Greenkote Corrosion Rate in a C5 Environment Revealed

Test site for Greenkote assessment
The test site located on the west coast of Sweden

TCB Ltd is pleased to share the results from an independent test of Greenkote bolts and test panels exposed for a 24-month period in a C5 environment.

Corrosion protection is a critical element of a preloaded bolting assembly. All TCBs from Tension Control Bolts Ltd are supplied with an innovative, eco-friendly Thermo Chemical Surface Modification called Greenkote® which offers advanced corrosion protection as well as significant installation advantages.

TCB Ltd has historically undertaken neutral salt spray testing (ASTM B117) to assess the effectiveness of Greenkote. This has yielded positive results with 3000 hours of salt spray resistance verified. This accelerated corrosion test provides an indication of protection provided by a coating system; however, it’s inherently limited as it’s not an accurate reflection of real-world conditions.

Therefore, TCB Ltd commissioned an independent test by the Research Institute of Sweden (RISE) to test the corrosion rate of Greenkote bolts and test panels subject to atmospheric exposure in a C5 environment over a 24-month period.

The international standard (BS EN ISO 12944-2:2017) classifies a C5 environment as “industrial areas with high humidity and aggressive atmosphere and coastal areas with high salinity.”

The Greenkote test specimens were exposed on the coast of a Swedish island (pictured) and monitored for 2 years. The results were impressive with the comprehensive report concluding that “…the 24 months exposure showed a mass loss / corrosion of the Greenkote coating of approximately 0.2μm/year.”

The nominal thickness of Greenkote is approximately 35μm (microns) which means this represents significant protection against corrosion for Greenkote TCBs even in a highly corrosive C5 environment.