Compressed Gas Safety: Cylinder Storage, Handling Rules, and What OSHA Requires

A standard compressed oxygen cylinder holds gas at around 2,200 psi. If the valve snaps off, that pressure turns the cylinder into an unguided projectile capable of punching through concrete block walls. This isn’t a theoretical scenario. OSHA and the Compressed Gas Association (CGA) document incidents involving what they call “rocket cylinders,” and the results are catastrophic.

That’s the hazard at the extreme end. But compressed gas cylinders on job sites and in facilities create several categories of risk, and most incidents don’t come from dramatic valve failures. They come from slow leaks, improper storage, wrong gas used with the wrong equipment, and workers who were never trained on what the labels and markings actually mean.

OSHA’s Requirements Under 1910.101

The primary general industry standard for compressed gas is OSHA 1910.101. It’s relatively short but important: it requires that employers handle, store, and use compressed gas cylinders in accordance with Compressed Gas Association (CGA) pamphlet P-1, “Safe Handling of Compressed Gases in Containers.”

OSHA doesn’t reprint the entire CGA standard inside 1910.101. It incorporates it by reference. That means CGA P-1 has the force of OSHA regulation, and inspectors can cite violations based on CGA P-1 requirements.

For welding and cutting gases specifically, OSHA 1910.253 adds more detailed requirements for oxygen-fuel gas welding, covering cylinder storage, manifold systems, and regulator requirements. If your facility uses acetylene and oxygen for hot work, you need both 1910.101 and 1910.253.

For construction, the relevant standard is 29 CFR 1926.350. The requirements are similar in substance but under a different part of the CFR.

If you’re building or reviewing a compressed gas program, read 1910.101 and CGA P-1 together. Don’t rely on summaries, including this one.

Cylinder Markings: What They Mean

Every compressed gas cylinder has markings that tell you critical information. Knowing how to read them is a basic competency for anyone who works around these cylinders.

DOT markings on the shoulder of the cylinder identify the specification under which the cylinder was manufactured. Markings like “DOT 3AA” or “DOT 3AL” tell you the material (steel vs. aluminum) and the construction method. This matters for hydrostatic testing intervals.

The service pressure is stamped on the cylinder, typically in psi. This is the working pressure the cylinder is rated for at 70 degrees Fahrenheit.

The hydrostatic test date is also stamped on the cylinder. This is the month and year of the last required pressure test. For most steel cylinders under DOT 3AA, the test interval is 5 or 10 years depending on the marking. Cylinders past their test date cannot be refilled and should be taken out of service.

CGA inlet connection fittings are standardized by gas type to prevent connecting the wrong regulator to the wrong cylinder. Acetylene uses CGA 510 or 300 fittings. Oxygen uses CGA 540. Industrial nitrogen uses CGA 580. The threads are intentionally different for incompatible gases, and you should never force a fitting or use adapters to make a connection work. If the fitting doesn’t mate cleanly, the wrong regulator is on the wrong cylinder.

Color coding is common but not standardized in the United States. CGA publishes recommended color codes, but they aren’t OSHA-mandated. Don’t rely on color alone to identify gas type. Read the label.

Storage Requirements

Upright and secured. That’s the baseline for all compressed gas cylinder storage, and it’s where most facility violations start.

Cylinders must be stored upright (valve end up) and secured with a chain, strap, bracket, or other restraint that prevents tipping. A cylinder leaning against a wall isn’t secured. A cylinder in a stand without a chain isn’t secured. One bump from a forklift can knock an unsecured cylinder over and shear the valve.

Valve protection caps must be in place on all cylinders not actively in use. This means cylinders in storage, cylinders being transported, and cylinders staged but not connected. The cap protects the valve from damage and prevents the rocket cylinder scenario.

Cylinders must be stored away from heat sources. Stored cylinders should not be in areas where temperatures regularly exceed 125 degrees Fahrenheit, because heat increases internal pressure.

Full and empty cylinders must be stored separately and clearly labeled. “Empty” is a relative term for cylinders that still have residual pressure, but the separation requirement prevents full cylinders from being confused with depleted ones and vice versa.

The most frequently cited storage violation involves oxygen and fuel gas separation. OSHA 1910.253(b)(4)(iii) requires oxygen cylinders in storage to be separated from fuel gas cylinders, such as acetylene, propane, or hydrogen, by at least 20 feet of open space. If 20 feet isn’t available, a noncombustible barrier at least 5 feet high with a fire-resistance rating of 30 minutes or more satisfies the requirement.

This 20-foot rule exists because oxygen dramatically accelerates combustion. A fuel gas leak near an oxygen cylinder creates conditions for a fire or explosion far faster than a fuel gas leak alone. Keep them apart.

