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  Don’t let corrosion make you stressful

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​​​Don’t let corrosion make you stressful ​

​​Stress corrosion cracking (SCC) is one of the most devastating forms of corrosion, developing from microscopic flaws in the structure of austenitic stainless steel that are invisible to the naked eye until it’s much too late. Kaiflex has always been engineered to help minimise the risks of stress corrosion but by providing a cell structure completely free from halogens, Kaiflex HFplus takes things even further.

When most people think of corrosion their minds are naturally drawn to galvanic corrosion – colloquially referred to as ‘rust’. Corrosion is, more generally, however the gradual degradation of a metal by chemical processes. Stress corrosion occurs in austenitic stainless steel when a combination of high temperatures and chlorine ions concentrated along microscopic stress lines in the steel causes very localised corrosion.​

Leachable chlorine

​​Chlorine is the 19th most common element on Earth and is found just about everywhere. Fluoride, the halogen that is a near cousin to chlorine and has similar effects, is even added to tap water in large parts of the country.

​​When chlorine is allowed to dissolve into water it can be washed and deposited into the shallow cracks in a stainless steel surface. Only when concentrated in this way can chlorine drive the chemical processes that cause SCC in stainless steel.

​​If the pipework is completely dry, then there is no medium to allow the leachable halogens to become concentrated. Keeping pipework dry and free from moisture is, therefore, a large part of preventing SCC.

All Kaiflex is closed cell and intended to prevent water vapour from penetrating to the pipe surface, dramatically reducing the risks of SCC.

Halogen free for an even lower stress corrosion risk

​​Halogen based compounds are ideal flame retardants and a wide variety of products to provide superior fire performance. Quantities vary however and standard Kaiflex grades, such as Kaiflex ST, feature a very low halogen content of less than 0.02%.

​​Kaiflex HFplus offers an even lower halogen content. Infact, Kaiflex HFplus is completely halogen free. That means there are no leachable halogens at all in the material and this, combined with the same moisture resistant closed cell structure you’d expect from Kaiflex, means that Kaiflex HFplus offers one of the best ways to reduce the risks of stress corrosion.

Halogen free for a low fire and smoke risk

​​What’s more, despite being free from halogenated flame retardants, Kaiflex HFplus exhibits strong fire performance and is Lloyds Register approved for offshore use (based on the results of tests in accordance with the IMO FTP-Code Part 5 fire test).

New for 2016 Kaimann has also sought the fire classification for Kaiflex HFplus under the EN 13501-1 standard. The product is now officially classified Dls2 for tubes and Ds3 for sheets.​

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Stress corrosion cracking (SCC) is one of the most devastating forms of corrosion, developing from microscopic flaws in the structure of austenitic stainless steel that are invisible to the naked eye until it’s much too late.

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Article Date
2/25/2016
Target
blog-technical-insulation