Three Words & One Meaning — What Are They?
Corrosion. Oxidisation. Rust. These are three words guaranteed to strike fear into the heart of anyone who relies upon metal jacketing as an efficient and effective insulation system. As insulation is a necessary component of countless machines and systems, metal jacketing is all around us all the time and it’s important that you familiarise yourself with how it works, how it is installed and what can go wrong. Get the facts on metal jacketing corrosion from BS Stainless here.
Insulation keeps systems at an accurately-steady temperature, ensuring that optimum operation of that system is constantly achieved - this keeps safety as number one priority, productivity levels high, downtime low, costs effective and predictable, system lifespans long and managers happy! Most materials used for their insulating properties have a converse susceptibility to moisture, which can render them completely ineffective and unfit for purpose, leading to a loss of the many positive aspects previously mentioned.
Metal jacketing aims to prevent this moisture, often rain or seawater, from ever reaching the sensitive insulation material - preventing moisture ingress ensures the insulation works as it should and that ideal conditions for corrosion are not created. As well as this crucial primary function, metal jacketing systems also protect the underlying insulation from mechanical abuse or damage.
Materials currently used for metal jacketing include stainless steel, aluminium, Aluzinc and aluminised steel - the selection is based on a number of factors including application, placement and environment, all of which must be carefully considered. Sheets of the chosen metal are wrapped around the insulation and made secure with metal banding, closing up longitudinal and circumferential overlaps with sealant (usually silicon-based) as work progresses.
Mechanical abuse, turbulent fluid flows causing vibrations and natural contract/expand thermal cycles all subject the sealant to high stress, often causing failure as the effects build up over time. Any break, however minute, in the seals opens up a clear route for moisture ingress to promote corrosion under the jacket and cause it to ultimately fail.
BS Stainless have developed innovative solutions to the two main types of corrosion, which are:
Galvanic Corrosion - caused when two different metals touch in the presence of electrolytes. Often occurs between jacket and pipe, though can happen around ancillaries such as wing seals and banding. DryMet, our metal jacketing featuring special DuPont™ Surlyn® film, prevents any metal-to-metal contact now also available as Drymet Band and Drymet Band Ecoseals ideal for using stainless steel banding over Galvanised, Aluminised or Aluzinc steel to prevent corrosion.
Pitting Corrosion - a localised effect caused by passivation film being removed, damaging the exposed material beneath (the ‘pit’) and making it more susceptible to corrosion which is exacerbated further by moisture. Considered particularly dangerous due to its localised nature which can easily be missed during standard inspections, pitting corrosion can be prevented with our CoolMet, TedMet and DryMet metal jacketing innovations.