Frequently Asked Questions



What Is Hydrostatic Testing?

Hydrostatic testing uses high pressure water to check your cylinder's structural integrity through subjecting it to stress and discovering possible permanent expansion or overexpansion of the tank walls, indicating unsafe structural deficiencies. All testing is done within a water jacket to ensure safety in the event of catastrophic tank failure.


How often do my tanks need to be tested?

Inspection intervals vary by cylinder type, manufacturer, application and frequency of use. The following list highlights some general limits based on DOT published requirements:


  • SCUBA Tanks Marked 3AL (Every 5 years – No Life Limit) Visual Eddy Current  MFG before Jan 1980

  • Oxygen Bottles Marked DOT 3AA & 3AL (Every 5 years - No Life Limit)

  • Oxygen Bottles Marked DOT 3HT (Every 3 Years - 24 Year Life Limit)

  • Composite Oxygen Bottles (Every 3 or 5 Years - 15 Year Life Limit)


Why is hydrostatic testing necessary?

Pressurized tanks are regulated by the Department of Transportation. They require testing to reduce the probability of injury caused by catastrophic failure.  Every tank must pass an initial DOT certification, visual inspection, and hydrostatic test prior to being sold, and before being filled.


Will it take a long time to hydro-test my tank?

 While the actual hydrostatic test takes only a few minutes, the set-up, visual inspection, eddy current testing and drying add time to the complete process.


What are the common reasons for tank failure?

Common issues involve physical damage, heat exposure, weak thread valves, degradation in structural integrity and internal/external corrosion.


If my tank fails, can I still use it?

DOT regulations state that a tank that fails during hydrostatic testing cannot be filled again. The cylinder threads are scored so that it cannot be filled again and the serial number will be stamped out. 




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