Stephen Galsworthy, Andrew Hutin, and Len Radford died in the blast

Wayne Barnes had been working at Corus' Port Talbot plant for five weeks when the incident happened in November 2001.

He said he had heard somebody shout "get out" after a door on furnace number five was blown off its hinges.

Len Radford, 53, from Maesteg, and Stephen Galsworthy, 25, and Andrew Hutin, 20, both from Port Talbot, died.

Mr Barnes, who was badly burned, told the hearing at Swansea's Guildhall that he had heard a bang and felt the walkway he was standing on start to sway.

There was a bright flash of light that was all around me Witness Wayne Barnes

Mr Hutin was standing at the bottom of a flight of stairs and began descending towards the door when it was blown off.

Mr Barnes said: "I looked behind me and saw Andrew going down the stairs. There was a bright flash of light that was all around me, then things got dark and visibility was poor."

He reported there being a lot of confusion on the radio as he tried to summon help.

He managed to negotiate the damaged walkways to reach furnace number four nearby, where colleagues gave him basic first aid.

It was like a volcano in there, quantities of burning material and slag Michael Divetta, steelworker

A dozen other workers also suffered serious burns when molten metal and superheated gases showered down on them.

Mr Barnes, who has not returned to work since the incident, told the inquest jury on Wednesday that he did not see Andrew Hutin again.

A colleague who was due to start work shortly after the blast told the inquest the scene was like a "volcano".

"The emergency services were everywhere, " said Michael Divetta.

"There was a lot of water and a lot of steam, it was chaos really.

"It was like a volcano in there, quantities of burning material and slag."

Mr Divetta told the jury how he helped to make the plant safe and was later involved in the "difficult" search for the body of Mr Hutin.

"We didn't see him, it was very difficult lighting, we were searching using torches."

Twelve other workers were injured when the furnace exploded

He told the jury a water leak had been detected the day before the blast, meaning that the furnace was not being fed with the tens of thousands of gallons of water needed to keep it cool.

Mr Divetta and other workers had checked the furnace and its coolers for the source of the leak before the furnace was finally taken "off blast", meaning that its performance was reduced to allow the fault to be repaired.

Sven Griffiths, an area technologist and the man in charge of the team, said the decision was later taken to close the furnace down until the problem had been solved.

But he said it was a fairly routine fault and had been dealt with in the normal manner.

He said: "It (the water leak) was a concern but my feeling at the time was that the shift team had responded correctly to the problem and once they had discovered that there wasn't enough water in the blast furnace the decision was made to take the furnace off."

Earlier in the week, the coroner's court heard that maintenance had been carried out on the furnace the day before the explosion.

On the day it happened, water was found to be flowing into the furnace and, at a meeting, it was a decided to discover the source of the leak.

The explosion happened about an hour and 15 minutes afterwards, coroner Dr David Osbourne said.

The inquest was adjourned to Thursday.