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Understanding CSA 6.18-02 (2017): Technical Requirements for Gas Appliance Connectors
Comprehensive guide to the 2017 reaffirmation of Canada’s standard for corrugated stainless steel tubing connectors and flexible gas appliance connectors
Scope and Applicability
CSA 6.18-02 (2017) is the reaffirmed edition of the Canadian Standards Association standard for connectors for gas appliances. This standard specifies material, construction, performance, and marking requirements for corrugated stainless steel tubing (CSST) connectors used to connect residential, commercial, and industrial gas appliances to fuel supply lines. Originally published in 2002 and reaffirmed in 2017, CSA 6.18 continues to be a key reference for manufacturers, installers, and inspection authorities across Canada.
The standard covers connectors intended for natural gas, manufactured gas, liquefied petroleum (LP) gas, and LP gas-air mixtures. It is applicable to connectors with nominal diameters up to 2 inches (50 mm) for both indoor and outdoor installations. Notably, this standard does not apply to interior gas piping systems or gas hoses for portable appliances, which are covered under separate standards such as CSA Z21.24 or ANSI Z21.69.
Tip: CSA 6.18-02 (2017) is harmonized with the requirements of CSA B149.1 (Natural Gas and Propane Installation Code) and is referenced by most provincial gas authorities. When specifying connectors for a residential range or commercial kitchen appliance, check that the product carries a valid CSA 6.18 certification mark.
Technical Requirements and Performance Criteria
Material Specifications
CSA 6.18-02 (2017) requires connectors to be constructed from Type 304 or 316 stainless steel with minimum 0.010 in (0.254 mm) wall thickness. The corrugated tubing must be annealed after forming to restore corrosion resistance and ductility. End fittings must be brass, stainless steel, or other approved corrosion-resistant alloy. O-rings and seals must be of a material compatible with the intended gas type and operating temperature range (-40 °C to 80 °C).
Construction and Dimensions
The standard defines specific dimensional tolerances for connector length, corrugation geometry, and fitting connections. Table 1 summarises the major dimensional and performance criteria.
| Parameter | Requirement | Test Condition |
|---|---|---|
| Nominal diameter (NPS) | 1/2 in, 3/4 in, 1 in | Measured per ASME B1.20.1 |
| Minimum wall thickness | 0.010 in (0.254 mm) | Micrometer measurement (per ASTM A240) |
| Annealing temperature | ≥ 1010 °C (1850 °F) | Bright anneal in controlled atmosphere |
| Maximum length | 6 ft (1.8 m) for indoor; larger with reinforcement | Straight pull test per Clause 7.3 |
| End fitting retention | No separation under 200 lb (890 N) axial load | 5 min hold at 200 lbf |
Pressure and Leak Testing
Every connector must pass both a factory hydrostatic test at 2.5 × maximum allowable working pressure (MAWP) and a pneumatic leak test at 1.1 × MAWP. For typical 0.5 psi gas connectors, this equates to 1.25 psi and 0.55 psi respectively. Table 2 summarises the leak tightness criteria.
| Test Type | Test Pressure | Duration | Acceptable Leak Rate |
|---|---|---|---|
| Hydrostatic (factory) | 2.5 × MAWP (min 3.8 psi) | 60 s | No visible leakage |
| Pneumatic (production or field) | 1.1 × MAWP (1 min hold) | 60 s | ≤ 0.001 m³/h per metre of connector length |
Warning: Reuse of previously installed CSA 6.18 connectors is discouraged. The corrugated tubing can stress‑corrosion crack if subjected to repeated bending or exposure to harsh chemicals (e.g. cleaning agents containing chlorides). Always install new connectors when replacing an appliance.
Corrosion Protection
All external steel parts must be protected with a zinc electroplating (≥ 5 µm) or polymer coating that passes a 500-hour neutral salt spray test per ASTM B117. For connectors installed in coastal or industrial environments, Type 316 stainless steel is strongly recommended.
