Workcover NSW prosecuted Drayton’s, and Mr Orgo’s employer, Perfab Engineering, in the District Court’s criminal jurisdiction for two breaches each of the Occupational Health and Safety Act.

The explosion blew the roof off the Pokolbin winery and was felt at various locations around the Hunter Valley on the morning of January 17, 2008.

Mr Orgo, 59, had been helping install an upgraded cooling system in the winery when he began welding on a stainless steel tank without knowing that it contained 9000 litres of ethanol known as SVR.

Vapours in the tank ignited causing a series of explosions that instantly killed Mr Orgo and Mr Drayton, 52, while assistant winemaker William Rikard-Bell suffered serious burns.

Judge James Curtis fined Drayton’s Family Wines a total of $210,000 and ordered them to pay the prosecutor’s costs after finding them guilty of failing to provide a safe workplace. Perfab will face a sentencing hearing in December.

The prosecution came after an inquest in 2011 that identified a series of ‘‘latent conditions and active failures’’ that led to the explosion.

Deputy State Coroner Hugh Dillon heard evidence that the winery lacked an occupational health and safety plan and had not conducted a fire safety audit.

There was no indication that the 27,000-litre tank was holding SVR, which had been delivered to the winery eight days earlier, the inquest heard.

The SVR had been pumped into tank 104 because welders were working on tank 106 when the delivery arrived.

A former assistant winemaker told the inquest that he had warned the Draytons in 1999 or 2000 that they should be careful about storing SVR while a former Cessnock City Council fire inspector told police that he attended the winery in 2002 to conduct an audit, but was refused entry.

Winery manager John Drayton disputed this claim at the inquest.

He declined to comment on the sentencing yesterday.