Scuba Cylinder Care and Maintenance: Keeping Your Air Safe and Your Tank Legal

Paul Lenharr II   Dec 20, 2025

Scuba Cylinder Care and Maintenance: Keeping Your Air Safe and Your Tank Legal

Your scuba cylinder is the one piece of equipment that holds the thing you absolutely cannot dive without: breathable gas under pressure.

And yet, cylinders are often the most misunderstood—and most neglected—pieces of scuba gear. Proper care isn’t complicated, but it is essential. It affects safety, fill station acceptance, and how long your tank will last.

Understanding the basics of cylinder maintenance keeps your dives safer and prevents unpleasant surprises when you show up to dive.

Why Cylinder Maintenance Matters

Scuba cylinders are pressure vessels. They’re built to be incredibly strong, but they rely on proper inspection and handling to stay that way.

Neglect can lead to:

• internal corrosion

• compromised structural integrity

• contaminated breathing gas

• refused fills

• unsafe diving conditions

Good maintenance isn’t about being cautious—it’s about respecting physics and regulations.

Annual Visual Inspections (VIP)

Every scuba cylinder must undergo a visual inspection once per year.

This inspection checks for:

• internal corrosion or contamination

• external damage (dents, gouges, cracks)

• neck and thread condition

• valve condition and function

• proper markings and compliance

A visual inspection is performed by a trained technician and includes removing the valve to inspect the inside of the tank. Even a cylinder that “looks fine” on the outside can fail internally.

If your tank doesn’t have a current visual inspection sticker, most fill stations will refuse to fill it—no exceptions.

Hydrostatic Testing Every 5 Years (DOT Requirement)

In the United States, the Department of Transportation (DOT) requires scuba cylinders to undergo hydrostatic testing every five years.

Hydrostatic testing:

• measures how much the cylinder expands under pressure

• confirms it returns to its original size safely

• verifies the metal has not fatigued beyond safe limits

During the test, the tank is filled with water and pressurized well beyond normal operating pressure. If it passes, it’s stamped with a new hydro date.

If it fails, the tank is permanently removed from service.

This test isn’t optional—it’s a federal requirement for transporting and filling compressed gas cylinders.

Storage: The Small Habits That Matter

How you store your cylinder between dives makes a big difference.

Best practices include:

• storing with a small amount of pressure inside (never empty)

• keeping cylinders dry and out of standing water

• avoiding prolonged heat exposure

• securing tanks so they can’t fall or roll

• Fresh water rinse the entire tank but ESPECIALLY the valve after being in brackish, chlorinated, or salt water. Make sure to get fresh water in and behind the hand wheel.

Moisture is the enemy. A completely empty tank can draw in humid air, leading to internal corrosion that isn’t visible until inspection.

Transporting Cylinders Safely

Transport damage is more common than dive damage.

When transporting tanks:

• secure them to prevent rolling

• avoid resting weight on valves

• never lift a tank by the valve

• keep protective caps or boots in good condition

Valve damage can render an otherwise perfect cylinder unsafe.

Aluminum vs. Steel Considerations

Both aluminum and steel cylinders are safe when properly maintained—but they age differently.

Aluminum tanks:

• are more resistant to rust

• can suffer from cracking if neglected

• are sensitive to certain manufacturing dates

Steel tanks:

• are stronger and smaller for the same gas volume

• require extra attention to moisture control

• can last decades with proper care

Knowing what material you own helps guide good storage and inspection habits.

When a Cylinder Should Be Retired

Not every tank lasts forever.

Cylinders should be removed from service if they:

• fail hydrostatic testing

• show significant corrosion or cracking

• have damaged threads or necks

• have been involved in serious impact

Retiring a tank is a safety decision—not a loss. No dive is worth gambling with compromised equipment.

The Bottom Line

Scuba cylinder care isn’t complicated—but it is non-negotiable.

Annual visual inspections keep problems from developing quietly.
Five-year hydrostatic testing ensures the tank remains structurally sound.
Good storage and handling habits extend lifespan and protect your safety.

Your tank doesn’t just hold air.
It holds trust—earned through maintenance.