Hydrostatic Testing Explained
Hydrostatic testing (a form of pressure testing) is one way a cylinder is revalidated for continued service. Here is what it involves.
In practice
Proven before it is filled
Pressure testing confirms the cylinder wall can still safely hold its working pressure before it carries gas again.
Backed by inspection
A pass is paired with a visual and valve check, so strength and condition are confirmed together.
What a hydrostatic test does
In a hydrostatic test the cylinder is filled with water and pressurised to a defined test pressure above its working pressure. The test checks the cylinder does not leak and does not expand beyond an acceptable permanent set — confirming the metal still has the strength to be safely filled.
- Measures expansion under pressure and any permanent deformation.
- Combined with a visual/internal inspection and valve check.
- Passing cylinders are dried, re-stamped with a new test date and returned to service.
Whether a cylinder needs hydrostatic testing depends on its type and standard — always follow the markings and current regulations.
The checks that go with it
A pressure test never stands on its own. Revalidation pairs it with the condition checks that catch problems a pressure reading alone would miss, so strength and soundness are confirmed together.
- Internal and external visual inspection for corrosion and damage.
- Valve removal, inspection and correct re-fitting.
- Drying, then re-stamping with the new test date on a pass.
How a cylinder is pressure-tested
The cylinder is filled with water, sealed and raised to a test pressure above its normal working pressure. Technicians watch for leaks and measure how much the cylinder expands — and whether it springs back. A cylinder that holds pressure and returns to size passes; one that does not is withdrawn from service.
Getting a cylinder back in test
Check the stamp
Bring the cylinder in or ask at refill — we read the stamped test date to see whether it is still in test or due for revalidation.
Inspect and revalidate
If it is out of test we arrange the periodic inspection and any testing the cylinder needs, carried out to current UK requirements.
Re-stamp and return to use
A cylinder that passes is re-stamped with a new test date and put back into service, so it can be filled again. One that fails is withdrawn.
Frequently asked questions
What is a hydrostatic test?
A pressure test using water to confirm a cylinder can safely hold its working pressure before being returned to service.
Does every cylinder need a hydrostatic test?
Not necessarily — the test method depends on the cylinder type and standard. Some are revalidated by other approved methods. Always follow the cylinder markings and current regulations.
What happens if a cylinder fails?
It is withdrawn from service rather than returned to use. A failed cylinder is not refilled.
Do I have to arrange testing myself?
No — if your Adams Gas cylinder is due, we can arrange revalidation alongside your refill so it is one job, not two trips.
Not sure if your cylinder is in test?
We check every cylinder before filling, and can arrange retesting if it is out of date. Talk to our team.