Corrosion is a growing concern across industries, and particularly the wind-power sector, where harsh conditions such as heat, humidity, and air pollution are combined. The Neutral Salt Spray Test (NSST according to ISO 9227) is one of the most established methods to verify corrosion resistance. Nord-Lock Group has officially raised the corrosion resistance on all of its steel wedge-locking washers and promises at least 1,000 hours in salt spray test, ensuring optimum performance over time — even in the most extreme environments.
“Extreme environments demand more,” shares Andrew Radnor, Sales Manager at Nord-Lock Group. “Corrosion will occur sooner or later and can jeopardize the whole application, not just the bolted joint.”
Corrosion occurs when metals come into contact with humid air or water. Corrosion will eventually weaken steel parts and can potentially affect their function, forcing operators to increase repairs, which decreases productivity. It can affect structural integrity and therefore cause accidents.
Understanding exactly how extreme factors such as pollution are affecting applications and use this experience as the basis for product developments is increasingly important. Whatever the environment, Nord-Lock Group collaborates with customers globally to meet needs and specifications including providing necessary certifications.
“Customers need washers that can withstand extreme environments for a longer period of time,” explains Anders Knutsson, Coating and Corrosion expert at Nord-Lock Group. “Based on this, we continuously put more focus on increasing the corrosion resistance of our standard products.”
Although 1,000 hours is the official number released by the Group, this is just the minimum amount of time Nord-Lock steel washers with zinc flake coating by Delta Protekt can withstand corrosion in a salt spray test. The quality testing that the group does as part of ensuring their high-quality standards clearly shows that the washers generally endure much longer.
“We have perfected our coating process so that we can guarantee 1,000 hours,” says Knutsson. “But if you look at the results of the salt spray tests that we do every week, the washers on average do endure over twice as long in the salt spray chamber before any signs of corrosion occur.”
According to ISO 12944-6:2018, 1,000 hours in a salt spray chamber corresponds to at least C4 High or C5 Medium conditions. The Nord-Lock standard range includes Nord-Lock Original Washers and X-Series washers with standard and enlarged (SP) outer diameter and Steel Construction (SC) Washers. High corrosion resistance for such a large range of washers lets customers secure applications when facing a wide variety of challenges. This is particularly helpful when the industry uses galvanized bolts, which, combined with Nord-Lock steel washers, provide high corrosion resistance for the whole assembly.
Galvanized bolts are used within the wind-power industry and, according to Sales Manager Brian Troest, pairing them with Nord-Lock steel washers is beneficial as more and more wind turbines move offshore. “Steel washers are used onshore and offshore, inside the towers and on blade bolts, where they can be exposed to the environment,” says Troest.
“Galvanized bolts are often used in construction,” adds Radnor. “If steel washers are used in a polluted environment with galvanized bolts, the combination is very durable against corrosion. The high quality of the coating on the Nord-Lock washers allows us as a company to offer one washer to fit all the scenarios for steel.”