Coatings

In many industrial service conditions the corrosion is not so severe that the more rugged acid proof brick or tile lining is required and that simpler protective treatments such as coatings and screedings are enough for the requirement. This is understandable for light corrosives exposure such as rare or occasional spills and in plant conditions where manufacturing is more modern by automation that much of the corrosives handlings is done precisely by automatic conveyance leaving little chance for spillages. Coatings and screedings play an important role in such situations in mitigating such occasional corrosives exposure.

Coatings is similar to painting but used more in a technical sense with superior characteristics. The protective film thickness typically can range from 50 to 500 microns and rarely a 1000 micron thickness is specified due to other service demands. Coatings is more specified for equipment exteriors, structural steel, ceilings etc. There are two types of coatings – solvent based and solvent free; the former comes in lower dry film thickness and in the latter the dry film thickness is up 100 microns minimum typically.

Screedings

on the other hand, is drawn from conventional civil usage similar to renderings but better called technically in corrosion engineering as monolithic linings. They are much thicker, has more resin binder in general and as a result is more and practically impervious to the penetration of corrosive chemicals and are generally applied in thicknesses ranging from 1 to 12 mm and typically 2.5 or 3mm and 5 or 6 mm. The 2.5 or 3 mm category normally fall under self-leveling floor toppings or trowel applied screedings more for the verticals like walls. The 5 or 6 mm is specified for medium duty corrosion resistant floorings and sometimes as membranes under acid proof brick or tile linings. Screedings are very important in chemical corrosion protection as in plant flooring or in drain/ channel lining.

Epoxies and Polyurethanes suitably formulated are the most versatile polymer based products that find extensive applications in such corrosion protection applications. They are quick and easy to apply, joint less and have better aesthetic appeal besides reasonably durable when laid properly by approved experienced skilled personnel.

Experience reveals surface preparation is very vital for the performance of epoxy and polyurethane coatings and screedings. However good these products are, they will fail miserabley if executed by unskilled or fly-by agencies.