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Corrosion Control Packaging

CORR-EX VCI Anti-corrosion storage bags

  • Corrosion protective packaging for storage of cleaned machined parts, using volatile corrosion inhibitors to prevent in-storage corrosion.
  • Anti-corrosion packaging is compatible with all metals and many plastics and other composite materials.
  • CORR-EX VCI packs are very simple to use, produced in a range of sizes, from polythene or PPE film impregnated with the volatile corrosion control liquid. Safe on the parts and safe for operators to handle and has no impact on the environment.
  • The corrosion inhibitors constantly vaporise inside the bags to form a protective film on the parts while in-store disappearing instantly when the parts are exposed to the atmosphere leaving no traces on the surface. Parts removed from the bags must be processed within an hour but can be replaced in the bags if there is a delay in further processing or another period of intermediate storage is needed.
  • CORR-EX VC bags are effective for at least 12 months if not opened.

Corrosion Control Packaging Using Corrosion Inhibitors

EnviroTech Surface Technologies (ETE) specialise in super critical cleaning for metal parts. The EnSolv range of cleaning solvents are so effective in removal of oil that all the metal surfaces are liable to corrode very quickly as they now have no protection from the corrosive effects of atmospheric moisture. Recognising this problem ETE have developed impregnated plastic storage bags and film wrapping which prevent in storage corrosion for long periods. During production of metal parts many mechanical procedures are used, machining, bending, lapping, honing, drilling, grinding, punching all of which use oils to speed these operations. Whether for the automotive manufacturers or their tiered suppliers, medical equipment manufacture or aerospace production, cleaning is essential to remove oil and coarse contamination between machining, inspection and final delivery of completed item.

Cleaning products and processes are increasingly sophisticated, formulated to remove all traces of cutting oils and grinding fluids from machined parts and from welded mild steel sheet fabrications. These process oils give corrosion protection under normal circumstances but once removed atmospheric corrosion can occur very quickly as mechanical production processes remove the oxide layers which form a natural protective coating exposing active metal surface to rusting and corrosion.

The most efficient form of cleaning for metal parts is vapour degreasing which relies on the difference between the surface of the parts to be cleaned being at ambient temperature and the the vapour formed by boiling, usually halogenated hydrocarbon solvents, such as EnSolv, a stabilised n-propyl bromide being much higher (temperature gradient typically 20 to 73C). More accurately referred to as Condensation cleaning it is the change of state from vapour to liquid on the cooler metal surface which dissolves the oils and removes other surface contaminants.

Due to the temperature changes on removal of the warmed parts from the degreasing tank to ambient temperatures a microclimate is formed in the basket containing the parts or on the fabricated metal structures. The humidity changes within the micro climate allow moisture to condense on surfaces as parts cool. The condensed moisture contains minute amounts of acidic products such as sulphur dioxide, nitric acid and hydrogen chloride from the atmosphere. Totally clean, unprotected, surfaces devoid of oil are vulnerable to electrochemical processes with corrosion cells forming very quickly on the metal the moisture acting as an electrolyte causing rust or other corrosion products from the electrolytic processes on the metal surfaces.

If the processed parts are quickly painted, powder coated or surface treated in some other way against corrosion this is not a problem. But most machined and engineered parts are an intermediate process where many parts may be marshalled together for assembly of the final article. These are stored until needed in bins or on shelves where the corrosion process will continue making quality control difficult and reject rates very high.

To overcome storage corrosion it is traditionally the case that parts are stored with oil on the surface then cleaned immediately prior to assembly or finishing. This is a simple but messy solution for small scale production but as production rates increase and “just in time” assembly methods are employed, with parts supplied from other specialist tiered suppliers cleaning at the assembly stage becomes impractical.

Further information

We can provide you with a Material Safety Data Sheet, independent laboratory reports, product samples or technical assistance. For more information or advice please contact us by telephone on +44 (0) 20 8281 6370 or use our contact form.

CORR-EX corrosion protection products are supplied and supported by EnviroTech Europe Ltd.  Manufactured in the United Kingdom and available on short delivery times through our dedicated team of distributors in Europe and the Middle East.

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