This article is featured in Infrastructure Magazine. Link here
Ensuring the ongoing infrastructure of assets subjected to constant erosion-corrosion has long been a challenge. As technology advances, novel solutions continue to be tested and brought to market, and today one of the primary methods to reduce such metal fatigue is that of protective coatings.
The following discusses the mechanisms of erosion-corrosion, how to recognise the problem and the technology behind why protective coatings can dramatically slow the process.
What is Erosion Corrosion? An Overview
Erosion corrosion is the accelerated loss of metal on a structure that’s subjected to two destructive forces: namely, erosion and corrosion. The former is caused by the mechanical effect of a fluid flowing across metal (or the metal moving through the fluid) wearing away the protective layer – the latter occurs as the corrosive element can therefore attack the exposed material below the now worn away protective layer.
The two actions combine to accelerate the rate at which the metal degrades. This deterioration leads to the premature failure of the component.
The issue can be caused by a wide variety of substances, including lime, chemicals, and abrasion (such as wear from processes, such as sandblasting).
Typical Locations for Erosion Corrosion
Some of the most common areas subjected to the phenomenon are where high flow rates are involved. Examples include:
- Tube inlet ends
- Pump impellers
- Around tube blockages
- Process tanks
- Secondary containment areas
- Pump bases
Prediction and prevention are the two most important factors to combat erosion-corrosion. Once areas have been determined, there are a variety of actions that can be taken.
For erosion-corrosion within piping, streamlining the structures to reduce turbulence will help, as will controlling the velocity of the fluid. For new applications, the use of more resistant materials is an option. However, these physical methods are not necessarily easily actioned. Therefore, the most common way forward for both piping and all rotating equipment is through the application of a protective coating that inhibits the degradation and minimises the effects of the two destructive forces.
Protective Coatings Provide a Robust Solution
The harsh conditions under which rotating equipment works demands a durable and resilient solution. The properties of coatings is a subject of continual advancement and today’s offerings provide superior protection, thanks to ceramic reinforcement.
Examples of high-quality offerings on the market designed to combat specific applications and challenges from moderate through to the most extreme of conditions include those from the market leader, ARC:
- ARC SD4i: Provides protection from extreme erosion-corrosion conditions for metals which are also subjected to aggressive chemical immersion. Can be applied by brush, roller, or spraying (airless or plural component).
- ARC S2: Designed for components subjected to moderate chemical resistance, this brush, roller, or spray application protects against erosion-corrosion and abrasion.
- ARC S7: A sprayable coating designed for high temperatures (up to 180oF/350oF) and severe chemical conditions, this low VOC, novalac vinyl ester-based coating resists a wide range of inorganic and organic acids and hydrocarbon-based chemical compounds.
- ARC S7 AR: For high temperature and abrasive applications, this novalac vinyl ester-based, ceramic-reinforced coating resists thermal cycling conditions (up to 180oF/350oF) and is applied by an airless spray system.
- ARC EG-1: A concrete grout repair resurfacer that can be rapidly applied to voids up to 12 inches and topped with other ARC coatings to protect against chemical or mechanical damage. Ideal for build-up low areas, slopes to drains, and fill spalled areas.
Combating Erosion Corrosion Requires Definitive Action
The global cost of erosion-corrosion has been estimated at over USD$2.5 trillion (Source, NACE International). Often hidden from view, this expensive and dangerous occurrence is responsible for much of the maintenance costs and unexpected downtime. Yet, with the correct protective applications, up to 35% of such incidences could be curtailed.
Chesterton is committed to providing the ultimate in such protective coatings, and market the wide range of ARC products that are relied on by industrial customers around the world to increase asset longevity.
Find out more about ARC Industrial Coating