Two significant storage tank fires occurred in Europe the week of May 30, 2011—one in Gibraltar and one in southwest Wales. Tragically, the Wales explosion and fire resulted in four people dead and a fifth in critical condition. Coincidentally, last week I was working on a project reviewing hazards and risks associated with some new onshore oil and gas production facilities which had a number of oil storage tanks.

So I wondered just how common storage tank fires are, and I did some quick research on the Internet— facilities which had a number of oil storage tanks. I was a little surprised by what I found.

Three Months of Storage Tank Fires

In the past three months at least 9 fires involved storage tanks. Many of them escalated to involve multiple tanks, some tragically resulted in serious injuries and fatalitites, and all resulted in significant property damage and business interruption. In addition, while this bulletin was being prepared, another fire involving storage tanks occurred during maintenance at a Texas refinery on June 7th.

Causes of Storage Tank Fires

The causes of storage tank fires vary; however, the following figure provides a breakdown based on approximately 250 fires (A study of storage tank accidents, Journal of Loss Prevention in the Process Industries 19 (2006) 51–59).

A significant amount of literature relates to prevention, control, and mitigation of storage tank fires. A few stood out for me:

• Center for Chemical Process Safety (CCPS) Guidelines for Facility Siting and Layout (2003)

This document provides guidance on safe layout of facilities and separation distances. It interested me to note that the storage tank separation distances recommended by CCPS are significantly greater than those in the National Fire Protection Agency (NFPA) 30 Flammable and Combustible Liquids Code (2008).

• UK HSE Safety and Environmental Standards for Fuel Storage Sites (2009)

This document provides guidance applicable to storing gasoline or similar Reid vapor pressure (RVP) materials (such as condensate) and incorporates the findings from the Buncefield storage tank site explosion and fire.

• UK HSE HSG176: The Storage of Flammable Liquids in Tanks (1998)

While this is an older reference, it provides good information about storage tank layout and fire safety design. For recommended minimum tank separation distances the guidance states: If a serious fire develops involving one tank in a group then it is unlikely that these between-tank separation distances will prevent damage or even destruction of the adjacent tanks. However, they should allow sufficient time for emergency procedures to be implemented and for people to be evacuated from areas threatened by the incident.

• US Chemical Safety Board, Death in the Oilfield (2006)

This short video depicts an incident wherein three workers were killed while performing maintenance on a storage tank. The video discusses the causes of the accident and recommended findings.

Lessons Learned

When dealing with storage tank fires, unless workers are specially trained with the appropriate equipment, it is especially important to remember that municipal fire departments are not equipped mentally or physically to put out tank fires. Also, emergency responders should be aware that after being extinguished, tank fires often can re-ignite.

Since a significant number of tank fires are caused by maintenance and hot work, before conducting any tank maintenance activities, robust procedures should be in place that include:

• Risk assessment (job safety analysis) before conducting any work
• Training and competence of personnel
• Hot work controls and elimination of flammable atmosphere, including isolation, purging, gas testing, and control of ignition sources
• Adherence to minimum separation distances given in codes and standards such as NFPA 30 is unlikely to prevent escalation from one tank to another in case of fire
• Provide adequate separation from tanks to site boundary, process equipment, loading areas, and buildings.

In the absence of facility-specific risk assessment, CCPS Guidelines for Facility Siting and Layout (2003) provides the most conservative guidance.

• The only effective means to extinguish a tank fire is foam, and even this may not work for large fires
• The strategy to minimize potential for escalation between tanks should consider a combination of separation and fire suppression
• Consider segregating groups of tanks if large separation distances between individual tanks in batteries is impractical, as in the figure below

• For higher risk tanks (e.g., those containing highly flammable liquids), provide an automatic overfill prevention system that is physically and electrically separate and independent from the tank gauging system
• Periodically test overfill protection systems; long periods of inactivity may render them ineffective
• Locate fire-safe isolation valves close to the piping inlet and outlet of tanks
• Remotely operated shut-off valves provide the safest means to isolate the large inventories in storage tanks
• Shut-off valve closures should be initiated from a point remote from the valve itself and a sufficient distance from potential fires for which they are intended to safely isolate inventory
• Provide tertiary containment measures to prevent escape of liquids from the site and threatening a major accident to the environment
• Design site drainage and grading to assist in containing spills that may overflow secondary containment

More Information on Specific Storage Tank Fires

For more information on recent storage tank fires, including photographs and practical lessons from major accidents, please visit the ERM Risk Practice blog.

About the Author

Jeremy Goddard is the Chief Technology Officer for the North America Risk Practice at Environmental Resources Management (ERM). Jeremy provides technical direction, oversight, and quality assurance to projects. He has more than 20 years of experience in HSE management and risk assessment in the offshore oil and gas industry, gained mainly within theUK,Australia, Middle East, and theUSA. His experience covers a wide range of areas and project phases, including design and operations safety cases, a range of fire safety analysis (FSA) studies focused on influencing and verifying design, and performance standards, written schemes, and integrity management plans. He has an excellent understanding of project economics and the competing requirements of revenue, expenditure, schedule, and HSE management. Jeremy also has taken an active role in the development of proprietary software.

The ERM NA Risk Practice offers a wide range of safety and risk management services varying from small, one-off studies to complete management of safety and risk for major field development projects. The company’s approach to risk assessment is pragmatic- the work should be easily read, and accurate. ERM delivers solutions that fit the application and are in each client’s interest. The company’s portfolio attests to its extensive expertise in onshore and offshore oil and gas project support including concept selection, construction, operation, and decommissioning. ERM has a broad range of core competencies that span the gamut of risk and safety analyses- from broad scoped safety case preparation to specific, individual studies.

Photograph: Shine Energy 6 by Flavio Takemoto,Brazil.

Return to the EHS Journal Home Page