Glomar Arctic II photo: Copyright Al Donnelly, Iverness

An explosion aboard the Glomar Arctic II in January 1985 killed two men and caused about $2.3 million in damage.^1,2 The story is a typical one centered on temporary equipment and involving lack of procedures and training for operations, maintenance, and emergencies. Although this happened many years ago, and despite tighter rules, accidents like this are still happening all too frequently today.

Arctic II (also known as GSF [Global SantaFe] Arctic II) was built in 1982. It is a Frede & Goldman L-905 semisubmersible (semisub) rig, designed for a water depth of 1800 meters and drilling depth of 25,000 meters.³ During construction, the rig was inspected by the U.S. Coast Guard (USCG) to ensure adherence to U.S. Regulations. Det Norske Veritas (DNV) also cleared the vessel according to its rules and as the authorized authority for the U.K. Department of Energy.

Facts of The Case

In 1985, Global Marine operated the Arctic II, drilling its first exploratory well in the North Sea, 130 miles east-southeast of Aberdeen, Scotland, under a contract with Phillips Petroleum Company UK, Ltd. January 14, the day before the explosion, in accordance with well-testing provisions of its contract with Phillips, the Otis Pressure Control Company (Otis) testing crew opened the adjustable choke valve on the drill floor, allowing crude oil and gas to flow through for sampling.

The next day, with well testing in progress, the crew fully opened the adjustable choke valve over three minutes—from one-quarter inch to one inch. Gas passing through the choke system caused an extraordinary amount of noise. The drilling supervisor reported a much faster flow rate compared with other tests on the same well. At the burner, crude oil and gas were ignited but soon extinguished.

The drilling supervisor left the drill floow for the port crude oil burner to investigate the problem. When he returned, he smelled hydrocarbon gas in the drillers house on the upper deck. Despite the fact that a low-level alarm, a high-level alarm, and a gas alarm monitor activated, no well flow shutdown occurred. Neither Global's nor Phillips' procedures manuals had instructions to shut off well flow when a low-level automatic methane gas alarm sounded.

The rig master and toolpusher sampled the atmosphere in the drillers house, immediately confirming explosive conditions. Soon afterward, the source was confirmed to be gas entering through an overhead air vent. Meanwhile, the third assistant engineer investigated the alarm in the port ballast pumproom and reported that a brown substance was flowing from an air line, the air smelled foul, and, although no smoke was present, the air was thick with a brown haze.

Ten minutes later, an explosion occurred in the ballast pumproom.

Illustration: National Transportation Safety Board, Marine Accident Report²

Firefighting response was delayed because the explosion had broken the fire main piping, causing a loss of fire water pressure.

Nonessential personnel were soon evacuated by helicopter. Later, the bodies of the third assistant engineer and chief engineer were discovered near the pumproom where the explosion occurred.

The Investigation

The U.S. Coast Guard (USCG) and the National Transportation Safety Board (NTSB) both investigated the incident because Arctic II was registered in the United States; at the time, it was owned and operated by Global Marine North Sea, Inc., in Houston, Texas.

The NTSB's Marine Accident Report² stated that after being cleaned, the burner nozzle was improperly reassembled (reusing the already compressed gaskets instead of new ones) and was not fully seated. This caused the fracture in the burner tip, allowing hydrocarbons from the well to contaminate the rig's compressed air system through the fracture in the burner tip. Wax and other solids in the crude oil obstructed nearly half of the air outlets in the burner nozzle and the crude oil backflowed through the atomizing air piping and into the main compressed air piping system. The overpressured air receiver opened the pressure relief valve, releasing crude oil vapor into the pumproom. This vapor ignited.

The burners were portable, temporary pieces of equipment brought onboard and installed by the well-testimg company. Such portable, temporary industrial equipment, at the time of the incident, was not under the authority of any U.S. or U.K. regulatory requirements or any classification society rules addressing inspection, certification, or approval. And only permanent equipment on mobile offshore drilling units (MODUs) was addressed by USCG regulations.

Also, because the pumproom and propulsion room were not classified as hazardous locations, they did not require explosion-proof enclosures on electrical equipment. With numerous ignition sources, fire and explosion were virtually inevitable in the event of a gas leak.

NTSB Findings

The Board’s findings included:

• No operations or maintenance manuals were onboard for the burners or nozzle assemblies

• Otis maintenance procedures were inadequate and permitted reinstallation of compression gaskets that lose effectiveness after initial installation and compression

• Otis inspection procedures were nonexistent, and no U.S. or U.K. regulations or classification society rules addressed inspection, certification, or approval of portable, temporary industrial equipment

• Inspection, maintenance, and proper assembly of the crude oil burner and its components were left to the discretion and sole responsibility of the owner and operator of the equipment—Otis and its employees

• Otis failed to establish or require quality control procedures of the burner tips for strict adherence to their design specifications during manufacture 

NTSB Recommendations

The Board’s recommendations included:

• Otis develop and implement:

o    Comprehensive inspection, maintenance, and assembly procedures

o    Quality control standards and procedures

o    Revised operating procedures requiring a dedicated, separate compressed air source and a device that prohibits backflow of hydrocarbons

• The USCG amend its regulations for MODUs to include required inspection of crude oil burners and their components

• The International Association of Classification Societies:

o    Amend rules to include a requirement for certification and inspection of crude oil burners and their components

o    Require that compressed air supplied to such equipment is from a dedicated, separate compressed air source

• Global Marine revise operations manual and Phillips develop MODU operating procedures to include shutting off well flow when a low-level methane gas alarm is sounded 

Lessons Learned

The primary lesson here is “pay now or pay later.” Invest now in developing and implementing policies and procedures, in training and re-training, and in regular maintenance to avoid potentially larger future payouts in human lives, damaged or destroyed assets, environmental damage, ruined corporate reputation, or regulatory fines.

Many tools exist to help in these areas, such as:

• Hazard identification (HAZID) analyses

• Hazard and operability (HAZOP) analyses of procedures

• Job-site risk analyses (JSAs)

• Safety-critical element (or system) identification

• Development of associated performance standards and written schemes of examination

• Safety cases

• Accident and incident investigations

IRC Risk and Safety can help your safety program with these and other risk assessment tools and health, safety, and environment (HSE) management plan.

References

  Visit IRC's website for information about our hazard and risk assessment and management services.