodeve noted that gas demand north of Taranaki peaks in spring due to dairy processing. The company also worked with Transpower to ensure the pipeline repair avoided a shutdown of the high-voltage Cook Strait link. which the national grid operator plans the weekend before.

Goodeve noted the company still has the flexibility to defer the pipeline repair should some change in the power market require it.

(BusinessDesk)

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