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CSA G189-1966 (1998): Specifications for Sprayed Metal Coatings for Atmospheric Corrosion Protection
A Comprehensive Guide to the Canadian Standard for Thermal Sprayed Zinc and Aluminum Coatings
CSA G189-1966 (1998) is a Canadian standard developed by the Canadian Standards Association (CSA) that specifies requirements for sprayed metal coatings applied to steel surfaces for protection against atmospheric corrosion. First published in 1966 and reaffirmed in 1998, this standard remains a key reference for thermal spray coating applications in Canada, particularly for infrastructure, bridges, and industrial structures.
Scope and Applicability
This standard covers the application of sprayed metal coatings of zinc, aluminum, or their alloys to carbon steel and low-alloy steel structures for atmospheric corrosion protection. It is intended for coatings applied by thermal spraying processes, including flame spraying and electric arc spraying. The standard is applicable to new structures as well as maintenance and repair of existing coatings.
The standard excludes coatings intended for immersion service in water or chemicals, high-temperature applications above 200°C, or environments where the coating may be subject to mechanical abrasion beyond normal atmospheric exposure.
Tip: While CSA G189-1966 (1998) applies to atmospheric exposure, designers should consult additional standards (e.g., CSA S832, ISO 2063) for coated structures in more severe environments.
Technical Requirements
Surface Preparation
The standard mandates that all steel surfaces be cleaned and prepared to achieve a near-white metal finish, equivalent to SSPC-SP 10 or NACE No. 2 (ISO 8501-1 Sa 2½). Abrasive blasting is the preferred method, using clean, dry grit to remove all rust, mill scale, and contaminants. A surface profile of at least 50 µm (2 mils) is required for adequate mechanical adhesion of the sprayed metal coating.
Coating Materials
The standard specifies that coatings shall be applied using metal wires or powders of certified composition. Zinc coatings shall contain at least 99.5% zinc (ASTM B833 or equivalent). Aluminum coatings shall be 99.0% aluminum minimum. Zinc-aluminum alloys (85/15 or similar) are also permitted, provided they meet the performance requirements. The use of recycled or reclaimed material is restricted unless proven to meet the standard.
Application Methods
Thermal spraying shall be performed using equipment capable of consistent melting and propulsion of the coating material. The standard permits both flame spraying and electric arc spraying. Operators must be qualified and demonstrate the ability to produce coatings meeting thickness and adhesion criteria. Application should be carried out in clean, dry conditions with substrate temperature above 5°C and relative humidity below 80% to prevent condensation.
Warning: Inadequate surface preparation or poor spraying technique can lead to coating delamination. The standard requires all spraying to be carried out within 4 hours of surface preparation to prevent re-oxidation or contamination.
Coating Thickness
The minimum coating thickness is determined based on the corrosivity of the environment and the required service life. Table 1 summarizes the thickness requirements from the standard.
| Service Condition | Zinc Coating (µm) | Aluminum Coating (µm) |
|---|---|---|
| Rural / Mild | 80 | 120 |
| Urban / Industrial | 120 | 160 |
| Marine / Coastal | 150 | 200 |
| Severe / Chemical | 200 | 250 |
The standard also permits thicker coatings provided they are applied in multiple passes to avoid stress buildup. Coatings must be applied as uniformly as possible, with localized variations not exceeding ±20% of the specified thickness.
Testing and Inspection
Adhesion (Bond Strength) Test
The standard requires adhesion testing using a peel or pull-off test method. For routine inspection, a simple knife test (cutting through the coating) can be used to ensure there is no lifting or disbonding. For performance-critical applications, a quantitative pull-off adhesion test per ASTM D4541 or ISO 4624 is recommended, with minimum bond strength of 3 MPa for zinc and 4 MPa for aluminum coatings.
Success: Coatings that achieve these bond strengths have demonstrated excellent long-term performance in Canadian infrastructure projects, including bridges in coastal British Columbia and industrial structures in Ontario.
Thickness Measurement
Coating thickness shall be measured using non-destructive magnetic induction or eddy current gauges as per ASTM E376. The standard requires at least five measurements per 10 m² of coated area, with the average of all readings meeting the specified minimum. If local areas fall below the minimum, additional coating passes are required.
Compliance and Quality Assurance
To certify compliance with CSA G189-1966 (1998), applicators must implement a quality control plan covering:
- Pre-qualification of materials and equipment
- Operator training and certification
- Surface preparation inspection (profile, cleanliness, dust)
- In-process monitoring of spray parameters (temperature, distance, angle)
- Final inspection: thickness, adhesion, visual quality
- Documentation and record-keeping
The standard is referenced by building codes and specifications for public works in Canada. Third-party inspection by an accredited agency is often required for projects under federal jurisdiction.
Important: Non-compliance with CSA G189-1966 (1998) can result in premature coating failure and voided warranties. It is essential that all parties involved in the specification, application, and inspection of sprayed metal coatings adhere strictly to the requirements of this standard. As of 2026, this standard remains a mandatory reference for many Canadian structural steel contracts.
Frequently Asked Questions
Q: What is the difference between CSA G189-1966 and ISO 2063?
A: CSA G189-1966 (1998) is a Canadian standard specifically for atmospheric corrosion protection of steel, while ISO 2063 is an international standard covering thermal spraying for both corrosion protection and other applications. CSA G189 is more prescriptive in thickness requirements for specific Canadian environments. Both standards share similar principles, but local regulations often mandate CSA compliance in Canada.
A: CSA G189-1966 (1998) is a Canadian standard specifically for atmospheric corrosion protection of steel, while ISO 2063 is an international standard covering thermal spraying for both corrosion protection and other applications. CSA G189 is more prescriptive in thickness requirements for specific Canadian environments. Both standards share similar principles, but local regulations often mandate CSA compliance in Canada.
Q: Can CSA G189-1966 coatings be used for offshore or underwater structures?
A: No. The standard explicitly excludes coatings intended for immersion service. For such applications, refer to CSA S832 or ISO 2063-3 with additional sealing treatments.
A: No. The standard explicitly excludes coatings intended for immersion service. For such applications, refer to CSA S832 or ISO 2063-3 with additional sealing treatments.
Q: Is the standard still current?
A: The standard was reaffirmed in 1998 and remains a valid CSA standard. However, users are encouraged to check for the latest edition or any amendments. As of 2026, CSA has not withdrawn it, but newer standards like CSA G189-22 (if exists) may offer updated requirements. Always verify the current revision status before specification.
A: The standard was reaffirmed in 1998 and remains a valid CSA standard. However, users are encouraged to check for the latest edition or any amendments. As of 2026, CSA has not withdrawn it, but newer standards like CSA G189-22 (if exists) may offer updated requirements. Always verify the current revision status before specification.
Q: What qualifications are required for operators?
A: The standard requires that operators be trained and certified in thermal spray coating. Although it does not specify a particular certification body, many projects require NACE or SSPC certification. The applicator must demonstrate consistent quality through documented test panels and in-process controls.
A: The standard requires that operators be trained and certified in thermal spray coating. Although it does not specify a particular certification body, many projects require NACE or SSPC certification. The applicator must demonstrate consistent quality through documented test panels and in-process controls.