Pipeline Accident Report - Storage Tank Explosion and Fire

Glenpool, Oklahoma
April 7, 2003

NTSB Number: PAR-04-02
NTIS Number: PB2004-916502
Adopted October 13, 2004
PDF

Executive Summary

On April 7, 2003, at about 8:55 p.m., central daylight time, an 80,000-barrel storage tank at ConocoPhillips Company's Glenpool South tank farm in Glenpool, Oklahoma, exploded and burned as it was being filled with diesel. The tank, designated tank 11, had previously contained gasoline, which had been removed from the tank earlier in the day. The tank contained between 7,397 and 7,600 barrels of diesel at the time of the explosion. The resulting fire burned for about 21 hours and damaged two other storage tanks in the area. The cost of the accident, including emergency response, environmental remediation, evacuation, lost product, property damage, and claims, was $2,357,483. There were no injuries or fatalities. Nearby residents were evacuated, and schools were closed for 2 days.

The National Transportation Safety Board determines that the probable cause of the April 7, 2003, storage tank explosion and fire in Glenpool, Oklahoma, was ignition of a flammable fuel-air mixture within the tank by a static electricity discharge due to the improper manner in which ConocoPhillips Company conducted tank operations. Contributing to the extent of the property damage and the magnitude of the impact on the local community was the failure of American Electric Power employees to recognize the risk the tank fire posed to the nearby power lines and take effective emergency action.

The safety issues identified during the investigation of this accident are as follows:

  • Tank operations, including switch loading, at the ConocoPhillips tank farm.
  • The adequacy of emergency planning and emergency response by ConocoPhillips Company and American Electric Power.
  • The adequacy of Federal regulations and industry standards for emergency planning.

As a result of its investigation of this accident, the National Transportation Safety Board makes safety recommendations to the Research and Special Programs Administration, ConocoPhillips Company, American Electric Power, the American Society of Mechanical Engineers, and the Institute of Electrical and Electronics Engineers.

Recommendations

As a result of its investigation of the April 7, 2003, explosion and fire in Glenpool, Oklahoma, the National Transportation Safety Board makes the following safety recommendations:

To the Research and Special Programs Administration:

Revise the emergency response planning requirements in the pipeline safety regulations to include coordination with electric and other utilities that may need to respond to a pipeline emergency. (P-04-07)

Issue an advisory bulletin to liquid pipeline operators to validate the accuracy of their tank strapping tables. (P-04-08)

To ConocoPhillips Company:

Revise your storage tank operating procedures to include instructions for minimizing the possibility of creating a flammable atmosphere and the occurrence of a static discharge inside a tank after a floating roof has been either intentionally or unintentionally landed, especially for tanks where switch loading is likely to occur. (P-04-09)

Evaluate your storage tank operating procedures and make the revisions necessary to ensure that product flow rates in both the tank fill line and the discharge nozzles are restricted to provide a level of protection against excess static electricity that is at least commensurate with industry standards. (P-04-10)

Revise your emergency response plan for the Glenpool South tank farm area and similar locations where ConocoPhillips Company facilities are near electric utilities to include preplanning with nearby electric facilities. (P-04-11)

To American Electric Power:

Revise your emergency response plan to include areas, such as the ConocoPhillips Company Glenpool South tank farm, where pipeline transportation facilities are near American Electric Power facilities, and include a requirement that the American Electric Power emergency responders communicate and coordinate with the on-scene agency in charge. (P-04-12)

To the Institute of Electrical and Electronics Engineers:

Revise the National Electrical Safety Code to establish requirements for operators to prepare and implement emergency response plans for electric facilities where an emergency may affect pipeline facilities or that may be affected by emergencies at pipeline facilities. (P-04-13)

To the American Society of Mechanical Engineers:

Revise the emergency response planning requirements in your gas and hazardous liquid pipeline codes to include coordination with electric and other utilities that may need to respond to a pipeline emergency. (P-04-14)