UL-142 Modern RecTank

In the Spring of 2020, Modern Welding Company of Ohio received a purchase order for nine rectangular tanks intended for the use of backup power generation at the Philadelphia Metropolitan Children’s Cancer Hospital Cryogenics Laboratory. These tanks were all supposed to be built to a height of 132”.

Per UL 142, the maximum height of a rectangular tank is 103”. To exceed this height limitation, Modern would need to build a test tank that is representative of the tanks to be fabricated for our customers. Modern Welding Company of Owensboro offered to build the double wall rectangular test tank that would be subjected to two tests (top load and hydrostatic), witnessed by Underwriters Laboratories and the Steel Tank Institute.

Then on February 3, 2021, Modern Welding made history! The Owensboro plant tested the largest rectangular tank ever produced at a Modern Welding Company facility. The tank weighed approximately 30,000 lbs empty and 250,000 lbs filled with water. It was a double wall tank, fabricated out of 0.25” carbon steel. The dimensions were 12’ H x 12’ W x 24’ L, with a capacity of 26,500 gallons.

This hydrostatic tank test was conducted for the approval of a 12-foot-tall rectangular tank construction for Modern Welding, which would make us the only tank manufacturer in the United States authorized to build a rectangular tank with a height exceeding 103”.

The tank was subjected to a 15 psi hydrostatic test, which was the passing criteria for approval by Underwriters Laboratories. Once the 15 psi holding pressure was established, UL informed us that we had passed the test and are now authorized to build rectangular tanks up to a height of 14 feet.

Once we met the 15 psi approval pressure, we continued up to 30 psi—and the tank did not have any major failures!