Gas leaks like that which crippled North Island businesses last week could become more common as the Maui pipeline gets older, a civil engineering expert is warning.
The damaged section of the pipeline which supplies gas to the upper North Island was fixed over the weekend.
During the repair large scale commercial users were told to stop burning gas, raising fears of food shortages and the loss of millions of dollars of revenue.
Associate Professor of Civil Engineering at Unitec, Jonathon Leaver, told TV ONE's Breakfast the priority now is to find out what caused the leak.
"The immediate issues that come to my mind are thermal expansion of the pipeline and fatigue in that crack weld," he said.
"There's also earth movement and the chemical composition of the gas which can cause embrittlement of the welding - but to my mind when one weld fails you must determine the cause of that weld failure so you can undertake a risk analysis of other sections of the pipe."
He said it will now be up to the pipeline's owners, Maui Developments, to undertake a risk analysis of every section of the pipe to determine which areas may be vulnerable to future leaks.
Once this has been done the company will be able to decide whether it needs to take action to ensure the future supply of gas.
Options could include a second pipeline, or creating back-up sections for vulnerable areas of the pipe.
"The issue is around motivation - are Maui Developments motivated to increase security of supply or are they comfortable with simply persisting with interruptions at various intervals," he said.
"Those interruptions may be more frequent as the age of the pipeline increases but it's difficult to say."
A back up pipe with the same specifications as the Maui pipeline would cost in the region of $1 billion, Leaver said, and the company will need to ensure its shareholders are happy with their decision.
In the meantime Leaver said the company should increase the number of ground inspections of the pipe it carries out as they are the easiest way to spot gas leaks.