oil storage tank explosions and fires

7/29/2019 Oil Storage Tank Explosions and Fires

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Oil Storage Tank Explosions and

Fires

The problem

During 2004 there were explosions and fires involving oil storagetanks at various sites. No serious injuries were reported but thepotential is there if the explosions occur during maintenance orloading of crude or produced water.

Contributing factors

The most common direct cause of the explosion and fire is allowingthe storage tank interior fuel oil level to fall below the heating tube.

(Figure 1). The fire tube heater in the tank continues to function andthe glowing tube eventually ignites the vapours above the liquid inthe tank. Other contributing factors are: The fire tubes are not always mounted on the tanks in the same

location or in an area where the trucker unloading the tank candetermine if the burner is functioning.

Some tanks have 2 fire tubes. Truckers may not be aware of this. Most tanks do not have a danger zone marking to notify truckers

of the level of fluids that must be maintained in the tank(Figure 2).

AL030 Alert 1February 2005


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Figure 1: Inside view of tank with fluids unloaded below the fire tube

Figure 2: Tanks having poor markings



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Most tanks do not have a low fluid level shut-off of the heatertube due to the cost of installation.

Often the loading of fluids is done during hours of darkness since

the truckers work on a 24-hour rotation. Many sites have poorlighting. The marker gauge is poorly marked on most tanks and the seam in

the center of the gauge board often catches the marker andprevents it from giving accurate tank levels. In order to check thisthe trucker must climb the ladder and lift and drop the gauge cableseveral times to ensure the marker is free. The trucker may not beinclined to do this.

Many tanks are not fitted with a pulley on the top that prevent thecable from jumping off. If the cable jumps off the pulley andjams, a false reading is given of the tank level.

Many of the floats used inside the tanks are a 4 by 4 timber.These can become saturated and sink into the fluid or become

loaded with sludge and give inaccurate fluid level readings. Many truckers work long hours with few days off and are

fatigued, leading to mistakes when loading at many different sites. Some truckers do not keep accurate records of fluids loaded, so

that the dispatcher can accurately determine when the next truckershould be dispatched by calculating the appropriate fluid level ofthe tank, based on well production.

Discussion

The Occupational Health and Safety Code, Part 10, section 163,paragraph 1, states:

An employer must develop procedures and precautionarymeasures to prevent flammable substances, or combinations ofthem, that are stored, handled, processed or present at a worksite, from igniting unintentionally.


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Recommendations

Workplace Health and Safetys investigation and engineering reviewof a number of tank explosions have determined that the followingpractices can help prevent future incidents: Oil storage tanks should have well marked danger levels and

gauge boards (Figure 3).

Figure 3: Storage tanks with good danger markings


Construction of and maintenance of the gauging system should beas fail-safe as possible, so as to give accurate storage tank fluidlevel readings.

The gauge boards should be located where they are easily visibleto the trucker loading fluids.

Loading areas should be well lit so truckers can see gauge boardmarkers.

Fire tube heaters should have automatic low fluid level shut-offcontrols.

Truckers should have clear instructions on manually shuttingdown a fire tube heater if they come upon a site where the storagetank fluid levels are below the fire tube.

Storage tanks should be regularly cleared of produced sand as thesand can lead to false readings of fluid levels.


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Contact us:

Province-Wide Contact Centre

Edmonton & surroundingarea:(780) 415-8690

Throughout Alberta:1-866-415-8690

Deaf or hearing impaired

Web Site

www.worksafely.org

In Edmonton: (780) 427-9999or 1-800-232-7215

throughout Alberta

Getting copies of OHS Act, Regulation & Code:

Queens Printer WorkplaceHealthandSafety www.qp.gov.ab.ca www.whs.gov.ab.ca/whs-legislation

Edmonton (780) 427-4952Calgary (403) 297-6251

Call any Government of Alberta office toll-freeDial 310-0000, then the area code and telephone number you want to reach

2006-2007, Government of Alberta, Human Resources and Employment

This material may be used, reproduced, stored or transmitted for non-commercial purposes. The source of this material must beacknowledged when publishing or issuing it to others. This material is not to be used, reproduced, stored or transmitted forcommercial purposes without written permission from the Government of Alberta, Human Resources and Employment. This materialis to be used for information purposes only no warranty express or implied is given as to the accuracy or the timeliness of the materialpresented. In case of any inconsistency between this document and the Occupational Health and Safety Legislation, the legislation willalways prevail.

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oil storage tank explosions and fires

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