{"id":1874,"date":"2026-11-10T09:00:00","date_gmt":"2026-11-10T08:00:00","guid":{"rendered":"https:\/\/procainsa.com\/?p=1874"},"modified":"2026-11-10T09:01:36","modified_gmt":"2026-11-10T08:01:36","slug":"types-industrial-corrosion-how-to-prevent","status":"publish","type":"post","link":"https:\/\/procainsa.com\/en\/types-industrial-corrosion-how-to-prevent\/","title":{"rendered":"Types of industrial corrosion and how to prevent it"},"content":{"rendered":"\n

Corrosion is one of the main causes of failure in pipelines, tanks, structures and industrial equipment. It does not always look the same: sometimes it is uniform rust that advances slowly and is visible to the naked eye, and other times it is a localised attack that perforates the metal in a few months with hardly any external signs. Knowing which type of corrosion affects an installation is the first step in choosing the right way to prevent it. <\/p>\n\n

In this article we review the most common types of industrial corrosion<\/strong>, from pitting corrosion to stress corrosion cracking and soil corrosion, what determines the corrosion resistance of a material, which corrosion tests are used and which measures work to prevent it.<\/p>\n\n

What corrosion is and why it is a problem in industry<\/h2>\n\n

Corrosion is the deterioration of a metal through its reaction with the surrounding environment. In most cases it is an electrochemical process: in one area of the metal (the anode) material is lost and in another (the cathode) a reduction reaction takes place, with an electrolyte, such as water, air humidity or soil, closing the circuit. Steel, for example, naturally tends to return to its oxide state. <\/p>\n\n

In industry, its consequences go far beyond the loss of material: product leaks, soil and groundwater contamination, unplanned shutdowns, safety risks for people and costly repairs or replacements. That is why corrosion is studied, measured and controlled as part of the integrity management<\/a> of assets. <\/p>\n\n

Types of industrial corrosion<\/h2>\n\n

Types of corrosion are classified according to the form of the attack and the mechanism that causes it. These are the ones we find most often in industrial installations. <\/p>\n\n

Uniform or general corrosion<\/h3>\n\n

The metal loses thickness more or less evenly over the whole exposed surface. It is the most common form and also the most predictable: the rate of thickness loss can be measured and the service life of the equipment calculated. It appears, for example, on unpainted steel structures exposed to the weather or inside unlined tanks. <\/p>\n\n

Galvanic corrosion<\/h3>\n\n

It occurs when two different metals are in electrical contact within the same electrolyte. The less noble metal acts as the anode and corrodes faster, while the more noble one is protected. It is typical of joints between steel and copper, brass or stainless steel, and of buried steel pipelines connected to bare copper earthing networks. <\/p>\n\n

Pitting corrosion<\/h3>\n\n

In pitting corrosion<\/strong>, a very localised attack forms small cavities on the surface of the metal while the rest remains almost intact. It is especially dangerous because the weight loss is minimal and it is hard to detect, but the pits grow in depth and can perforate a pipe or the wall of a tank. It mainly affects metals protected by a passive layer, such as stainless steel and aluminium, when that layer breaks down in the presence of chlorides, for example in seawater, brines or marine atmospheres. <\/p>\n\n

\"Pitting<\/figure>\n\n

Crevice corrosion<\/h3>\n\n

It is similar to pitting, but appears in narrow spaces where the medium becomes stagnant: under gaskets, washers, dirt deposits, sheet overlaps or threads. Inside the crevice, oxygen is depleted and the medium becomes more aggressive than outside, which accelerates the attack at that point. <\/p>\n\n

Stress corrosion cracking<\/h3>\n\n

In stress corrosion cracking<\/strong>, cracks appear through the combined action of tensile stress and a corrosive medium specific to that material. The cracks can propagate until failure without any visible loss of material, sometimes at stresses below the design values. Well-known examples are austenitic stainless steels in hot chloride media, carbon steels in caustic media or in some soils in contact with buried pipelines, and brasses in the presence of ammonia. Residual stresses from welding or forming are often enough to cause it. <\/p>\n\n

