Cylinder inspection and testing: what each country and body requires.

Two kinds of check

The sources describe two broad checks. A requalification or periodic inspection and test includes a pressure (hydrostatic or hydraulic) test. A visual inspection is a check without a pressure test. Some aluminium cylinders also get an eddy current examination for cracking at the neck. Each country sets its own intervals for these, and they do not match.

At a glance

United States: 49 CFR 180.209

The federal rule, 49 CFR 180.209 (current text as published by Cornell's Legal Information Institute), sets requalification intervals in its Table 1:

• DOT 3AL (aluminium): a test at a minimum of five-thirds of service pressure every 5 years. The table's 12-year option applies only to fire-extinguisher service, not to scuba.
• DOT 3AA (steel): the same test pressure, with periods of 5, 10 or 12 years depending on conditions. The 10-year option requires, among other conditions, that the cylinder is not used for underwater breathing.

Paragraph (m) adds a further check for DOT-3AL cylinders made of 6351-T6 aluminium in scuba, breathing-apparatus or oxygen service: every 5 years, an eddy current examination combined with a visual inspection, on top of normal requalification. Cylinders with cracking that reaches the neck threads as the rule defines it are condemned.

Luxfer, the cylinder maker, in an undated FAQ, summarises the federal position as requiring every aluminium scuba cylinder to be hydrostatically retested and visually inspected every five years, whatever its alloy.

The annual visual inspection: practice or requirement?

The federal rule text does not set an annual visual inspection for scuba cylinders, and its option to use a visual inspection instead of a pressure test (paragraph (g)) does not list scuba service. Luxfer's undated FAQ says DOT and the US scuba industry suggest a yearly visual inspection for 6351-alloy cylinders, and that it agrees.

PSI-PCI, an organisation that trains cylinder inspectors, states on an undated page of its own site that visual inspections of scuba cylinders are required annually. We could see that page only in a search summary. So the sources disagree on the legal status: PSI-PCI calls the annual visual required, while the federal rule found sets only the 5-year requalification and the 5-year eddy current check for 6351-T6.

Eddy current: maker versus rule

Luxfer's own requirement, in the same undated FAQ, for its 6351-alloy cylinders is a visual inspection with an eddy current test at least every 2.5 years. That is half the 5-year interval in 49 CFR 180.209(m). Luxfer also stresses that the quality of an inspection matters more than its frequency, and recommends authorised Luxfer service centres or inspectors trained by PSI or ASSET. Those are the maker's statements.

The DAN Alert Diver article of 2017, written by PSI-PCI's president, says US rules allow cylinders that pass the required inspections and tests to stay in service. Cylinder history is covered on cylinders.

Canada: Transport Canada and CSA B339

Transport Canada says periodic requalification of TC cylinders is governed by CSA B339, which the Transportation of Dangerous Goods Regulations adopt by reference, and that the interval depends on the cylinder specification and the gas. A cylinder may only be filled within its requalification period and service life. DOT cylinders are recognised in Canada and are requalified under 49 CFR. Requalifiers in Canada must be registered with Transport Canada under CSA B339 Clause 24, and registration lasts five years.

A catalogue summary, seen only through a search summary, describes CSA B339-2025 as the eighth edition, adding provisions for requalifying seamless cylinders by ultrasonic testing instead of a pressure test. Our research did not find the scuba-specific interval for Canadian-specification aluminium cylinders, so none is given here.

United Kingdom

BSAC, relaying the test body IDEST in March 2020, says recreational diving cylinders in the UK have a full periodic inspection and hydraulic test every five years, and an interim periodic (visual) inspection about two and a half years after the hydraulic test, or sooner where a risk assessment calls for it.

BSAC says BS EN ISO 18119:2018, published in October 2018, replaced BS EN 1968:2002 and BS EN 1802:2002, which stayed current until 31 December 2022, and that the 2.5-year and 5-year intervals for recreational cylinders were kept on a risk-assessed basis. On marking, BSAC (via IDEST) says a hydraulic test is stamped on the cylinder shoulder with the test centre, year and month, a quadrant label shows the next inspection due, and IDEST stopped stamping visual inspections in 2019.

ISO 18119:2018 itself, according to catalogue summaries we could not confirm, covers seamless steel and seamless aluminium-alloy cylinders of 0.5 to 150 litres water capacity and larger tubes, excludes acetylene and composite cylinders, and has amendments from 2021 and 2024.

France: the TIV scheme

France's diving federation, FFESSM, said in a December 2017 professional bulletin that from 1 January 2018, standard diving cylinders still need periodic requalification every 2 years. Cylinders that receive a yearly technical visual inspection under the TIV specification may go 6 years between requalifications, up from 5. Search summaries of FFESSM legal notes describe earlier steps in 2014 and 2015; we did not check the current French legal text, so the present rule is not confirmed here.

When the rules meet

The intervals disagree in both directions. Interim visual inspection is yearly by US industry practice and under France's TIV scheme, about every 2.5 years for UK recreational cylinders, and not set at all by the US federal rule. Full requalification is 5 years in the US and the UK, and 2 or 6 years in France.

Travel adds another layer. DAN Europe notes that a destination country may require its own test stamp or certificate before a cylinder is filled, and that some dive shops will not fill a cylinder whose valve was removed for travel until it has a fresh visual inspection. See travelling with dive gear.

The cylinder test date checker is a companion tool, but only a test station or qualified inspector can say whether a cylinder may be filled.