Two men who were trapped in a "fierce fire" in a paint-spraying booth died because of a number of failings, an inquest heard.
Barry Joy, 56 and Daniel Timbers, 28, were killed while working at Harford Attachments in Norwich in July 2015.
An inquest jury concluded there were a number of failings at the plant including a lack of appropriate training in using the booth.
The two-week inquest heard from 80 witnesses.
The jury at Norfolk Coroners' Court also said there were numerous sources of ignition both inside and outside the enclosed work area at the site where the firm made buckets for diggers.
There was also a lack of reliable company records of staff carrying out specific risk assessments for working inside the booth, the jury decided.
Paint sprayer Mr Joy, of Spencer Street, Norwich and production operative Daniel Timbers, of Dereham Road, Norwich could only be identified through their dental records as their bodies had been so badly burned, the inquest heard.
Mr Timbers had been standing in for his father who was ill, the coroner said previously.
The jury concluded the men were killed by the effects of fire and the inhalation of the fumes of combustion.