By selecting right coating, material and training, manufacturers can take adequate measures to mitigate corrosion, which annually costs Rs 2 lakh crore for Indian industry.

 

During his Independence Day speech on August 15, 2014, Prime Minister Narendra Modi gave a clarion call to the industry on ‘Zero Defect, Zero Effect’. Looking at ‘Zero Effect’ in terms of manufacturing processes is something that the Indian industry is striving to achieve. Corrosion is one of the major reasons that causes defect in any equipment and, thus, leading to disruption of production or production of defective products. Either of these has an effect not only on the company, but also on the economy.

 

It is estimated that on an average corrosion eats into about 5% of a country’s GDP – having a negative effect on the economy’s exchequer, affecting growth and sustainability. However, these figures reflect only the direct cost of corrosion, ie materials, equipment and activities of maintenance. Corrosion also has an implication on environment and leads to wastage of resources, lost production & injury of personnel. Corrosion is especially severe in manufacturing facilities that are in coastal states, where salt content is high – thus disrupting operations and requiring extensive repair & replacement of failed assets.

 

Giving a coat of protection Corrosion is the surface disintegration of metals within specific environment. There are basically three factors by which corrosion can be classified – nature of the corrodent, mechanism of corrosion, and appearance of the corroded metal. Coatings is the most commonly used aid for protection of assets from the effect of corrosion. Anti-corrosive coatings produced new materials surfaces with numerous functional properties and unique features. The importance of coating can be judged from the fact that coating can hardly be ignored in any corrosion protective scheme.

 

“Application of coatings on metal surface is perhaps the simplest method of protecting them from corrosion, oxidation, wear and abrasion. The subject of coatings is so vast that there are various categories based upon methods of application, life of the coating, function for which the coating is to be applied and so on. Organic paint coating is perhaps the simplest method of protecting metals especially steel which has enormous usage and needs protection,” says Prof A S Khanna, Department of Metallurgical Engineering and Materials Science, IIT Bombay.

 

Many ready to use coated materials, especially steels or aluminum, are available which have tremendous use in many of the day-to-day applications. Application of paints, though appears simple, needs a skilled person having knowledge of paint coatings and also on the drying properties of various coatings. Prof Khanna explains, “Long durability paint systems, used for open environments usually consist of a primer, intermediate coat and a top coat. Further, initial surface preparation plays the key role in paint durability.”

 

In India, paints market is estimated at about Rs 30,000 crore, out of which 50% is decorative and balance industrial. In industrial segment, automotive coatings accounts for 50%, marine for 15%, OEMs for 10% OEM and the balance is accounted for high performance coatings.

“High performance coatings are special functional coatings used for highly aggressive environments such as offshore structures, refineries, ships etc. Safety of paint has become a very big issue. Conventional paints are made of toxic solvents such as benzene, toluene or xylene, which are toxic. Many modern paints are now either free of such solvents or have very small amount of that. Waterborne coatings are becoming more common,” comments Prof Khanna.

 

Select right materials of construction

Using the right materials and processes can help to beat corrosion problems throughout industry. Selecting right material of construction to make equipment for capital intensive industries such as oil & gas, refining, petrochemicals, fertilizers, process plants, power, pipelines, etc, as stoppage of production (due to corrosion releated issues) could cost the manufacturer millions of rupees.

 

Prof Khanna opines, “The first methodology of corrosion protection is the right selection of materials. Though, the most corrosive structural material used today is steel and next are various stainless steels, superalloys. But this does not mean that one has to use the costlier material for corrosion protection. What it means is out of hundreds of steels, one has to select a  steel with right composition which corrodes minimum.”

 

Proper selection of materials and design are most effective in cutting the cost of corrosion and achieving low cost reliability as corrosion can be designed out of the system. The elements which promote corrosion are S and P impurities. Elements which improve corrosion resistance are Cr, Mo. “Thus, a suitable modified steel composition is chosen which corrodes minimum in a particular environment. Stainless steels have several varieties depending upon the concentration of Cr, Mo, Ni and some other alloys. Titanium is best corrosion resistant material but is 25 times more costlier than even stainless steels. thus proper material selection is the first design requirement,” says Prof Khanna.

 

Raising awareness about corrosion

To mitigate the problem of corrosion, the first step is raising the awareness about its adverse effect on the industry and then propagating means & processes to prevent and control corrosion. Fortunately, today companies are aware of the impact of corrosion on their bottom-line and hence are open to adopt corrosion control methods. “Yes there is quite increased awareness of corrosion. Perhaps it is due to several courses/training programs, annual conferences and exhibitions organised by several professional bodies,” says Prof Khanna.

In India, there are several bodies but the two most important are NACE India Section and The Society for Surface Protective Coatings, India. “Earlier, I initiated several activities through NACE India Section. Then in 2003, I started the SSPC India which now does several activities, training programs, evening technical lectures, annual conferences etc,” says Prof Khanna, who is the Chairman of SSPC India.

As a 10 year target, industry should focus at lowering losses incurred due to corrosion down to 1% of GDP as compared to current losses pinned at a high of 5% of the GDP. To achieve this target, there is a need to move from systematic procedures to systemic plans and standardisation.

 

Skilling & training

The industry and Indian Government will have to formalise a national standards for mitigating corrosion. Much information and expertise on corrosion related issues is available in the country, however, it is confined to certain pockets and areas of the industry. Government-industry partnership can be a good solution for sustaining benefits of anti-corrosion technologies being propagated through training and certification programs.

 

There should be a continuous endeavor on the part of the industry to adopt better corrosion control and mitigation measures in order to save huge direct and indirect corrosion-related expenditures. Research and development (R&D) should play a vital role in developing such technologies. Education and skill development is also important for having professional who are equipped with the requisite skills for mitigating corrosion.

 

Rapid industrial growth is expected as new developments are encouraged in the arena of corrosion control. There is a need to convince all stakeholders that controlling corrosion would not only save money, but also have a positive impact on environment.

 

Application of coatings on metal surface is perhaps the simplest method of protecting them from corrosion, oxidation, wear and abrasion. Further, initial surface preparation plays the key role in paint durability.

Prof A S Khanna, Department of Metallurgical Engineering and Materials Science, IIT Bombay