Nitrogen in the metal treatment process
In 2007, the Atlas Copco Industrial Air Division launched their first generation of nitrogen generators. The PSA nitrogen generators make it possible to bring the right supply of nitrogen to meet every customer’s needs and optimize their production process at the same time.
With advanced nitrogen generators, Atlas Copco provides the ultimate solution: flexible on-site nitrogen generation at the lowest possible cost.
One of the many applications where nitrogen is essential is metal treatment. Nøsted Kjetting a.s. is one of Scandinavia’s leading manufacturers of steel chains. The company’s TRYGG product line is renowned for high quality throughout Europe, North America and Australia. The company replaced its old nitrogen system by an Atlas Copco nitrogen generator.
Already in 1939, Alf Nøsted realised the increase in the number of cars on the Norwegian roads and the resulting increase in car traffic in the winter would create a need for snow chains and he established Norsk Kjettingfabrikk AS (Norwegian Chain Factory) in Mandal.
For more than 65 years the company has marketed the TRYGG (meaning ‘SAFE’ in English) brand name. In 1946 the company changed its name to Nøsted Kjetting AS. Nøsted Kjetting is one of Europe’s leading manufacturers of chains, and together with companies in Lithuania, Sweden, Norway and Montreal, the Nøsted group is today a strong entity with multiple production sites with around 10,000 tons used in production every year.
Even though the transport industry makes up one of its largest customer groups, it's not only vehicles that require chains. Forestry and industry with their tractors and construction machinery are also large-scale consumers. Chains are used on production machinery to protect the rubber. It's also a vital resource for use during lifting in the North Sea (offshore), and for lashing cargo in place on fishing trawlers.
The galvanized chains used in the fishing industry are treated with a particularly high level of zinc to prevent rust. The steel to be galvanized is first sand-blasted. This requirement for improved galvanization is defined by Nøsted Kjetting. These chains are also heat-treated at 950°C, a process that can take up to five hours.
This hardening process takes place under continuous supervision. There is still a degree of manual work involved in chain production. This part of the job mainly takes place at the factory in Lithuania, but the actual heat treatment is carried out in Mandal. There are 90 employees at the Mandal factory, the majority of which are qualified within the professional fields of hydraulics and pneumatics.
The factory has used Atlas Copco compressors for many years and is highly satisfied with both the stability and the quality of the compressed air they supply.
At the same time, they are also extremely pleased with the follow-up both from the local dealer SWT Sørmaskin AS and as Atlas Copco Kompressorteknikk’s (ACK) district manager Odd-Sverre Johansen.
Nøsted uses nitrogen as a part of the atmosphere in the hardening furnace together with propane and methanol. This composition creates a carbon potential in the furnace atmosphere that results in the carbon entering the steel through diffusion. As a consequence, the steel is case-hardened. Nitrogen is also used as a safety gas, to rinse the furnace of explosive gases if necessary.
Their old nitrogen system was connected to a separate compressor. When this compressor needed replacement, Sørmaskin contacted ACK’s Gunnar Nordheim to talk about a new compressor. This was the week after the first generation of nitrogen generators was launched as a part of Atlas Copco’s product range. Gunnar seized the opportunity to discuss nitrogen, which is part of his area of responsibility, and they quickly agreed to present this solution to Nøsted Kjetting. It was soon clear that ACK would be able to meet their demand for nitrogen by attaching a nitrogen generator to the existing compressor system from Atlas Copco. In this way they would no longer need to buy another compressor.
"We use a minimum of 99.5% pure nitrogen, 7.5 m3/h, 24 hours a day, 365 days a year, so we are completely dependent on having a stable production of nitrogen," explains industrial engineer Per Ivar Torland from Nøsted Kjetting, "and that’s what we get now!"
The reactions about the system are very positive. "There are no problems, and our expectations have been exceeded," Torland adds. "We don’t even remember that it’s there.
Cleanliness is superb, we save space and not least we saved the price of a new compressor. At the same time it is highly satisfying for us as a customer that we only need to contact one supplier that we already know to be extremely reliable".
HSE is an important field for Nøsted Kjetting. In addition to taking care of their staff, the company also takes care of the environment. It has a closed production process, i.e. with zero emissions into water or the air. Manufacturing waste is recycled and sold to an engine block foundry.
The company is one of the five largest privately owned industrial firms in Mandal, and in terms of population numbers Mandal is not just a popular holiday destination but also a significant industrial town. Nøsted Kjetting A.S. represents continuity — not just in production but also as a workplace.
It has always stood proudly on its own feet — and will continue to do so…