The Australian Manufacturing Workers Union formally requested access to the site more than a month ago. At the time Chevron Corporation confirmed it was talking to the union "as part of usual union engagement with its members".
In a statement to Energy News, AMWU WA state secretary Steve McCartney said Chevron was "belligerent" about the union's legal right to be on site.
"Barrow might be on an island but it isn't the 51st state of the USA," he said.
"Chevron won't allow union representation anywhere near site," he said.
A Chevron spokesperson told Energy Newsthat the company had offered to facilitate an AMWU visit to Barrow Island to provide a briefing on the incident.
Energy News understands that the AMWU has requested a right of entry to the Gorgon construction site under Section 49I of the WA Industrial Relations Act and does not regard a briefing from Chevron as sufficient.
Under Section 49I of the Act an authorised union representative may investigate any suspected breach of the WA Occupational Safety and Health Act.
They may inspect any documents kept by the employer and inspect work and material that are related to the suspected breach.
McCartney said Chevron's intransigence is the only thing holding up access to the site.
"The AMWU has an obligation to our members and we will continue to seek access to the site to ensure that Chevron, a company who think they can negate their responsibilities under Australian legislation, is held to account," McCartney said.
How serious was the leak?
The AMWU is also concerned Chevron has trivialised the issue, which is adding to the concerns of their members.
"Chevron claims it was only a minor gas leak, but the union members on the job know that the only difference between a gas leak and a major catastrophic incident is the absence of an ignition source," McCartney said.
It was reported that the AMWU alleged a failed weld on a valve casing (called a trunnion) caused the gas leak that forced the plant to close.
The WA Dangerous Goods Safety (Major Hazard Facilities) regulations that apply to Gorgon specify that any loss of containment of a "Schedule 1 substance" - which includes methane - is classified as a "major incident".
While Chevron did not respond to Energy News' question of what criteria the company used to classify this incident as a minor leak, a spokesperson said that no safety breaches occurred, nor were any employees put at risk.
"There were no injuries as a result of this minor event," the spokesperson said.
"Chevron elected to notify the regulator as per the normal process and precautionary measures were taken to ensure the safety of personnel at all times."
"In early July, we took a short shutdown to address a number of issues and repair a minor leak. Production resumed mid-July, and the plant has been running smoothly since that time."
Yet McCartney remains unsatisfied.
"Our members have for a long time raised issues associated with mental health from the FIFO lifestyle and it is in the back of their minds every time they board a plane that something may go wrong and Chevron have done little to alleviate their concerns," he said.
Gorgon shipped its first cargo in March but was forced to shut down soon after, due to what Chevron has described as a "technical issue" with the propane refrigerant circuit.
It had hoped to send four cargoes soon after restoring output, but the leak threw the schedule into disarray, halting production soon after it resumed in mid-June.
The facility located on Barrow Island loaded its second cargo on July 3. Production from Train 1 recommenced later that month.
Train 2 is expected to begin production around the end of the year, with Train 3 expected to be finalised in mid-2017.
The project, one of the largest LNG developments in the world, was sanctioned in 2009 at a cost of $US37 billion with first gas planned for 2014.
In December 2013 Chevron updated the cost estimate to $54 billion and the first gas date to mid-2015.
Chevron's interest in Gorgon is 47.3%. It shares the project with ExxonMobil (25%), Shell (25%), and Japanese customers Osaka Gas (1.25%), Tokyo Gas (1%) and Chubu Electric Power (0.417%).