When the demands for lifespan are high
Steel designed for use in highly corrosive environments requires extra protection on account of the high demands made on its service life. This may be relevant for special offshore structures, bridge elements, aquaculture equipment, jetties and roads. Some structures and buildings are constructed in locations where future maintenance is difficult to perform. In such cases, it is essential to apply optimal corrosion protection of the type the NOT-processes® provide.
The NOT-processes® constitute a Duplex system that consists of one or more surface treatments applied to hot-dip galvanised steel. This elevates carbon steel to the highest corrosion class and opens the door to a wide range of colour combinations and high finishes. Norsk Overflate Teknikk AS provides two different processes.
The NOT-processes® as a Duplex system has a much longer lifespan than the coatings individually.
Formula for assumed lifespan:
Explanation of formula:
LT: Assumed lifespan of the duplex system
K: Environment-dependent synergy factor
1.5 for environmental class C5 or when permanently submerged in water. 1.6-2.2 for environmental class C3-C4 or when the wet time for the system is less than about 60%. 2.1-2.3 for environmental class C2.
LZn: Lifespan of the zinc coating
In years and the current environment.
LM: Lifespan of the paint coating
In years and the current environment if applied directly to steel.
The NOT-processes® are executed in accordance with the following standards
- Hot-dip galvanisation in accordance with NS-EN ISO 1461
- Powder coating in accordance with NS-EN 13438
- Coating and painting in accordance with Norwegian Standard M-501
- Surface treatment in accordance with corrosion classes, cf. the NS-EN ISO 12944-2 standard
Why hot-dip galvanise?
In and of itself, hot-dip galvanising steel provides excellent protection. The process results in the best possible rust-protection of steel and assures a long service life free from maintenance. It is also the most economical option for surface treating steel. In hot-dip galvanisation, zinc and iron react with one another to form an alloy. The service life is typically 50–100 years, depending on climate conditions.