Description
VpCI®-329 is an oil-based vapor corrosion inhibiting concentrate that turns the lubricating, hydraulic or preservation oil already in a machine into a rust preventative. Dilution sets the term: 1:20 for short-term protection, 1:10 for medium-term and 1:5 for long-term. It has high flash and fire points and conforms to three military specifications, which is why it is the standard additive for gearbox, crankcase and hydraulic-system lay-up. The 5-gallon pail treats roughly 20 to 95 gallons of oil depending on the ratio, enough for a bank of gearboxes or one large hydraulic reservoir.
When equipment sits idle the oil drains off gear teeth, bearing races and cylinder walls above the sump level, and condensation does the rest. VpCI-329 answers that two ways: the oil-soluble inhibitors leave a tenacious contact film on everything the oil wets, and the vapor phase inhibitors migrate through the head space and condense on the uncoated metal, so the whole interior is protected in both the liquid and vapor phases. Because it contains no chromates, nitrites or phosphates it can stay in the oil when the machine returns to service. In the Cortec Product Consultation Guide VpCI-329 is rated 3, outside sheltered storage, on carbon steel, stainless steel, cast iron, aluminum alloys, galvanized steel, copper, brass and solder; it is not meant for uncovered outdoor exposure. It carries NSN 6850-01-470-3359 and NATO stock number 6850-66-132-6100; in oil and gas it is Cortec’s additive for hydraulic system preservation.
Typical applications
- Lubricating oils
- Hydraulic oils
- Preservation oils
- Internal system components
- Lube oil skids and rundown tanks
- Gearboxes and crankcases in seasonal or indefinite lay-up
- Hydraulic systems on drilling, production and mobile equipment
- Engines, pumps and compressors between test stand and shipment
- Blended 1:9 in mineral oil as a dip or spray rust preventative for machined parts
- Lube systems of mothballed turbines and generators
How to apply VpCI-329
- Choose the ratio. Add 1 part VpCI-329 to 20 parts oil for short-term protection, 1:10 for medium-term and 1:5 for long-term lay-up. Cortec supplies a ready-mixed 1:9 blend as VpCI-329 D, which it rates for up to two years in indoor or sheltered storage.
Ratio (concentrate : oil) Concentration Term 1:20 About 5 % by volume Short-term 1:10 About 9 % by volume (VpCI-329 D is supplied at 1:9) Medium-term 1:5 About 17 % by volume Long-term - Check compatibility. Blend a sample of the actual oil at the target ratio and look for haze or separation before dosing a system. Cortec’s oil compatibility chart lists the oils it has tested; Cortec Laboratories will test an oil that is not on it.
- Dose the system. Add the concentrate to the reservoir, sump or gearbox, then run or circulate the equipment until the additive has reached every wetted surface. The system can then be left filled (wet lay-up) or drained (dry lay-up); the vapor phase inhibitors keep protecting the drained interior.
- Use as a rust preventative. For dip or spray work blend 1:9 in a naphthenic or similar mineral oil. Prepare the surface to SSPC-SP-1, clean and dry. Dip, spray with compressed-air or airless equipment, or brush until the film runs off vertical surfaces; uniform thickness is not needed. There is no drying step because the film is non-volatile, and drips can be collected and reused. Keep water out of the tank: it emulsifies the oil.
- Return to service. No removal is needed inside a lubricated system. Where a part must be clean, wash the oil film off with VpCI-414 cleaner/degreaser or an alkaline parts-washer detergent.
- Storage. Keep containers sealed and mix the drum before use, because the inhibitor package can settle in storage.
Compatibility
VpCI-329 is designed for mineral-based lubricating, hydraulic and preservation oils. Cortec’s oil compatibility chart flags it as not compatible with two of the gear and turbine oils it tested, so for synthetic or ester-based fluids in particular run a blend test or ask us to have Cortec Laboratories check the oil. On elastomers, Cortec lists VpCI-329 as compatible with PTFE and neoprene and, with a consult-Cortec note, nitrile, and as not compatible with EPDM, silicone, butyl and polypropylene. See the full oil and elastomer compatibility charts.
