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He has used various types of abrasives for blast cleaning of various substrates. Carbon steel, Stainless steel and Concrete. The abrasives used are copper slag /coal slag / Garnet / Aluminum oxide. He has also used metallic abrasives like chilled Iron steel shot and Grit. The correct size and selection of abrasive is very important for good coating application. He has the experience in Shop blasting with centrifugal blast cleaning machines like wheelabrator and also portable auto-blast machines and field blast pots. He has reduced the wear and tier of auto-blast machines in one of the project by changing the ratio of Steel shot and grit. The specification had a 70:30 ratio of grit and shot and they were facing a heavy wear and tear of their auto-blast m/c parts.

The abrasive materials are costly and only by using the correct equipment and using the proper pressure usually 100PSI and appropriate distance usually about 30" from the substrate you can achieve optimum coverage of blasted surface. He has been able to save thousands of dollars in one of the projects simply by using a recycling m/c for garnet. The cost of the unit was recovered in 15 days.

There are many anti corrosive coating materials available in the market. But still A combination of Zinc silicate primer/Epoxy undercoat and Polyurethane final coat is most widely used in offshore Industries. He has over 20 years experience in coating of Offshore Platforms and the fundamental coating has been the same as above.

Blast cleaning is the best method for achieving a good surface for long term coating adhesion and protection. Usually in Open areas blast cleaning is done to Sa 2 1/2 and for internal Sa 3 is specified. Different blasting materials produce different color and texture and also different size of abrasive produce different surface profile. So for a good blast cleaning to be done you require the correct selection of abrasive depending on location / God equipment / skilled applicators and finally a good Coating Inspector.

The selection of Blast cleaning abrasive is mostly limited to what is stated on owner specification. You are also limited by the Location where the project is. As Blast cleaning abrasive is very bulky and the consumption is in a few 100 tons You should consider whether it is practical to transport the material from distance. A good material may be cheaper but transport costs may render it un economical.

The surface profile is the anchor pattern obtained on a give substrate after blasting. Usually this is 50 to 75 microns in field and 25 to 50 microns in shop blasting. The Average distance between the peak and valley is termed surface profile. It is measured with various instruments like a stylus gauge or testex tape or we can also use a comparator. For thicker coatings like glass flake epoxy a higher surface profile of 75-100 microns is recommended

Field painting is one of the toughest job for any applicator as it involves a combination of various factors and hurdles before he is able to complete the painting job to requirements. The materials usually blasted and primed are brought to field and after welding works there is extensive damage to the primer and also salt contamination is there. Unless a good secondary surface preparation is done the coating failure can occur even it has been blasted to requirement in the shop. So Field painting requires an experienced applicator to assess and do appropriate surface preparation prior to applying subsequent coats. Most of the coating projects He has handled the coating is still intact after years in service

Painting is a vast field and it is very difficult to summarize in a few words. But painting basically means the first line of defense or barrier against corrosion . And that is why all paint Manufacturers call it Protective coating. It protects the substrate from onset of corrosion.

For each type of corrosion protection requirement different type of paint or combination of paints are used. These individual paint or a combination of paint is called painting system. A typical Offshore platform project will have about 15 to 20 coating systems. Coating under insulation / Piping / Structural / tank Lining / high temp. Lines / Deck Plate etc all these will have different coating systems

Surface preparation is a key to all good coating projects. A good surface preparation even with a bad coating system will last longer than a bad surface preparation with a good coating system. Good surface preparation requires selection of right abrasive / right equipment / skilled operator and a good Inspector. Typically a coating system lasts for 20 years with proper surface preparation.
Typically a coating system lasts for 20 years with proper surface preparation.

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Has done consultancy work on coating failures Expert has consulted on getting ISO 9001 certified.