Metal Jacketing Corrosion: The Solution

Pipes, vessels, ducts tanks and other equipment that is subject to extreme hot or cold temperatures must be properly insulated; this helps to conserve energy, prevent condensation and improve safety. In most insulation appli­cations, an outer protective layer known as a metal jacket or is used, which helps to provide resistance to damage.


Different types of metal are used to create this jacketing also referred to as metal cladding. Regardless of which metal is used, the jacketing is susceptible to corrosion on its interior surface, caused by water migrating into the system. Such corrosion can be extremely damaging and even dangerous and so a moisture barrier such as DryMet is always recommended.

DryMet, created and supplied by BS Stainless, is  sometimes referred to in specifi­cations as a  PSMB (Polyfilm Surlyn® Moisture Barrier) and is widely recognised as the most efficient way to prevent interior surface corrosion. It has many salient qualities, including:

  • A proven excellent performance
  • Zero pinholes, so that water cannot ingress
  • Extremely low vapour transmission rate and water absorption
  • Robust, tough and durable manufacture
  • Low flammability
  • Excellent adherence to metal substrates
  • Versatility with different metal types

Only metal jacketing with PSMB should be specified and used, regardless of the type of insulation. The easiest, most effective way to ensure that the jacketing has a PSMB is to use the new ASTM standard, which specifies that it complies with ASTM C1729, Type I, Grade 1 or 2, Class A: DryMet easily meets these standards. This is why other alternatives such as Polykraft which only meets a class C standard is mostly being phased out and replaced by the much superior Surlyn® alternative. The risk of failure in terms of cost and loss time with a inferior metal jacketing system can be catas­trophic.

DryMet can be secured with banding and wing seals also available from BS Stainless. If an acoustic barrier is required, we can also include SoundMet, which will also work as a moisture barrier. In cases where additional external protection from heat is required, we can also supply stainless steel with or without mass-loaded vinyl  but with an external high emissivity PVDF  paint coating CoolMet.

The range of alternatives means that BS Stainless are unique in being able to offer the full spectrum of manufactured metal jacketing to meet all insulation specifi­cations regardless of PVDF,PVF, acoustic or PSMB. 

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