Marking, Installation, and Implementation Highlights
CSA 6.18-02 (2017) mandates permanent legible marking on each connector stating:
- Manufacturer’s name or trademark
- CSA standard designation (CSA 6.18-02)
- Gas type(s) for which it is rated (NG, LP, or both)
- Date of manufacture (year and week)
- Maximum allowable working pressure
- Length (in inches or centimetres)
During installation, the connector must not be stretched more than 5% of its original length nor subjected to continuous torsion. The installer must verify that the connector is not in contact with any sharp edge or heat source exceeding 110 °C. The standard also requires that connectors be equipped with a bonding device or listed bonding clamp if used in a CSST system requiring electrical continuity.
Success: By specifying CSA 6.18-02 (2017) certified connectors, contractors ensure compliance with the National Building Code of Canada (2015, 2020) and most provincial gas codes. These connectors have a proven safety record and are often the only type allowed by local authorities for residential range and clothes dryer connections.
Compliance Notes and Certification
Manufacturers seeking CSA 6.18 certification must submit representative samples to an accredited laboratory (e.g., CSA Group, CSA International) for testing per the standard. A factory inspection and annual re‑audit are required to maintain certification. Connectors that meet the standard bear the CSA registration mark (blue star or gas‑specific mark) on the product or its packaging.
It is important to note that CSA 6.18-02 (2017) is a reaffirmation of the 2002 edition; no substantive technical changes were introduced in 2017. Nonetheless, any product marked with the new date (2017) should be considered equivalent to the original edition. For exports, note that the U.S. parallel standard is ANSI Z21.24 (connectors for natural gas appliances) and ANSI Z21.75 (connectors for outdoor gas appliances). While harmonisation efforts have aligned many requirements, differences remain in pressure ratings and end‑fitting dimensions.
Danger: Use of non‑certified connectors voids the appliance warranty and can lead to catastrophic gas leaks. If a connector does not display the CSA 6.18 mark or has evidence of corrosion, kinking, or damaged threads, it must be replaced immediately. In many jurisdictions, the lack of a CSA mark is grounds for a gas safety shut‑off by the utility or inspector.
Frequently Asked Questions
Q: What is the difference between CSA 6.18-02 (2017) and CSA 6.18-02 (2002)?
A: As a reaffirmation, the 2017 edition contains no technical changes. It simply reaffirms that the 2002 version is still the current acceptable standard. Products may be marked with either year, but the newer date indicates the manufacturer has attested ongoing compliance.
A: As a reaffirmation, the 2017 edition contains no technical changes. It simply reaffirms that the 2002 version is still the current acceptable standard. Products may be marked with either year, but the newer date indicates the manufacturer has attested ongoing compliance.
Q: Can I use an older CSA 6.18 connector that was previously installed on another appliance?
A: CSA 6.18-02 (2017) explicitly discourages reuse. The corrugated tube may have work‑hardened or been exposed to contaminants. Always use a new, certified connector for each installation to ensure leak‑tight performance.
A: CSA 6.18-02 (2017) explicitly discourages reuse. The corrugated tube may have work‑hardened or been exposed to contaminants. Always use a new, certified connector for each installation to ensure leak‑tight performance.
Q: Is CSA 6.18 the same as ANSI Z21.24?
A: They are similar but not identical. CSA 6.18 includes additional requirements for sizing, marking, and longer length validation. Connectors certified to CSA 6.18 are generally accepted in Canada, while ANSI Z21.24 is for the U.S. Some dual‑certified products exist.
A: They are similar but not identical. CSA 6.18 includes additional requirements for sizing, marking, and longer length validation. Connectors certified to CSA 6.18 are generally accepted in Canada, while ANSI Z21.24 is for the U.S. Some dual‑certified products exist.
Q: Are flexible gas connectors (e.g., braided stainless steel hoses) covered by this standard?
A: No, CSA 6.18-02 (2017) specifically covers corrugated stainless steel tubing connectors. For braided or non‑corrugated flexible connectors, refer to CSA Z21.69 (for appliance connectors) or CSA 6.26 (for gas range connectors).
A: No, CSA 6.18-02 (2017) specifically covers corrugated stainless steel tubing connectors. For braided or non‑corrugated flexible connectors, refer to CSA Z21.69 (for appliance connectors) or CSA 6.26 (for gas range connectors).
© 2026 – This technical article is prepared for informational purposes and is not a substitute for the official CSA 6.18-02 (2017) standard.