Rust Begins at 40
Corrosion occurs in presence of moist air. The invisible water vapour present in air leads to corrosion. Inorganic corrosion begins at 40% RH, which is the critical humidity level. The critical RH, for clean and polluted air is the same but corrosion begins faster where surfaces are exposed to polluted air in combination with high relative humidity (RH).
Kinds of Corrosion
Inorganic corrosion takes the form of rust. Military hardware and equipment in storage as War wastage reserves, tanks, missiles, ammunition, gearboxes, engines, even replacement parts and stores are highly susceptible to changes in humidity and consequently rusting and corrosion.
All military equipment is high valued and must be available for operation at any moment. Storage of steel or metal products presents major problems where air is humid and there is a big variation in temperature during the 24 hours a day causing condensation at times. In such circumstances corrosion sets in, deteriorating the quality of material.
Controlling relative humidity below 35% RH prevents rusting and corrosion - i.e. inorganic corrosion.
Means for preventing inorganic corrosion
Inorganic Corrosion Control or Prevention can be made possible through means such as plating, painting, bluing, corrosion resistant coating and dehumidification
- Inorganic : rust
- Organic : mould, mildew, fungus moisture causes corrosion. Corrosion causes waste.
Corrosion : Causes
- Outdoor relative humidity.
- Condensation leads to high humidity
- Air pollutants
Corrosion can be eliminated by controlling the moisture levels to less then 45% RH at ambient condition.
Benefits of humidity control……..
- Extends viability of stored parts and inventories
- Prevents failures
- Protects equipment when not in use
- Secures major facilities like power plants during lay-up.
Prevention of corrosion through dessicant dehumidification
Corrosion can be eliminated by controlling the moisture levels to less than 45% RH at ambient condition.
The simplest and the most cost-effective method to control humidity is to install a Bry-Air dehumidifier.
Bry-Air dehumidifiers can maintain RH as low as 1% or even lower at a constant level, regardless of ambient conditions during production, processing, packaging and storage.
Organic Corrosion and control : Organic corrosion is caused by the growth of micro organism on organic and inorganic material leading to decomposition and mechanical weakening of the products. Spoilage due to mold, mildew and fungal decay of stored textiles, leather products , batteries, tyres, stationery ,food stuff, ration,etc., result due to condensation of moisture on stored material. Temperature fluctuations are responsible for wide range of humidity leading to condensation and for organic corrosion to set in. Hygroscopic raw material storage requires humidity to be controlled between 35% to 40% RH as this prevents moisture regain and hence corrosion.