For a DOT 3HT oxygen cylinder to be eligible for recharging, when must it have been hydrostatically tested?

A DOT 3HT oxygen cylinder must undergo hydrostatic testing every 3 years to be eligible for recharging. This testing is a safety requirement designed to ensure that the cylinder can safely hold high-pressure gas without leaking or rupturing. The frequency of testing is outlined in the regulations imposed by the Department of Transportation (DOT).

These regulations are based on the material properties and the design of the cylinder, specifically for those classified under the DOT 3HT specification, which are made from heat-treated high-strength steel. The 3-year interval for hydrostatic testing helps to ensure ongoing compliance with safety standards, thereby protecting users and reducing the risk of accidents due to cylinder failure.

While other intervals exist for different types of cylinders or may apply under other scenarios, the specific requirement for DOT 3HT cylinders is every 3 years, making it crucial for operators and maintenance personnel to be aware of this testing schedule to ensure safe operation and legal compliance.