Hydrogen fire in an oil refinery

The regular maintenance of the hydrogen production equipment had been completed and the plant was about to start up. At this point, fluid mainly composed of hydrogen was sent via a pipe to the converter which converts carbon monoxide to carbon dioxide.
This pipe was not used in operation, but only to heat up the converter during startup after maintenance.
The pipe opened, causing the hydrogen gas to leak and ignite. The failure was due to external corrosion of the pipe. The pipe was insulated, but the insulation had been damaged in the area where the failure occurred. The damage of the insulation was caused by the interaction with the material of the walkway. This caused a notch in the upper part of the insulation, through which rainwater could access and corrode the external surface of the pipe.

The INITIATING CAUSE was external the corrosion of the hydrogen pipe, which caused the loss of confinement.

The ROOT CAUSE may have to do with a lack of proper inspection, which failed to identify the progressive corrosion of the pipe. However, because of the insulation around the pipe, the real extension of the corrosion progress would have been hidden to a simple visual inspection. The damage to the insulation should have been avoided in first instance. The interaction with the structure of the walkway was a mistake which could have been avoided during installation.

pipe

A worker was measuring the temperature at the hydrogen production unit

Deterioration of pipes and pipe components at high temperature due to external corrosion is a recurrent event in chemical plants. To reduce heart loss to the environment, the pipes are usually covered by layers of insulation material. This makes very difficult the early detection of degradation signals just by visual inspection.
It would be important, nevertheless, to monitor and report any sign of loss of protection functions to operation managers, for possible further measures.