IS 1477: Practice for Painting of Ferrous Metals in Buildings

PAINTING

9/13/20243 min read

brown mountains under white clouds during daytime
brown mountains under white clouds during daytime

Introduction to IS 1477

IS 1477, The Indian Standard IS 1477 (Code of Practice for Painting of Steel Structures) is divided into two key parts, each addressing a specific aspect of the painting process to ensure the protection of steel structures from corrosion and other environmental damage:

IS 1477 (Part 1): Surface Preparation and Pretreatments

This part deals with the necessary preparation and treatments for steel surfaces before any paint is applied. Surface preparation is critical because the durability and effectiveness of the paint system largely depend on how well the surface is cleaned and treated.

Key Points of IS 1477 (Part 1):

  1. Surface Cleaning:

  • Specifies methods such as wire brushing, power tools, and blast cleaning to remove rust, mill scale, dirt, oil, and other contaminants from the steel surface.

  • The standard includes grades of surface cleanliness (e.g., Sa 2½) based on methods like dry abrasive blast cleaning, where the surface should be free from visible oil, grease, dirt, dust, and corrosion products.

  1. Degreasing and Descaling:

  • Degreasing is required to remove oils, grease, or other substances that may interfere with the adhesion of the paint. Organic solvents or alkaline cleaners are typically used.

  • Descaling may be performed by using mechanical methods such as shot blasting or chemical methods like pickling.

  1. Surface Profile:

  • The surface profile (roughness) is essential for ensuring proper adhesion of paint. The specification discusses the type of profile suitable for different paints and coatings.

  1. Pretreatment:

  • Pretreatment might involve applying a coat of primer immediately after cleaning the surface to prevent oxidation or rusting before the full paint system is applied.

IS 1477 (Part 2): Painting

This part provides detailed guidelines on how to apply paint to prepared steel surfaces. It specifies various types of paints, coatings, and the procedures for their application based on the intended service conditions of the steel structure.

Key Points of IS 1477 (Part 2):

  1. Types of Paints and Coatings:

  • Primers: Essential for providing adhesion between the steel surface and the top coat, and for offering corrosion resistance.

    Common primers include zinc-rich primers, epoxy primers, and red oxide primers.

  • Undercoats: These provide an additional layer of protection and ensure good adhesion for the finishing coat.

  • Finishing Coats: The final coat applied for aesthetic appeal and additional protection from environmental elements. Finishes can be glossy, semi-gloss, or matte, depending on requirements.

  1. Paint Application Methods:

  • Paint may be applied by brush, spray, roller, or dipping, depending on the type of paint, the size of the structure, and environmental conditions.

  • The thickness of each coat (dry film thickness) is specified, as well as the total number of coats required for adequate protection.

  1. Environmental Conditions for Painting:

  • Ideal temperature, humidity, and other conditions are outlined to ensure proper curing and adhesion of the paint. For instance, painting should not be carried out in extreme humidity or rain, as this affects the paint's ability to dry and adhere properly.

  1. Corrosion Protection:

  • Paint systems are designed based on the environmental exposure the structure will face. For example:

  • Industrial atmospheres with high pollution levels may require high-performance paint systems.

  • Marine environments near coastlines will require paint with good salt spray resistance.

  1. Inspection and Quality Control:

  • Provides guidelines for inspecting the painting work at various stages to ensure adherence to specifications. Tests might include checks on the thickness of paint, adhesion tests, and visual inspection for any defects like cracks or peeling.

  1. Maintenance of Painted Structures:

  • Regular inspection and maintenance schedules are suggested to prolong the life of the painted structure. If damage or wear is found, appropriate measures should be taken to repair or repaint the affected area.

  1. Other Important Considerations:

  • Safety Precautions: Includes safety guidelines for workers during the painting process, especially when handling chemicals, solvents, and applying paint in confined or hazardous areas.

  • Selection of Paint: The standard helps in selecting the correct type of paint system based on the structure’s exposure to weather, chemicals, or other damaging factors.

  • Compatibility of Paints: Paints from different manufacturers may not always be compatible. IS 1477 emphasizes using a system (primer, undercoat, topcoat) from a single source or ensuring compatibility between products.

  1. Application of IS 1477:

This standard is used extensively in industries such as:

  • Construction (for bridges, towers, and structural steel components).

  • Marine (ships, docks, and offshore platforms).

  • Infrastructure (pipelines, transmission towers).

  • Industrial Plants (factories, warehouses).

By following IS 1477, industries ensure that steel structures last longer, with reduced maintenance costs and extended service life, even under harsh conditions.