A broken gas line near the bottom of a 1,000 gallon ASME stationary propane tank in agricultural service has resulted in a gas-fed propane fire. The fire is impinging on the outside shell of the tank below the liquid level. The tank's relief valve is functioning intermittently and a plume of gas has ignited and is burning above the relief valve.
The nearest exposure is a horse barn 75 feet away from the tank.
ASME stationary tanks can be found at homes and at commercial, industrial, and agricultural facilities. Stationary tanks can also be found at service stations for refilling recreational and motor fuel tanks. Stationary tanks are normally filled from a bobtail truck.
Most stationary tanks are built by welding two heads to a barrel. Their capacities typically range from 250 to 2,000 gallons, with most domestic tanks being less than 1,000 gallons.
ASME stationary tanks are designed for different working pressures depending on their intended service. The normal working pressure for stationary propane service is 250 psig.
Fittings for valves under 2,000 gallons capacity are normally threaded. Threaded attachments are commonly 1/4 inch to 2-1/2 inch female normal pipe thread (NPT) with some special flanges for liquid level gauges. Openings are normally located on top of the tank.
A 1,000 gallon propane tank requires a minimum continuous flow of 100 gallons per minute (gpm) to adequately cool the tank shell. This can be provided through a 1-1/2 or 1-3/4 inch attack line flowing 100 gpm or higher.
Two handlines are recommended to attack and extinguish the fire. The first line should be placed in service as soon as possible and be played evenly on the tank shell to keep it cool while the second line is being deployed. A third back-up line is recommended to protect the attack crews and protect exposures. The back-up line should be in service before the attack begins.
Crews should continue cooling the tank shell until the relief valve closes. Once the relief valve has closed, both attack teams will simultaneously advance toward the burning tank from the side of the tank, under the protection of fog patterns (a.k.a. power cones). Nozzle patterns should be adjusted so that they overlap and provide the broadest possible protection as crews advance.
When the tank is reached, a designated crew member should close the valve on the tank. This will isolate the broken gas line. Residual gas inside the broken line will burn off quickly and the fire will be extinguished.
This is a top-perspective view of the incident area. Its purpose is only to get the general idea of the incident and surroundings.
In this section, we present an animated version of the incident.