Intergranular corrosion<\/h3>\n\n

The attack advances along the grain boundaries of the metal, which become more reactive than the interior of the grains. It is characteristic of stainless steels that have been incorrectly heat treated or welded without control, in which chromium carbides precipitate near the grain boundaries and leave chromium-depleted zones. The material can lose mechanical strength even though its surface looks sound. <\/p>\n\n

Erosion-corrosion<\/h3>\n\n

It combines the mechanical wear of a moving fluid with corrosion. The fluid velocity, turbulence or suspended particles remove the protective layer of the metal and expose a fresh surface that corrodes again. It appears in elbows, reducers, pumps, valves and heat exchangers. <\/p>\n\n

Soil corrosion<\/h3>\n\n

The term soil corrosion<\/strong> covers the attack on all buried metal structures: pipelines, tanks, piles, foundations or earthing networks. Its aggressiveness depends on the soil resistivity, its moisture, its salt and chloride content, the pH, aeration and the presence of bacteria. In addition, differences between soil types along the same pipeline create differential aeration cells that concentrate the attack in the less aerated areas, such as clay soils. <\/p>\n\n

Microbiologically influenced corrosion<\/h3>\n\n

Some bacteria, such as sulphate-reducing bacteria, create conditions on the metal surface that accelerate corrosion. It is common in anaerobic soils, at the bottom of tanks with accumulated water and in industrial water systems, and usually results in deep pits under deposits. <\/p>\n\n

Stray current corrosion<\/h3>\n\n

It occurs when a direct current from outside the structure, coming from railway traction lines, trams or third-party cathodic protection systems, enters a buried pipeline and leaves it at another point to return to its source. At the point where the current leaves, corrosion can be very fast and localised. <\/p>\n\n

Type of corrosion<\/th>Where it appears<\/th>How it is prevented<\/th><\/tr><\/thead>
Uniform<\/td>Unprotected steel exposed to the weather, water or soil<\/td>Coatings, corrosion allowance and cathodic protection on buried or submerged structures<\/td><\/tr>
Galvanic<\/td>Joints between different metals<\/td>Electrically isolating the metals and avoiding small anodic areas next to large cathodes<\/td><\/tr>
Pitting<\/td>Stainless steel and aluminium with chlorides<\/td>Alloys with more molybdenum and nitrogen, chloride control and clean surfaces<\/td><\/tr>
Crevice<\/td>Gaskets, overlaps, deposits and threads<\/td>Crevice-free design, suitable gaskets and cleaning<\/td><\/tr>
Stress corrosion cracking<\/td>Stressed metals in specific media<\/td>Material selection, stress relief and control of the medium<\/td><\/tr>
Intergranular<\/td>Welded or incorrectly treated stainless steels<\/td>Low-carbon or stabilised grades and welding control<\/td><\/tr>
Erosion-corrosion<\/td>Elbows, pumps, valves and heat exchangers<\/td>Limiting fluid velocity, improving design and using harder materials<\/td><\/tr>
Soil<\/td>Buried pipelines, tanks and structures<\/td>Coating and cathodic protection<\/td><\/tr>
Microbiologically influenced<\/td>Anaerobic soils, tank bottoms and industrial water<\/td>Water treatment, cleaning and cathodic protection<\/td><\/tr>
Stray current<\/td>Buried structures near direct current systems<\/td>Interference studies, drainage bonds and insulating joints<\/a><\/td><\/tr><\/tbody><\/table><\/figure>\n\n

What determines the corrosion resistance of a material<\/h2>\n\n

The corrosion resistance<\/strong> of a material is not an absolute property of the material, but of the combination of the material and the medium it works in. A stainless steel that performs perfectly in fresh water can suffer pitting in seawater, and a carbon steel that corrodes in the open air can last for decades buried if it is well coated and cathodically protected. The most influential factors are: <\/p>\n\n