by Lori Riddle

Today on the Think Tank we are Ammonia tank, API 620, low pressure tank, tank roof, air raising, insulated tanksharing a special storage tank project - an anhydrous ammonia storage tank in Beulah, ND. This project was completed in 2013, since then, it's the tank has been working hard for Dakota Gasification's award-winning Great Plains Synfuels plant. It is a unique tank, designed  to hold 30,000 tons of anhydrous ammonia, and equipped with a specially designed and constructed foundation. Storing anhydrous ammonia safely requires some pretty specific conditions - a low-pressure environment, and a steady low temp of -28 degrees Farenheit. Not your average tank conditions to be sure!

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This was an enormous tank, and a special part of the project was the huge roof. The roof was constructed on the tank bottom, inside the tank shell. When the roof was complete, the project team used air pressure to raise the tank up and put it into place at the top of the finished tank.

Check out the project details below, and don't miss the time lapse video of the tank roof being air raised into place!

Anhydrous Ammonia Storage Tank

API 620, low pressure tank, ammonia tank, ammonia storage, tank insulation, low temperature tank

Dakota Gasification Great Plains Synfuels Plant, Beulah, ND, API 620 Low Pressure Storage Tank

Dakota Gasification required additional anhydrous ammonia storage to supply the ground-breaking scrubber process at its ultra-clean Great Plains Synfuels Plant in Beulah, ND. The design, fabrication and construction the 30,000 ton ammonia storage tank presented a number of challenges – including potentially frigid temperatures in the forbidding North Dakota winter. The vast size of the storage tank, pressure requirements, temperature requirements and aesthetic requirements all promised a challenging project.

A Unique Tank Foundation

anhydrous ammonia tank, foam glass foundation, low temperature tankWorking with a skilled EPC team from Burns & McDonnell, Fisher Tank Company developed tank and foundation designs that would address the specific operational needs for the tank, the unique criteria for storing anhydrous ammonia, and the related environmental and safety concerns.

The tank is built on a slab foundation, with a base heating system, which prevents the soil under the foundation from freezing, and guards against damage to the slab from the extreme cold. In addition to the heating system, Fisher installed foam glass insulation between the tank bottom and the slab; this protects the slab from the very cold operating temperature of the tank itself.

Tank Construction Solutions

The extensive insulation system, required to maintain the -28 degrees Fahrenheit operating temperature, was installed after the exterior coating system was applied.

The single containment tank system also includes a vapor recovery system and an earthen dike around the tank foundation to ensure that all potential vapor emissions and liquid leakage will be fully contained.

air raising, tank roof, ammonia tank, wild lap roofFisher Tank Company designed the unique wild lap roof, and constructed, painted and insulated the roof on the ground inside the tank. Fisher air raised the completed roof into place. Once the roof was in place, the tank’s exterior insulation and the roof insulation were connected and sealed.

Tank Stats

170' diameter x 98' height

10,920,400 gallon capacity

API 620 Appendix R & API 625

-28 degrees Fahrenheit operating temperature

685 tons of steel

19,000 man-hours with zero safety incidents


Time lapse video - air raising an anhydrous ammonia tank roof:


API 620 Ammonia Tanks Ahydrous Ammonia

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