A steel company has pleaded guilty to failing to make a risk assessment before two men were killed at its plant.
Peter O’Brien, 51, from Llanishen, Cardiff and Mark Sim, 41, of Caldicot, Monmouthshire, died at the Celsa UK site in Cardiff in November 2015.
Cardiff Crown Court heard a second charge of breaches of health and safety laws will lie on file.
A trial, scheduled to last four to six weeks, will now no longer go ahead.
Another worker, Darren Wood, was seriously injured in the explosion.
The prosecution was being brought by the Heath and Safety Executive (HSE).
The judge Neil Bidder described it as a “very, very serious case”, adding: “The two men went out to work and never came back”.
He said the company could expect a substantial financial penalty when it returns for sentencing on 4 October.