Two case histories, one method
Cortec published two pieces in recent weeks that describe the same preservation method applied to very different assets. One is an article on protecting turbines during transport, layup and outdoor storage, with field results from three countries. The other is Case History #434, in which a tracked reconnaissance vehicle was prepared for up to three years of outdoor storage at low cost. The products and the sequence are nearly identical, and they are the same ones we quote for a fabricated machine base, a compressor skid or a blasted and painted weldment that has to sit in a yard until the customer’s site is ready.
What the turbine article says
Turbine components move through tropical and marine environments, sit through temperature and humidity swings in warehouses, and often wait months between delivery and commissioning. The corrosion that starts in that window shows up later as maintenance cost and delay. Cortec’s method, in the article’s terms, is a layered one: VpCI heat-shrink film on the outside that protects physically, contains the vapor and releases inhibitor continuously; VpCI emitters inside to raise the concentration in enclosed volumes; and misting fluids for large internal volumes such as casings and piping.
The field results Cortec cites: turbines at a power plant in the United Kingdom stored outdoors for several years; a gas turbine that traveled more than 9,000 kilometers to Kazakhstan without degradation; and five turbine-generator units in Indonesia preserved for two years before commissioning. In every case the equipment went into service without a pre-service cleaning or degreasing step, because the VpCI layer dissipates on its own.
What Case History #434 says
The vehicle was a CVR(T) Scimitar, a tracked armored reconnaissance vehicle. The requirement was outdoor storage for up to three years at a cost well below indoor climate-controlled storage. The preservation used three Cortec products:
- VpCI-132 foam placed at multiple points around the exterior of the vehicle to supply inhibitor inside the wrap.
- VpCI-101 emitter devices installed inside the electronics boxes to protect contacts and boards.
- VpCI-126 HP UV shrink film applied over the whole vehicle with heat-shrink equipment as the outer envelope, UV-stabilized for outdoor exposure.
The coolant, oil and fuel systems were also treated with corrosion-inhibiting additives so the vehicle could be stored wet. The result was a vehicle that could sit outside for three years and return to service without a rebuild.
The method, written for a fabricator or machine builder
Strip the aerospace and defense context out and this is the routine. It applies to a blasted and primed structural weldment waiting for a construction schedule, a machine tool sold but not yet delivered, a gearbox or pump skid staged for a plant outage, or a customer’s own equipment parked during a line shutdown.
1. Start clean
Wash or degrease machined surfaces. For weldments and structures, the blast booth or blast room is the cleaning step, and freshly blasted steel is the most corrosion-prone surface in the plant. It needs to be primed or wrapped the same day. For parts and sub-assemblies, a Build-All or Magido aqueous washer gets them clean and dry before they go into the wrap.
2. Put inhibitor inside the envelope
The outer film alone will not saturate the air around a large asset. Place VpCI-132 foam pads or BioPad emitters at intervals across the equipment, more in enclosed or shaded pockets. Put a VpCI emitter inside every control panel, junction box and motor terminal box, sized to the box volume. Cortec’s emitter range covers 1, 5 and 11 cubic feet per device, and they are replaced every six months to a year depending on the environment. Add Desicorr VpCI pouches where the wrap will see high humidity.
3. Fog or flush internal volumes
Casings, tanks, hydraulic reservoirs and piping get a VpCI misting fluid or a fill-and-drain with a VpCI additive, the equivalent of the coolant, oil and fuel treatment in the Scimitar case. Our VpCI product selection guide lists the liquids by system.
4. Wrap and shrink
For outdoor storage, use a UV-stabilized VpCI shrink film. MilCorr is the 10 mil heavy-duty film for multi-year outdoor exposure, and VpCI-126 HP UV is the 10 mil UV-stabilized version of the standard blue film, which is what the Scimitar case used. Shrink the film with a heat gun or torch, tape the seams with shrink tape, and add a vent or desiccant port if the asset will see large temperature swings. The step-by-step is in how to shrink wrap equipment with MilCorr. The film is not a walking or load-bearing surface.
5. Leave it closed
Every time the wrap is opened the inhibitor concentration drops and the emitters have to rebuild it. If inspections are required, add an inspection window or zipper door at the wrap stage rather than cutting the film.
Which products
- MilCorr VpCI shrink film, 20 x 210 ft, 10 mil and 20 x 100 ft for multi-year outdoor storage
- VpCI-126 Blue HP UV shrink film, 20 x 100 ft, 10 mil, the film used in Case History #434
- VpCI-126 Blue HP shrink film, 6 mil for indoor or covered storage
- Shrink tape for seams and patches
- BioPad emitters and VpCI-132 foam pads for inside the wrap
- VpCI-101, VpCI-105 and VpCI-111 emitter devices for control panels, junction boxes and electronics enclosures (1, 5 and 11 cubic feet)
- Desicorr VpCI pouches, 1 unit, and 4 and 8 unit pouches by quote
Talk to us
Tell us what the asset is, its rough dimensions, whether it will sit inside or out and for how long, and we will spec the film, the emitter count and the liquids for the internal systems, and quote it as a kit. Contact us.
Sources: Cortec Corporation published article and Cortec Case History #434.
