How to Place a Nitrogen Blanket in an Outdoor Tank

Flammable storage tanks often use a nitrogen blanket for protection.

Many outdoor storage tanks contain liquid materials that react with oxygen and could form an explosive gas mixture. To combat this problem, industrial plants apply an inert gas to the vapor space above the liquid level to replace the air and oxygen with something that will not react. This is called a nitrogen blanket.

Things You'll Need

• Nitrogen regulator
• Nitrogen piping, valves and fittings (per required piping design)

Instructions

1. Connect the nitrogen piping to a nitrogen source. This source is usually a plant nitrogen header, self-generating unit or high-pressure cylinder. A block valve should be installed between the nitrogen source and the new piping for isolation purposes. Ensure this valve is closed until the procedure is complete.

2. Connect the nitrogen regulator to the new nitrogen piping. Connect new nitrogen piping to the outdoor storage tank. The regulator will control the pressure of the nitrogen to ensure it does not overpressure the storage tank.

3. Configure the nitrogen regulator to a pressure at or below the maximum allowable working pressure of the outdoor storage tank. This working pressure value will be available from the tank’s manufacturer.

4. Locate a vent valve for the storage tank. This should be a small valve on top of the tank that will allow the tank to breathe. Open this valve.

5. Open the nitrogen block valve and check the performance of the regulator. As the nitrogen flows into the tank, it will push the air/oxygen out of the tank through the open vent valve. After a sufficient amount of time (one hour), close the vent valve. The outdoor storage tank now has a nitrogen blanket.

References

• Crown Solutions: Nitrogen Blanket