An explosion occurred at 5:25 p.m. in a workshop that was being dismantled at a plant that makes nitrocellulose for civilian use. The explosion happened while a specialist contractor was removing an overhead pipe while on a cherry picker. The basket of the cherry picker was 6 m above the floor. The worker’s face and left arm were seriously injured, and two of his colleagues working on a deck at the same level were slightly injured. The explosion triggered the cherry picker’s safety device. The injured worker was rescued by firefighters. The roof of the building was partially blown off. Dismantling operations were halted.

As a significant length of the pipe was not supported by clamps, several cuts were necessary to remove it. Although the pipe had been cleaned before the work was started, traces of dry nitrocellulose may have deflagrated during cutting.

More stringent procedures had been implemented following a similar accident at the site in 2011 (see ARIA 40771). These included cleaning the pipes with a high-pressure washer fitted with a dirt blaster and checking the pipes with an inspection camera before removing them.

The pipe that caused the accident had a ‘large’ diameter (250 mm). It seems that the cleaning of this pipe had been less thorough than with previous pipes of smaller diameter. On the day of the accident, the inspection camera had not been used because of a screen malfunction. Trained in UXO hazards, the operators were probably overly confident in the cleaning step.

The contractor improved its cleaning operations for pipes of all sizes and clarified its procedure (formal monitoring of cleaning steps, double cross-checks before removal, pipe removal formally prohibited without first conducting an inspection and dousing adequately with water, etc.).