What is the recommended surface preparation for steel in a highly corrosive zone?

Abrasive blast cleaning to Sa 2½ (near-white metal) as per IS 9162 is recommended for severe environments (Clause 5.1.1).

What type of paint system is used for protection against acid fumes?

A multi-coat system using high-build epoxy or coal tar epoxy is typically recommended for acidic environments. Refer to Table 2 for specific system details.

What is DFT and why is it important?

DFT is Dry Film Thickness, the thickness of the coating after curing. It is crucial because it directly correlates to the level of barrier protection offered by the coating; insufficient DFT is a common cause of premature failure.

Can fresh concrete be painted?

No, concrete should be fully cured (typically at least 28 days) and dry, with moisture content below 5%, before applying any impermeable coating to prevent blistering and peeling.

IS 14428

: 1997

Guidelines for painting structures in an aggressive chemical environment

CurrentSpecializedGuidelinesMaterials Science · Building Construction Practices incl. Painting, Varnishing

Download PDF BIS Portal Google

This standard provides guidelines for selecting and applying protective paint systems on steel and concrete structures exposed to aggressive chemical environments, such as those found in industrial plants. It covers the classification of corrosive environments, detailed surface preparation methods, and recommendations for suitable multi-coat paint systems to ensure long-term durability.

Guidelines for painting structures in an aggressive chemical environment

Quick Reference Values

Surface preparation standard for very severe exposure (steel)Sa 2½

Minimum Dry Film Thickness (DFT) for very severe exposure250-300 microns

Typical surface profile for abrasive blasting40-75 microns

Maximum permissible salt contamination on surface before painting< 50 mg/m²

Minimum concrete curing period before painting28 days

Practical Notes

Surface preparation is the most critical factor for coating longevity. Over 80% of coating failures are attributed to inadequate surface preparation.

Always consult the paint manufacturer's Technical Data Sheet (TDS) for specific details on pot life, overcoating intervals, and application parameters, as they can vary significantly.

Ensure compatibility between different coats in a multi-coat system (primer, intermediate, topcoat). Using a single manufacturer's system is highly recommended.