| Why does the chain need to do the salt spray test?
Carbon steel chains have good strength and wearing resistance. However, in corrosive environment, the chains are easily got rusted. Most of the corrosion is caused by the exposure to atmospheric environment, and the most common and destructive is salt spray corrosion.
With the advancements in metal anti-corrosion technology, MCC has introduced various anti-corrosive coatings, including nickel plated, zinc plated, GN, CRF coatings and so on.
To assess the protection ability of coating against the corrosion, a testing method that is fair and close to corrosive condition of natural environment is necessary.
Since salt spray corrosion is the most common factor lead to rusted metal, scientists have developed Salt Spray Test (SST) to simulate the severely corrosive condition and examine the rusted process. Currently, the salt spray is one of the most widespread corrosion testing methods.
Extended Reading
| Salt Spray Testing Standard
| ASTM B117 | ISO 9227 | |
| Density, g/cm3 | 1.024286-1.037261@25°C | 1.029-1.036@25°C |
| Mass of NaCl required per 1 L | 53 ± 10.6 g | 50 ± 5 g |
| Electrical conductivity | Max 5.0 µS/cm at 25°C | Max 20 µS/cm at 25 °C ± 2 °C |
| Allowable Limits for Impurity Levels in Sodium Chloride |
Total impurities ≦0.3% Halides (bromide, Fluoride and iodide) ≦0.1% Copper < 0.3 ppm Anti-caking agents none added |
Total impurities≦0.5% Copper +Nickel +Lead≦0.005%(50ppm) Sodium iodide≦0.1% Anti-caking agents none added |
| Specimens suspended angle | 15-30° | 15-25° |
| Salt concentration | 5% | |
| pH range | 6.5 to 7.2 | |
| Temperature | 35 +/- 2°C | |
| Atomization and Quantity of Fog | For each 80 cm2 of horizontal collecting area, there will be collected from 1.0 to 2.0 mL of solution per hour. | |
| Salt Spray Testing Method
1. Pictures of salt spray machine
2. Working principle of salt spray test machine
| Salt Spray Test Result
| Application
- Ensure the quality of anti-corrosive coating : Make sure chains’ anti-rust performance reach the standard.
- Improve the anti-rusted performance: When improving the anti-corrosion coating, salt spray is used to find the best process.
- Develop new coating : With the continuous development of corrosion resistant technology, salt spray test is the best method to examine the performance of new coating..
- Examine the chain lubricant protection against corrosion
| FAQ
SST is an accelerated corrosion test that atomizes a NaCl solution in a heated chamber to simulate severe atmospheric conditions. It helps evaluate how coatings (e.g., nickel plated, zinc plated, GN, CRF) protect chains in corrosive environments.
ASTM B117 and ISO 9227 are widely used. This article references ASTM B117, which specifies chamber temperature, salt concentration (5%), pH, fog collection rate, specimen angle, and other parameters.
Not necessarily. SST is a comparative lab method. Real service life also depends on temperature, humidity cycles, pollutants, cleaning chemicals, load, and lubrication. Use SST hours to compare coatings under the same standard, not as a direct lifespan guarantee.
Choose CRF when you need stronger protection in frequent washdown, coastal air, or areas with aggressive salts/acids. For mild environments, nickel or zinc plating may be sufficient and more cost-effective.
Thin protective coatings are designed to maintain mechanical properties within specification. Always check the datasheet for allowable working load and wear limits after coating.
Keep chains clean, relubricate on schedule, avoid chloride-rich cleaners unless compatible, and protect idle equipment from condensation or salt fog. Selecting the right coating for your environment is the first step.
