WHAT WE DO
DOT-Required Hydrostatic Testing for SCUBA Cylinders
Every SCUBA cylinder is a federally regulated pressure vessel under DOT 49 CFR Part 180. Steel and aluminum SCUBA cylinders must be hydrostatic tested every 5 years. A cylinder past its test date cannot legally be filled at any dive shop or fill station in the U.S. — no exceptions, no grace periods.
Hydrostatic testing is not optional and not just paperwork. Over time, even well-maintained cylinders develop metal fatigue, internal corrosion, and micro-fractures invisible to the naked eye. Under 5,000 psi of test pressure, those defects reveal themselves. That's the entire point — finding them before a fill, not during one.
We use the water jacket volumetric expansion method — the only DOT-approved test method for steel and aluminum cylinders. Every test is performed in-house by our certified technicians. Every passing cylinder gets a DOT stamp (month/year + RIN D133) and written test documentation.
What Happens If a Cylinder Fails?
Per DOT regulations, we are legally required to permanently condemn any cylinder that fails — typically by cutting or drilling. We document every failure and never return a failed cylinder as serviceable. This is non-negotiable regardless of how much the cylinder cost or how new it looks.
Your cylinder must pass DOT testing before any legal fill
TESTING PROCESS
How We Test Your SCUBA Cylinders
Every step follows DOT 49 CFR Part 180 exactly. Performed entirely in-house at our St. Petersburg facility — nothing sent out.
Full Visual Inspection
Every cylinder is visually inspected inside and out before any pressure is applied. Exterior checks: dents, gouges, cuts, corrosion, neck damage. Interior: we use an inspection light to check for pitting, corrosion, and thread integrity. Valve removed, inspected, serviced or replaced. Cylinders with disqualifying structural damage are condemned here — before the test even starts.
Water Jacket Pressurization
The cylinder is placed inside a sealed water jacket and pressurized to 5/3 of rated service pressure using hydraulic equipment. A standard 3000 psi aluminum SCUBA tank is tested to 5000 psi. Pressure is held for a minimum of 30 seconds. The water jacket contains any potential failure safely — the cylinder cannot blow outward during the test.
Volumetric Expansion Measurement
Under pressure, the cylinder expands and displaces water — this is total expansion. When pressure is released, the cylinder must return to near its original size. The portion that doesn't return is permanent expansion. DOT requires permanent expansion to be under 10% of total expansion. Exceeding 10% means the metal has fatigued beyond safe limits — cylinder is condemned, period.
DOT Stamp + Documentation
Every passing cylinder is stamped: test month, test year, and RIN D133 — our federal identification number. This stamp is permanent, visible on the cylinder, and verifiable through DOT records. You also receive written test records for each cylinder. Those records matter for your insurance, dive shop compliance inspections, and any future cylinder history questions.
THE FEDERAL STANDARD
49 CFR Part 180 — Cylinder Requalification
Steel and aluminum SCUBA cylinders: retest every 5 years. Only DOT-authorized facilities with an active RIN number may perform requalification testing. Cylinders with unknown test history must be tested before refilling.
Call to Schedule → (727) 620-3473TESTING INTERVALS
SCUBA Cylinder Types and Testing Requirements
Check the stamp on your cylinder. Not sure what type you have? Call us — we identify it for free.
| Cylinder Type | Material | Service Pressure | Test Interval | Service Life |
|---|---|---|---|---|
| Standard Steel SCUBA (80–100 cu ft) | Carbon steel | 2250–3000 psi | Every 5 Years | Indefinite if passing |
| Aluminum SCUBA (Luxfer, Catalina) | 6061 aluminum | 3000 psi | Every 5 Years | Indefinite if passing |
| High-Pressure Steel (HP100, HP120) | High-tensile steel | 3442–3500 psi | Every 5 Years | Indefinite if passing |
| Pony / Stage / Bailout Bottles | Aluminum or steel | 3000 psi | Every 5 Years | Indefinite if passing |
| Rebreather Cylinders (O₂, Diluent) | Aluminum or steel | 3000 psi | Every 5 Years | Per manufacturer |
| HPA / Paintball / Airsoft | Al. or carbon fiber | 3000–4500 psi | Every 3–5 Years | 15 yrs (composite) |
Per DOT 49 CFR Part 180 · Call us if you are unsure about your cylinder type or test history
PRICING
How Much Does SCUBA Cylinder Testing Cost?
