A Cylinder Doesn't Pass by Surviving. It Passes by Measuring.

Every high-pressure cylinder in service — on a ship, under an aircraft shelter, in a fire station — is living on a statutory clock. When its date comes up, the Gas Cylinder Rules require a periodic test, and that test is subtler than most people expect: the cylinder isn't asked merely to survive test pressure. It's asked to prove, by measurement, that it's still genuinely elastic. Neometrix's HP air bottle test and requalification facility is the complete six-station line that takes a service cylinder from arrival back to certified service: PLC shot blasting, machine de-valving, internal inspection, water-jacket hydrostatic testing where the actual verdict is measured permanent expansion, drying, revalving and recharge through a 600 bar-class booster train.

Holding Pressure Proves Nothing. Springing Back Does.

In the water-jacket method, the cylinder is sealed inside a water-filled jacket and pressurised internally. As it swells under pressure, it displaces jacket water — giving a direct reading of total volumetric expansion. Release the pressure, and whatever displacement doesn't come back is permanent expansion: plastic set, the unmistakable signature of metal that has stopped behaving elastically. Exceed the permitted percentage and the bottle is condemned — even if it held the test pressure without any complaint whatsoever.

The Rest of the Line Exists So This One Measurement Is Honest

Shot-blast first, because scale and old paint hide cracks from visual inspection, and the requalification stamp must be struck on genuinely bare metal. De-valve by machine, because a valve removed with a pipe wrench and refitted by feel is exactly how threads and necks get ruined over repeated cycles. Dry thoroughly, because water left inside a breathing-air bottle is corrosion running on a schedule. Then revalve, recharge, stamp, and rack — each step closing a door that would otherwise compromise the final measurement's honesty.

Six Stations, One Verdict

PLC-controlled shot blasting, machine de-valving, internal inspection, a water-jacket hydro bed with its own power pack, drying and revalving, and recharge through a booster train with an automatic cutoff set at 605 bar — plus storage racks and nitrogen sets, all installed, cabled, earthed and commissioned at the yard as one complete working facility, not a collection of separate machines.

Built for Gas Cylinder Rules 2014

The Rules fix the periodicity, the test method, and the record-keeping requirements — but the station's own recognition is what actually makes its stamps mean anything to a regulator or an end user. Technical support and consultancy for CCOE approval is explicitly carried in the scope of supply — support for approval, never approval claimed in advance of the actual process.

Where Requalification Actually Fails

Rarely at the pump itself. It fails at the bookkeeping of truth: a bottle tested through paint that hid a gouge underneath; a valve refitted with damaged threads that weeps slowly for years afterward; water left inside because drying was rushed to meet a schedule; an expansion reading taken on a jacket that was never properly calibrated in the first place. The facility is built as a complete line rather than a single pump in a corner precisely because each station closes one of those specific failure doors.

Frequently Asked Questions

Why does a high-pressure cylinder need to demonstrate "permanent expansion" rather than just surviving the test pressure?
Because simply surviving a pressure test tells you almost nothing about a cylinder's remaining structural integrity -- a cylinder that's developed dangerous metal fatigue can still hold a single test pressure without visibly failing. What actually matters is whether the cylinder is still behaving elastically, meaning it returns to close to its original size after the pressure is released. In the water-jacket method, the cylinder is sealed in a water-filled jacket and pressurized; as it expands, it displaces a measurable volume of water. After the pressure is released, whatever expansion doesn't reverse is "permanent expansion" -- a direct, measured sign that the metal has begun to yield plastically rather than flexing elastically. If that permanent expansion exceeds a specified percentage, the cylinder is condemned and removed from service, regardless of whether it technically survived the applied pressure.

Why does the shot blasting step matter for a pressure test, rather than just being about appearance?
Because scale, rust, and old paint on a cylinder's surface can physically hide cracks, gouges, or corrosion pitting that a visual inspector needs to be able to see clearly to do their job properly. If a cylinder is inspected while still covered in old surface coating, a genuine defect underneath that coating can go completely undetected -- and that cylinder could then be certified as safe when it actually isn't. Shot blasting strips the cylinder down to bare metal specifically so that inspection has an honest, unobstructed surface to examine, and so that any requalification stamp gets struck onto clean steel rather than onto old paint or scale that could eventually flake off, taking the stamp's legibility with it.

Get In Touch

For full specifications, RFQs, or a technical discussion about the HP air bottle test and requalification facility:

• Product page: HP Air Bottle Test Facility
• Email: [email protected]
• Phone: +91-7777-876-876