A company has been convicted of health and safety breaches in relation to the Buncefield oil depot explosion in Hertfordshire in December 2005.
Motherwell Control Systems 2003, Liverpool, was convicted at St Albans Crown Court of failing to ensure employees were not exposed to risks.
The jury at St Albans Crown Court is considering its verdict in the case of TAV engineering of Guildford.
The blast injured 43 people and homes and businesses were destroyed.
Motherwell Control Systems, of Castle Street, which is in voluntary liquidation, was not represented at the court.
The explosion, which measured 2.4 on the Richter scale and could be heard 125 miles away, happened after a massive vapour cloud ignited when 250,000 litres of petrol leaked from a tank, the court heard.