Pricing varies by cylinder type, quantity, and any valve service work needed. We do not publish a flat-rate price list because every order is a little different — a 6 cu ft pony bottle and an HP120 are not the same job.
Individual Tanks
Call or email for current pricing. Single cylinders and small quantities welcome — no minimum order.
Dive Shop Fleets
Volume pricing available for shops managing rental fleets. Contact us for a quote on your inventory size.
Commercial & Military
Large fleet contracts and recurring service agreements available. We work around your operational schedule.
Get a price on your cylinders in 2 minutes
Call during business hours or send us a quick email with your cylinder type and quantity.
25+
Years in Business
100%
In-House Testing
D133
DOT RIN
1999
Founded
WHY CHOOSE US
Why Divers and Dive Shops Choose Us Over Anyone Else
Most companies that advertise hydrostatic testing do not do it themselves. They box your tanks and ship them to a third party — adding time, cost, and an unknown facility into the chain. We hold our own DOT RIN (D133). We test in-house. We stamp our own cylinders. There is no middleman.
Everything Done In Our Facility
No subcontractors. No third-party labs. No mystery. Your cylinder goes into our test equipment and comes back with our stamp. You know exactly who did the work.
Fast — Days, Not Weeks
In-house means we set our own schedule. Most orders done in days. Walk-in service available for small quantities with same-day or next-day turnaround in many cases.
Documentation That Actually Holds Up
DOT stamp on every passing cylinder. Written test records provided. Essential for annual dive shop compliance inspections, insurance audits, and military chain-of-custody requirements.
We Test Every Cylinder Type
Steel, aluminum, pony bottles, stage tanks, rebreather cylinders, HPA bottles. If it holds high-pressure gas and needs DOT requalification, we test it. Unusual spec? Call us first.
WHO WE SERVE
From One Tank to a Fleet of 500
We handle all quantities with the same documentation standards and turnaround commitment — whether you're a recreational diver with two tanks or a dive shop with 300 rentals.
Dive Shops
Rental fleet compliance, volume pricing, recurring schedules. We keep your inventory current so you never fail an inspection or have to turn a customer away.
Commercial Divers
Underwater construction, salvage, inspection, and pipeline work. All cylinder configurations tested including stages, bailouts, and rebreather cylinders. Full OSHA documentation.
Military & LEO
EOD, combat swimmers, tactical dive units. Full chain-of-custody documentation. We understand operational timelines and communicate clearly throughout the process.
Recreational Divers
Drop off at our St. Pete facility or ship from anywhere in the U.S. We return cylinders promptly with the DOT stamp and full written documentation.
Industrial & Scientific
Research vessels, aquariums, marine science, underwater inspection contractors. All compressed air and specialty gas cylinder sizes. We work around your schedule.
HPA / Paintball
Same DOT requirements as SCUBA. We test aluminum and carbon fiber composite HPA bottles. Composite cylinders have a 15-year service life from manufacture — we will not test an expired composite.
SHIPPING AND DROP-OFF
Send Your Tanks from Anywhere in the U.S.
We accept SCUBA cylinders by UPS, FedEx, or LTL freight from across Florida and the continental U.S. Call us before shipping — DOT hazmat regs require specific packaging for empty cylinders, and we need to confirm our current shipping address. Improperly packaged cylinders will be refused by carriers.
Before You Ship — Quick Checklist
CREDENTIALS AND AUTHORIZATIONS
Federally Authorized. State Licensed. Fully Verified.
