What is Hydrostatic Testing?
Hydrostatic testing, commonly called hydrotesting, is a safety test used to verify that a high-pressure cylinder can safely hold gas under pressure. Over time, cylinders are exposed to wear, corrosion, and stress that are not always visible from the outside. Hydrotesting confirms the structural integrity of the cylinder and ensures it meets DOT safety requirements before it is returned to service.
This test is required at regular intervals for cylinders used for breathing air, oxygen, COâ‚‚, and other compressed gases.
How the Hydrotesting Process Works
1. Visual Inspection
2. Valve Removal
3. Water Filling
4. Pressurization
5. Expansion Check
6. Evaluation
7. Drying and Marking
The cylinder is checked for visible damage or corrosion.
The valve is removed to allow testing and internal access.
The cylinder is filled with water for safe testing.
Expansion is measured to confirm the cylinder remains within safe limits.
Test results are reviewed to determine pass or fail status.
Approved cylinders are dried, stamped, and certified for service.
The cylinder is pressurized above its working pressure using DOT-approved equipment.
Why Hydrotesting Matters​​
Hydrostatic testing helps prevent cylinder failures, protects users and equipment, and ensures compliance with federal regulations. It is a critical step in maintaining safety for divers, firefighters, medical facilities, and industrial users alike.
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At Alpha Cylinders, every test is performed with precision, transparency, and full regulatory compliance—so you can trust the safety of every cylinder returned to service.