Where it fits in the Cortec line
VpCI-329 is the adjustable-ratio concentrate; VpCI-329 D is the same chemistry pre-blended 1:9 for dip tanks. VpCI-322 is a fixed 1:9 concentrate rated 24 months that also works in synthetic oils and can be fogged into drained cavities; VpCI-326 is the hydraulic-system additive that passes a 1-micron filter. M-529 is the choice for engine oils in intermittent service and M-531 for turbine and gearbox oils where demulsibility and a non-staining film matter. For the outside of the same machine use the oil-based coating VpCI-369. Browse the full Cortec VpCI line.
Field notes
A French gear-reducer maker had precision reducers rusting in shipment, and filling the cases with oil was costly and shipped as hazardous freight. VpCI-329 is now poured into the gearcase at only 0.3% of case volume, with CorShield VpCI-369 on the exterior: up to 48 months of protection, no oil fill and non-hazardous freight. (Cortec Case History #599)
A Cleveland, Ohio coil processor needed a rust preventive after acid pickling that pushes rinse water off the strip rather than trapping it. VpCI-329 D is sprayed onto the strip after the post-pickle rinse and squeegeed across before recoiling; 15 years of use in 4,000-gallon bulk lots, and it beat a well-known coil rust preventive in humidity testing. (Cortec Case History #658)
A private aircraft owner in New Ulm, Minnesota stored an overhauled engine in a home garage through Minnesota winters with VpCI-329 poured into the engine and the engine wrapped in Cor-Pak VpCI stretch film inside a plywood crate with silica-gel bags. It was unwrapped nearly 10 years later with no exterior corrosion. (Cortec Case History #234)
Specifications
| Dilution | Short-term 1:20 · medium-term 1:10 · long-term 1:5 (concentrate to oil) |
|---|---|
| Action | Tenacious contact film plus vapor phase inhibitors that condense on uncoated parts |
| Phases protected | Liquid and vapor |
| Specifications | Conforms to MIL-P-46002B, MIL-I-85062, MIL-C-16173D (Grade 3) |
| Stock numbers | NSN 6850-01-470-3359; NATO 6850-66-132-6100 |
| Humidity (ASTM D1748) | 600+ hours |
| Salt spray (ASTM B117) | 100 hours |
| Composition | No hazardous chromates, nitrites or phosphate inhibitors; high flash and fire points |
| Flash point (ASTM D92) | 326 °F (163 °C) |
| Viscosity | 51.4 cSt at 40 °C; 8.1 cSt at 100 °C |
| Pour point | −35 °F (−37 °C) |
| Metals | Carbon steel, stainless steel, cast iron, aluminum, galvanized steel, copper, brass, solder |
| Consultation guide rating | 3 – outside sheltered storage |
| Surface preparation (RP use) | SSPC-SP-1, dry |
| Application | Additive to oil systems; dip, spray or brush when blended 1:9 |
| Drying | None – non-volatile film, protected as soon as covered |
| Removal | Not required in lubricated systems; VpCI-414 or alkaline cleaner where a clean part is needed |
| Elastomers | Compatible with PTFE, neoprene, nitrile (consult Cortec); not compatible with EPDM, silicone, butyl, polypropylene |
| Shelf life | Up to 24 months sealed; agitate before use |
| Related grades | VpCI-329 UV (UV tracer for inspection), VpCI-329 D pre-diluted, VpCI-329 D ES, VpCI-329 SC, and VpCI-329 F food-grade variant |
| Size | 5 Gallon Pail |
| Shipping weight | 41 lb (18.6 kg) |
| Availability | In stock |
| Cortec product number | 12100031 |
Solvent Recycling Systems is an authorized Cortec® distributor. See the full Cortec VpCI line, browse the VpCI product selection guide, or contact us for volume pricing and lead times.
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