SCUBA cylinder hydrostatic testing is federally regulated. Every credential below is current, independently verifiable, and directly relevant to the safety of your cylinders.
FEDERAL AUTHORIZATION
DOT Requalification — RIN D133
Direct U.S. DOT authorization under 49 CFR Part 180 to perform hydrostatic requalification testing on compressed gas cylinders. RIN D133 is stamped on every cylinder we test and is permanently verifiable through federal DOT records. Authorization valid through November 22, 2027.
Verify Our Authorization →STATE LICENSING
Florida Fire Marshal Licensed
Class 01 — Fire Extinguisher Dealer · License #585272-0007-2005
Class 04 — Pre-Engineered Systems Dealer · License #292428-0001-1993
Both licenses valid through December 31, 2027
EXPERIENCE AND INDUSTRY
100+ Years Combined Experience
In St. Petersburg since 1999. All technicians receive ongoing DOT hazmat training per 49 CFR §172.704. This is our specialty — not a side service. We have been testing compressed gas cylinders longer than most of our competitors have existed.
COMMON QUESTIONS
Frequently Asked Questions
Straight answers from our certified technicians — no fluff.
Steel and aluminum SCUBA cylinders must be tested every 5 years under DOT 49 CFR Part 180. The test date is stamped directly on the cylinder — look for a format like "10 23 D133," meaning October 2023 tested by RIN D133 (us). A tank past its test date cannot legally be filled at any dive shop or fill station in the U.S., full stop. No grace period exists under federal law.
We use the water jacket volumetric expansion method. The cylinder is pressurized to 5/3 of its service pressure inside a sealed water jacket. We measure total expansion (volume displaced under pressure) and permanent expansion (volume that doesn't return after pressure release). If permanent expansion exceeds 10% of total expansion, the metal has fatigued beyond safe limits and the cylinder must be condemned. We also do a full visual inspection — exterior corrosion, interior pitting, neck cracks, thread damage.
Yes — we accept cylinders from across Florida and the continental U.S. via UPS, FedEx, or LTL freight. Call us at (727) 620-3473 before shipping. Empty cylinders are DOT hazmat items with specific packaging requirements. Valves must be removed or secured open, cylinders must be in DOT-approved packaging, and we need to confirm our current shipping address. Improperly packaged shipments get refused by carriers. Call first and we'll walk you through exactly what to do.
A failed cylinder cannot be returned to service. We are legally required to permanently condemn it — typically by drilling or cutting to render it incapable of holding pressure. We document the failure thoroughly, specify the reason, and notify you. We never return a failed cylinder as serviceable and never pass a marginal one to avoid an awkward conversation. The condemnation documentation matters for insurance purposes.
Yes — we test all standard SCUBA configurations including pony/bailout tanks (6–40 cu ft), stage bottles, and rebreather O₂ and diluent cylinders. DIN and yoke valve configurations both accepted. If you have an unusual cylinder or specialty spec, call before shipping to confirm compatibility and testing requirements.
Yes — HPA cylinders for paintball and airsoft are subject to the same DOT testing requirements as SCUBA tanks. We test aluminum and carbon fiber composite HPA bottles. Important note on composites: they have a 15-year manufacturer service life from the date stamped on the cylinder. After that date, they cannot be retested or returned to service regardless of condition. We will not test an expired composite — this is a federal requirement, not a policy we can waive.
Because everything is done in-house, we set our own schedule. Most orders complete in days, not weeks. Walk-in customers with 1–4 cylinders are often served same-day or next-day during business hours. Larger batches from dive shops and commercial operators should be scheduled in advance — call or email to discuss logistics and get a realistic turnaround estimate based on current volume.
Pricing varies by cylinder type, quantity, and any valve service needed. We don't publish a flat-rate price list because a single pony bottle and a batch of HP120s aren't the same job. The fastest way to get a price is to call us at (727) 620-3473 or email info@servicedfireequipment.com with your cylinder type and quantity — we'll get you a number quickly. Volume pricing is available for dive shops and commercial operators.