Explosion in an analytical laboratory

An explosion and fire occurred on an offshore platform when using gas analysers to analyse the gas extracted from the borehole.
The analysers were part of a mud logging unit which was being assembled. Gas analysers had been calibrated, and the flame ionization detection (FID) and total hydrocarbon analyser (THA) modules were left in operation so that they could stabilize. Personnel were connecting the outside sample points and drains to the unit when the explosion occurred.

The FID instrumentation used in the mud logging unit required hydrogen gas to serve as the fuel for the flame within the instrumentation. The reason for the explosion was the release and ignition of hydrogen from the hydrogen connection between the hydrogen bottle to the FID. The leak was further fed by hydrogen from the bottles, which could not be isolated.

The INITIATING CAUSE was the failure of the hydrogen supply line.
The piping and hose connections used to supply the hydrogen to the unit were neither pressure tested nor checked for leaks. The unit had no gas detection equipment installed to detect either hydrogen or test/sample gas. The compressed hydrogen bottle did not have any shutdown equipment installed to prevent flow in case of a leak from downstream equipment. In addition, the inside connection to the detection modules consisted of polyurethane hose, which was either blown loose or burned off the connector during the initial explosion and fire. This allowed the hydrogen to continue to flow and feed the fire in the mud logging unit.
The ROOT CAUSE was an absence of a risk assessment and a safety design, worsened by a lack of inspection and testing procedures.

Flame ionisation detector, hydrogen supply line, H2 bottle

DESCRIPTION OF THE TERMS:
Mud logging = creation of a detailed record of a borehole by examining the cuttings of rock brought to the surface by the circulating drilling medium.
FID = A flame ionization detector is a scientific instrument that measures analyses in a gas stream.

Unknown consequence, although the fact that manual operation by operators were performed when the fire and explosion took place could imply injuries and the total destruction of the analytical equipment.

The incident investigation report requested the following modifications:
1. Lessees, operators, and contractors shall consider equipping compressed hydrogen and other flammable gas bottles or generators that supply gas to mud logging units with automatic shut-off systems.
2. Lessees, operators, and contractors shall consider equipping mud logging units that use FID instruments with a gas detection system that provides an audible alarm and shuts in the gas supply when the ambient air reaches the lower explosive limit.
3. Lessees, operators, and contractors shall consider equipping FID instrument systems with automatic shut-off systems to shut down both the gas supply and the instrument itself should a flame failure occur.
4. Lessees, operators, and contractors shall consider equipping mud logging units with a positive purge system that sounds an audible alarm and shuts down the unit when the purge pressure falls below a minimum level.
5. Lessees, operators, and contractors shall review the piping supplying combustible gases to mud logging units to ensure that the piping is constructed of appropriate material.
6. Lessees, operators, and contractors shall check the piping supplying combustible gases to mud logging units to ensure that there are no leaks after installation of the piping.