Explosion in a refinery

The event occurred at a hydrogen tank (another source reports a 'conduit in an enclosed space') of a hydrogen generation unit of a refinery. The explosion caused a flare and a displacement of air that threw the contract workers against the refinery's metal structure.

The workers were using an electric rotary sander on the inside the tank which had been had been drained three days before. The workers had already done previously the same work without incident.

The INITIATING CAUSE was an explosion inside a hydrogen tank, which was still containing hydrogen despite workers were working in it.

According to the sources, the possible causes could have been "inadequate maintenance, failure of following procedures, lack of work procedures or procedures". Additional job related causes could also have contributed, such as mental and physical stress due to long shift and tight deadlines.

All these are plausible, however, absolutely no evidence is provided to support these theses. The ROOT CAUSES remain unknown.

hydrogen tank, pipe

Maintenance works were ongoing.

DESCRIPTION OF THE FACILITY
Acording to www.nsenergybusiness.com, tThe process units in the this refinery included an atmospheric distillation unit (ADU), a vacuum distillation unit (VDU), a catalytic cracking unit (CCU), a hydrodesulphurisation unit (HDS), a hydrotreating unit (DHTD), a hydrogen generation unit (HGU), a sulphur recovery unit (SRU), and a lubricant and paraffin plant.
According to the Oil and Gas Journal, the hydrogen generation unit has a hydrogen generation capacity of 1.1 million normal m3/day (approx. 100 kgH2/day). It produced high-purity hydrogen by SMR for for several downstream units within the refinery complex.

The injuries were severe.