About 600 workers at the Dragon Liquefied Natural Gas terminal site in Waterston, Milford Haven, west Wales walked out on Sunday of last week over health and safety following the death of a worker.
The site shut down after 43 year old Peter Luff died on site.
Alan Card, Unite union representative told a mass meeting on Wednesday that their colleague Peter had died of natural causes.
He proposed workers in each of the contracting companies on the site should choose a safety officer to inspect the site with managers on Thursday morning.
Many workers were angry that it had taken a walkout to get a response from the Dragon management and returned to work Friday.