PIPER ALPHA Worst Offshore Disaster 1998

Rig: Piper Alpha Platform

Date: July 1988

Operator: Occidental

Location: UK Continental Shelf

Fatalities: 167

The Piper Field was discovered by Occidental in January 1973, with the Piper Alpha platform becoming operational in 1976. Located about 120 miles north-east of Aberdeen, the platform initially produced crude oil. In late 1980, gas conversion equipment was installed allowing the facility to produce gas as well as oil. A sub-sea pipeline, shared with the Claymore platform, connected Piper Alpha to the Flotta oil terminal on the Orkney Islands. Piper Alpha also had gas pipelines connecting it to both the Tartan platform and to the separate MCP-O1 gas processing platform. In total, Piper Alpha had four main transport risers: an oil export riser, the Claymore gas riser, the Tartan gas riser and the MCP-01 gas riser.

Explosion and Fire

On 06 July 1988, work began on one of two condensate-injection pumps, designated A and B, which were used to compress gas on the platform prior to transport of the gas to Flotta. A pressure safety valve was removed from compressor A for recalibration and re-certification and two blind flanges were fitted onto the open pipework. The dayshift crew then finished for the day.
During the evening of 06 July, pump B tripped and the nightshift crew decided that pump A should be brought back into service. Once the pump was operational, gas condensate leaked from the two blind flanges and, at around 2200 hours, the gas ignited and exploded, causing fires and damage to other areas with the further release of gas and oil. Some twenty minutes later, the Tartan gas riser failed and a second major explosion occurred followed by widespread fire. Fifty minutes later, at around 2250 hours, the MCP-01 gas riser failed resulting in a third major explosion. Further explosions then ensued, followed by the eventual structural collapse of a significant proportion of the installation.
167 men died as a result of the explosions and fire on board the Piper Alpha, including two operators of a Fast Rescue Craft. 62 men survived, mostly by jumping into the sea from the high decks of the platform. Between 1988 and 1990, the two-part Cullen Inquiry established the causes of the tragedy and made recommendations for future safety regimes offshore. 106 recommendations were made which were subsequently accepted and implemented by the offshore operators.

Aftermath

A number of factors contributed to the severity of the incident:

• the breakdown of the chain of command and lack of any communication to the platform's crew;
• the presence of fire walls and the lack of blast walls - the fire walls predated the installation of the gas conversion equipment and were not upgraded to blast walls after the conversion;
• the continued pumping of gas and oil by the Tartan and Claymore platforms, which was not shut down due to a perceived lack of authority, even though personnel could see the Piper burning.

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