SCUBA Tank Testing Requirements

Testing scuba tanks is an important part of diver safety. Scuba tanks are pressurized vessels and the average scuba tank when filled to 3,000 pounds per square inch, or psi, has about 1.3 million foot-pounds of kinetic energy potential, which is an explosive power equivalent to a hand grenade, according to The Scuba Guide. Each country sets its own rules for testing scuba tanks. In the United States, the Department of Transportation sets the requirements and guidelines for testing tanks.

  1. Pressure Testing

    • U.S. Department of Transportation rules require hydrostatic testing of all scuba tanks every five years by companies licensed to perform these tests. The testing uses special equipment to ensure that the tank has proper levels of both elastic and permanent expansion underwater and under pressure. The tank is pressurized for the test. The hydrostatic test also ensures that the tank does not leak or have any other flaws. Cylinders made of aluminum alloy are also tested to ensure they do not crack. The hydrostatic test ensures that the tank can hold the proper amount of pressure underwater and also ensures that the tank will not explode, according to Underwater Diving Equipment. Technicians condemn any tank that fails the test.

    Visual Check

    • Some tanks are made of aluminum and some are made of steel. Steel is stronger than aluminum. Therefore, its walls do not have to be as thick as an aluminum tank of the same dimensions to have the same maximum pressure ratings. This means the steel tank has a larger interior volume and holds more air than the same size aluminum tank. However, steel is prone to rust and if iron oxide flakes off then more rusting can occur at the same sight and weaken the steel tank. If aluminum rusts, it forms aluminum oxide, which stays in place and protects the tank, according to Deep-Six Underwater Systems, Inc.

      U.S. Department of Transportation rules require an annual visual inspection of all scuba tanks. At that time, inspectors check for any dents or for signs of rust or any other damage on the exterior or interior of the tank, as well as on the valve.

    Inspection Labels

    • The U.S. Department of Transportation also requires all tanks to have inspection labels proving that they have been tested and passed the tests. If you rent a tank, check the labels and make sure it is up to date on testing. The technician who performs the hydrostatic test will place a label on the neck of the tank stating the month, testing station federal identification number and the year the tank was tested and passed the test. The law requires tanks to undergo and pass hydrostatic tests every five years. Tanks must undergo a visual inspection every year and inspectors place an evidence-of-inspection sticker on the tank with the month and year stated on the label.

      If the hydrostatic test date was more than five years ago, or if the visual inspection was more than one year ago, it is a violation of federal law for a dive shop to fill the tank. There are federal fines for filling a tank that is overdue for inspection or testing, along with fines for transporting a pressurized scuba tank that does not have a current hydrostatic inspection date.