For any work involving hot work permits and welding gas management, see the hot work permit guide.

Handling and Transport

Never roll a compressed gas cylinder on its side to move it. Use a cylinder cart with a chain to secure the cylinder in the upright position. Cylinders moved without carts should be tilted slightly and walked on the bottom edge. Even that method is second-best.

Never use a cylinder’s valve as a handle. Valves are not designed to bear the lateral stress of the cylinder’s weight, and a damaged valve creates an immediate hazard.

Keep valve protection caps on during all transport. Remove the cap only when the cylinder is secured in place and you’re ready to attach a regulator.

Don’t use lifting magnets, hooks through the valve guard, or other improvised lifting methods. Cylinders moved by crane or hoist require a proper cylinder cradle or cage.

Don’t use compressed gas to blow dust off clothing or skin. High-pressure gas injected into the skin causes an air embolism, which is a medical emergency. This applies to all compressed gases including compressed air.

Regulator Requirements and Safety

The regulator reduces cylinder pressure to a usable working pressure. It also represents one of the most common points of failure if the wrong regulator is installed or if maintenance is deferred.

Never use oil or grease on oxygen regulators or fittings. Oxygen under pressure can cause petroleum-based lubricants to ignite spontaneously. Use oxygen-compatible lubricants only if any lubrication is needed at all.

Inspect regulators before each use. Look for damaged gauges, cracked hoses, and worn connections. A regulator with a damaged gauge is a problem because you can’t verify the working pressure you’re delivering.

Open cylinder valves slowly when attaching a regulator to a system. Rapid pressurization of the regulator can cause adiabatic compression, where the rapid increase in pressure generates enough heat to ignite combustible materials downstream. This is called “dieseling” in oxygen systems, and it’s a known failure mode.

For acetylene, use only regulators rated for acetylene service. Acetylene regulators are designed to manage the unique behavior of acetylene dissolved in acetone, and they’re built to limit delivery pressure to safe working levels.

Acetylene: Different Rules for a Different Gas

Acetylene isn’t stored as a pure compressed gas the way nitrogen or oxygen is. It’s dissolved in acetone, which is absorbed into a porous material inside the cylinder. The acetylene is released from the acetone as you draw from the cylinder.

This has practical consequences. The maximum safe delivery pressure for acetylene is 15 psig. Above 15 psig, acetylene becomes unstable and can decompose explosively, even without a flame. This is why acetylene regulators are designed to limit outlet pressure. And it’s why you should never open an acetylene cylinder valve fully, only one and a half turns maximum, so the valve can be closed quickly in an emergency.

Acetylene cylinders must always be stored and used upright. If an acetylene cylinder has been stored on its side, stand it upright for at least one hour before use to let the acetone resettle into the porous filler. Using an acetylene cylinder that’s been on its side risks drawing acetone liquid into the regulator and hose, which contaminates downstream equipment and can cause flashback.

Acetylene’s flammable range in air runs from 2.5% to 100%. That’s the widest flammable range of any common industrial gas. A small leak is enough to create an explosive atmosphere in a confined or poorly ventilated space.

Flashback arrestors are a required engineering control for acetylene torch and regulator systems. A flashback is when a flame travels backward through the hose toward the cylinder. Without an arrestor, a flashback can rupture the hose, damage the regulator, or reach the cylinder. Flashback arrestors install at the regulator outlet and at the torch body.

Inspection, Testing, and Taking Cylinders Out of Service

Visual inspection before each use is the minimum standard. Check for corrosion, dents, bulges, arc strikes (which indicate someone used the cylinder as a ground in a welding circuit), and legible labels. A cylinder with arc strikes should not be returned to service without evaluation by the supplier. Arc strikes can create weak points in the cylinder wall.

Hydrostatic testing is the periodic pressure test required by DOT to verify cylinder integrity. For most steel cylinders, the interval is 5 years. Cylinders with the “+” mark after the test date can be filled to 10 percent over service pressure. Cylinders marked with a star may have a 10-year test interval.

Cylinders past their hydrostatic test date cannot legally be refilled. Return them to the supplier.

Empty cylinders aren’t truly empty. They retain residual gas pressure. Store them separately from full cylinders, label them as empty, and keep the valve caps on. Return them to the supplier for refilling.

For the full chemical hazard and SDS documentation picture, see the GHS SDS guide. For PPE requirements when handling oxidizers and flammable gases, see the PPE guide. And make sure your emergency action plan covers cylinder leak and fire scenarios before you need it.

The most common compressed gas citations from OSHA inspections are unsecured cylinders, missing valve caps, and improper oxygen-fuel gas separation. Those three violations are also among the easiest to correct. Walk your storage area today and check for all three.