Fire on a compressor of a hydro-treatement unit

The event involved a recycle gas compressor of a hydro-treatment unit of a refinery. During recommissioning, the compressor was over-pressurised and the cylinder head was blown off, resulting in an explosive decompression and fire. 

The discharge valve had been installed in the wrong direction.

Investigations into the accident showed that the INITIATING CAUSE was the installation of one of the discharge valves in the reverse direction. 

This results in the build up of pressure within the cylinder. The criticality of the task to replace the valve had not been understood or reflected in procedures. Although the compressor was purchased according to the API 618 standard, which requires a design that prevent valves from being installed in the wrong direction, the equipment did not meet specification. The ROOT CAUSES were shortcoming in maintenance procedure and in quality assurance when dealing with contractors and manufacturers.

recycle H2 compressor

The ICHEME report used the term Hydrofiner: this is an industrial unit, primarily in oil refineries, that uses hydrogen and catalysts to remove impurities (sulphur, nitrogen, aromatics) from petroleum fractions, improving fuel quality (like gasoline, diesel, jet fuels). The more generic term is catalytic hydrotreating process to "clean" oil products, making them cleaner burning and more valuable. The report does not specify the composition of the process gas, but it is known the the recycled gas consists mainly of hydrogen with traces of H2S.

Production losses and repair costs were estimated at $500,000 (1995) (£318,300) and $400,000 (£254,600) (1995), respectively.

Quality control and assurance of the products obtained from third parties is critical to be able to manage risks during the operation of the plant. Therefore, the company had to review and improve the procedures identifying and controlling components received from 3rd parties.