Types of Corrosion
Uniform, pitting, galvanic, crevice, concentration cell and graphitic corrosion
Corrosion can be categorized in some common types
Often combined with high-velocity fluid erosion, with or without abrasives.
Often combined with stagnant fluid or in areas with low fluid velocity.
The anodic metal develops deep pits and groves in the surface.
Crevice corrosion creates pits similar to pitting corrosion.
Often combined with stagnant fluid or in areas with low fluid velocity.
Leaves the graphite in place, resulting in a soft weak metal.
- uniform corrosion
- pitting corrosion
- galvanic corrosion
- crevice corrosion
- concentration cell corrosion
- graphitic corrosion
Uniform or General Corrosion
The metal loss is uniform from the surface.Often combined with high-velocity fluid erosion, with or without abrasives.
Pitting Corrosion
The metal loss is randomly located on the metal surface.Often combined with stagnant fluid or in areas with low fluid velocity.
Galvanic Corrosion
Occurs when two metals with different electrode potential is connected in a corrosive electrolytic environment.The anodic metal develops deep pits and groves in the surface.
Crevice Corrosion
Occurs at places with gaskets, bolts and lap joints where crevice exists.Crevice corrosion creates pits similar to pitting corrosion.
Concentration Cell Corrosion
Occurs where the surface is exposed to an electrolytic environment where the concentration of the corrosive fluid or the dissolved oxygen varies.Often combined with stagnant fluid or in areas with low fluid velocity.
Graphitic Corrosion
Cast iron loosing iron in salt water or acids.Leaves the graphite in place, resulting in a soft weak metal.
Metals and Corrosion Resistance
Common metals and their corrosion resistance to aggressive fluids as acids, bases and more
A major problem in the process industry is the corrosion of metals in pipes, valves and other parts of the constructions. This guide indicates acceptable combinations of more or less aggressive fluids and commonly used materials.
Note! Remember that corrosion is a complicated issue, depending on the combinations of materials and the fluids, the fluid temperatures, the surrounding environment and the galvanic currents in the constructions. The table below must be used with care. Always check with the producer of the material.
Note! Remember that corrosion is a complicated issue, depending on the combinations of materials and the fluids, the fluid temperatures, the surrounding environment and the galvanic currents in the constructions. The table below must be used with care. Always check with the producer of the material.
| Corrosion Resistance 1)Good 2) Be Careful 3) Not Useable | ||||||||||||
| Fluid | Metal | |||||||||||
| Carbon Steel | Cast Iron | 302 and 304 Stainless Steel | 316 Stainless Steel | Bronze | Durimet | Monel | Hasteloy B | Hasteloy C | Titanium | Cobalt base alloy 6 | 416 Stainless Steel | |
| Acetaldehyde | 1 | 1 | 1 | 1 | 1 | 1 | 1 | na | 1 | na | na | 1 |
| Acetic acid, air free | 3 | 3 | 2 | 2 | 2 | 1 | 2 | 1 | 1 | 1 | 1 | 3 |
| Acetic acid, aerated | 3 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 3 |
| Acetic acid, vapors | 3 | 3 | 1 | 1 | 2 | 2 | 2 | na | 1 | 1 | 1 | 3 |
| Acetone | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Acetylene | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | na | 1 | 1 | |
| Alcohols | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Aluminum Sulfate | 3 | 3 | 1 | 1 | 2 | 1 | 2 | 1 | 1 | 1 | na | 3 |
| Ammonia | 1 | 1 | 1 | 1 | 3 | 1 | 3 | 1 | 1 | 1 | 1 | 1 |
| Ammonium chloride | 3 | 3 | 2 | 2 | 2 | 1 | 2 | 1 | 1 | 1 | 2 | 3 |
| Ammonium Nitrate | 1 | 3 | 1 | 1 | 3 | 1 | 3 | 1 | 1 | 1 | 1 | 3 |
| Ammonium Phosphate | 4 | 3 | 1 | 1 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 2 |
| Ammonium Sulfate | 3 | 3 | 2 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 3 |
| Ammonium Sulfite | 3 | 3 | 1 | 1 | 3 | 1 | 3 | na | 1 | 1 | 1 | 2 |
| Aniline | 3 | 3 | 1 | 1 | 3 | 1 | 2 | 1 | 1 | 1 | 1 | 3 |
| Asphalt | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | na | 1 | 1 |
| Beer | 2 | 2 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Benzene (benzol) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Benzoic acid | 3 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| Boric acid | 3 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Butane | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | |
| Calcium Chloride (alkaline) | 2 | 2 | 3 | 2 | 3 | 1 | 1 | 1 | 1 | 1 | na | 3 |
| Calcium hypochlorite | 3 | 3 | 2 | 2 | 2 | 1 | 2 | 3 | 1 | 1 | na | 3 |
| Carbolic acid | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | |
| Carbon dioxide, dry | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Carbon dioxide, wet | 3 | 3 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Carbon disulfide | 1 | 1 | 1 | 1 | 3 | 1 | 2 | 1 | 1 | 1 | 1 | 2 |
| Carbon tetrachloride | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 2 | 1 | 1 | na | 3 |
| Carbonic acid | 3 | 3 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | ||
| Chlorine gas | 1 | 1 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 3 | 2 | 3 |
| Chlorine gas, wet | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 2 | 1 | 2 | 3 |
| Chlorine, liquid | 3 | 3 | 3 | 3 | 2 | 2 | 3 | 3 | 1 | 3 | 2 | 3 |
| Chromic acid | 3 | 3 | 3 | 2 | 3 | 3 | 1 | 3 | 1 | 1 | 2 | 3 |
| Citric acid | 3 | 3 | 2 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 2 | |
| Coke oven gas | 1 | 1 | 1 | 1 | 2 | 1 | 2 | 1 | 1 | 1 | 1 | 1 |
| Copper sulfate | 3 | 3 | 2 | 2 | 2 | 1 | 3 | na | 1 | 1 | na | 1 |
| Cottonseed oil | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Creosote | 1 | 1 | 1 | 1 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | |
| Ethane | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Ether | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Ethyl chloride | 3 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Ethylene | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Ethylene glycol | 1 | 1 | 1 | 1 | 1 | 1 | 1 | na | na | na | 1 | 1 |
| Ferric chloride | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 2 | 1 | 2 | 3 |
| Formaldehyde | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Formic acid | 3 | 3 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 3 | 2 | 3 |
| Freon wet | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | na |
| Freon dry | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | na |
| Furfural | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Gasoline | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Glucose | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Hydrochloric acid, aerated | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 1 | 2 | 1/2 | 2 | 3 |
| Hydrochloric acid, air free | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 1 | 2 | 1/2 | 2 | 3 |
| Hydrofluoric acid, aerated | 2 | 3 | 3 | 2 | 3 | 2 | 3 | 1 | 1 | 3 | 2 | 3 |
| Hydrofluoric acid, air free | 1 | 3 | 3 | 2 | 3 | 2 | 1 | 1 | 1 | 3 | na | 3 |
| Hydrogen | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Hydrogen peroxide | 2 | 1 | 1 | 3 | 1 | 3 | 2 | 2 | 1 | na | 2 | |
| Hydrogen sulfide, liquid | 3 | 3 | 1 | 1 | 3 | 2 | 3 | 1 | 1 | 1 | 1 | 3 |
| Magnesium Hydroxide | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Mercury | 1 | 1 | 1 | 1 | 3 | 1 | 2 | 1 | 1 | 1 | 1 | 1 |
| Methanol | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Methyl ethyl ketone | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | |
| Milk | 3 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 3 |
| Natural gas | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Nitric acid | 3 | 3 | 1 | 2 | 3 | 1 | 3 | 3 | 2 | 1 | 3 | 3 |
| Oleic acid | 3 | 3 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Oxalic acid | 3 | 3 | 2 | 2 | 2 | 1 | 2 | 1 | 1 | 2 | 2 | 2 |
| Oxygen | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Petroleum oils | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Phosphoric acid, aerated | 3 | 3 | 1 | 1 | 3 | 1 | 3 | 1 | 1 | 2 | 1 | 3 |
| Phosphoric acid, air free | 3 | 3 | 1 | 1 | 3 | 1 | 2 | 1 | 1 | 2 | 1 | 3 |
| Phosphoric acid vapors | 3 | 3 | 2 | 2 | 3 | 1 | 3 | 1 | 2 | 3 | 3 | |
| Picric acid | 3 | 3 | 1 | 1 | 3 | 1 | 3 | 1 | 1 | na | na | 2 |
| Potassium chloride | 2 | 2 | 1 | 1 | 2 | 1 | 2 | 1 | 1 | 1 | na | 3 |
| Potassium hydroxide | 2 | 2 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | na | 2 |
| Propane | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Rosin | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | |
| Silver Nitrate | 3 | 3 | 1 | 1 | 3 | 1 | 3 | 1 | 1 | 1 | 2 | 2 |
| Sodium acetate | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Sodium carbonate | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Sodium chloride | 3 | 3 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Sodium chromate | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Sodium hydroxide | 1 | 1 | 1 | 1 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Sodium hypochloride | 3 | 3 | 3 | 3 | 3 | 2 | 3 | 3 | 1 | 1 | na | 3 |
| Sodium thiosulfate | 3 | 3 | 1 | 1 | 3 | 1 | 3 | 1 | 1 | 1 | na | 2 |
| Stannous chloride | 2 | 2 | 3 | 1 | 3 | 1 | 2 | 1 | 1 | 1 | na | 3 |
| Stearic acid | 1 | 3 | 1 | 1 | 2 | 1 | 2 | 1 | 1 | 1 | 2 | 2 |
| Sulfate liquor | 1 | 1 | 1 | 1 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | |
| Sulfur | 1 | 1 | 1 | 1 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Sulfur dioxide, dry | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 2 |
| Sulfur trioxide, dry | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 2 |
| Sulfuric acid, aerated | 3 | 3 | 3 | 3 | 3 | 1 | 3 | 1 | 1 | 2 | 2 | 3 |
| Sulfuric acid, air free | 3 | 3 | 3 | 3 | 2 | 1 | 2 | 1 | 1 | 2 | 2 | 3 |
| Sulfurous acid | 3 | 3 | 2 | 2 | 2 | 1 | 3 | 1 | 1 | 1 | 2 | 3 |
| Tar | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Trichloroethylene | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Turpentine | 2 | 2 | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 1 |
| Vinegar | 3 | 3 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | na | 1 | 3 |
| Water, steam boiler feeding system | 2 | 3 | 1 | 1 | 3 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Water, distilled | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
| Water, sea | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 3 |
| Whiskey | 3 | 3 | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 3 |
| Wine | 3 | 3 | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 3 |
| Zinc chloride | 3 | 3 | 3 | 3 | 3 | 1 | 3 | 1 | 1 | 1 | 2 | 3 |
| Zinc sulfate | 3 | 3 | 1 | 1 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 2 |
- na - data not available