Code of Practice for Painting of Ferrous Metals in Buildings, Part 1: Pretreatment

IS 1477 Part 1: Scope Summary

• Scope: Covers pretreatment of ferrous metals before painting, either at factory or site.
• Purpose: To ensure good protection of ferrous surfaces by painting under general atmospheric conditions.
• Part I: Details pretreatment methods.
• Part II: Covers painting and paint schedules.
• Standardization: Aligned with international practices and Indian field conditions.
• Rounding off: Final test/analysis values rounded as per IS 2-1960, maintaining the same significant figures as specified values.

Key Points:

Pretreatment Methods (Typical Examples):

• Cleaning (removal of rust, oil, dirt)
• Surface preparation (abrasive blasting, pickling)
• Application of primers

flowchart TD
    A[Ferrous Metal Surface] --> B[Pretreatment (IS 1477 Part I)]
    B --> C[Cleaning]
    B --> D[Surface Preparation]
    B --> E[Primer Application]
    E --> F[Painting (IS 1477 Part II)]

This ensures long-lasting paint adherence and corrosion protection.

IS 1477 Part 1 - Definitions Summary

• Reference for Definitions:
  Definitions in IS 1477 Part 1 refer primarily to IS 1303-1963 (Glossary of terms relating to paints). This means all paint-related terms are as per IS 1303.

• Rounding Off Values:
  As per Clause 0.5, test or analysis results must be rounded off according to IS 2-1960:

  • The number of significant digits in the rounded value = number of significant digits in the specified value.

• International Coordination:
  The standard aligns with international practices and local Indian field practices for consistency.

Key Points:

Rounding Off (IS 2-1960) Example:

flowchart LR
    A[IS 1477 Part 1 Definitions] --> B[Use IS 1303-1963 Terms]
    A --> C[Rounding off per IS 2-1960]
    A --> D[International & Indian Practices]

Summary: Use IS 1303 for paint terms and IS 2 for rounding results to maintain compliance and clarity in testing and analysis.

IS 1477 Part 1: Surface Preparation & Rust Grades Summary

Key Points:

• Surface preparation and rust grades are crucial for paint adhesion and durability.
• Defined as per SIS 055900-1967 (Swedish Standard) with pictorial color prints.
• Four rust grades specify the extent of rusting.
• Multiple preparation grades specify how thoroughly the surface is cleaned before painting.

Rust Grades (Typical Classification):

Surface Preparation Grades (Examples):

Important Notes:

• Sand-blasting (A-1.1) produces an excellent surface but is costlier.
• Early application of paint after preparation is vital to prevent rusting.
• Phosphating can be used as a pretreatment per manufacturer's instructions.

Visual Concept (Mermaid.js):

flowchart LR
    RustGrades --> SurfacePreparation
    RustGrades[Four Rust Grades (RG1 to RG4)]
    SurfacePreparation[Multiple Preparation Grades (A-1.1, A-2, A-3, A-4)]
    SurfacePreparation --> PaintAdhesion[Effective Paint Adhesion & Life]

For detailed pictorial standards, refer to SIS 055900-1967 and IS 1477 Part 1 (1971).

IS 1477 Part 1: General Requirements for Painting Preparation of Ferrous Metals

Key Points & Specifications:

• Surface Condition (Clause 3.1):

  • Remove scale, rust, moisture, grease, salts before painting.
  • Assess environment and previous finishes for repainting.

• Surface Preparation Methods:

  • Sand-Blasting (Clause 1.1):
    Produces an excellent surface profile for paint adhesion; preferred despite higher initial cost.
  • Phosphating (Clause 7.8):
    Use proprietary aqueous/non-aqueous phosphating products as per manufacturer instructions for "in situ" treatment.

• Surface Preparation Standards:

  • Refer to SIS 055900-1967 (Swedish Standard) for pictorial rust and surface preparation grades.
  • These standards visually define cleanliness levels (e.g., St 2, St 3 for steel).

Typical Surface Preparation Grades (from SIS 055900-1967):

General Preparation Checklist:

• Inspect and clean surface thoroughly.
• Choose appropriate preparation method (sand-blasting/phosphating).
• Confirm surface profile matches paint system requirements.
• Use manufacturer guidelines for chemical treatments.

flowchart LR
    A[Start: Assess Surface] --> B{Surface Condition?}
    B -->|Rust/Scale| C[Sand-Blasting]
    B -->|Grease/Dirt| D[Cleaning]
    C --> E[Phosphating (Optional)]
    D --> E
    E --> F[Painting]

This ensures durable paint adhesion and corrosion protection under general atmospheric conditions.

IS 1477 Part 1 - Abrasives Types & Uses

Types of Abrasives (Clause 5.1)

• Metallic shot: Spherical particles from oxyacetylene cutting or industrial processes.
• Siliceous abrasives: Contain free silica (e.g., garnet, quartz, silica sand).
• Agricultural abrasives: Nut shells, corn husks, coconut shells, hardwood particles.

Specifications & Uses

Key Notes:

• Siliceous abrasives: Use silica sand max size 1.00 mm (IS:460-1962 sieve standard).
• Agricultural abrasives: Low cost, waste by-products, gentle cleaning action.
• Metallic abrasives: More aggressive, suitable for hard scale removal.

flowchart LR
    A[Abrasives Types] --> B[Metallic Shot]
    A --> C[Metallic Grit]
    A --> D[Siliceous Abrasives]
    A --> E[Agricultural Abrasives]

    B --> B1[Deep cutting, scale removal]
    C --> C1[Sharp edges, heavy cleaning]
    D --> D1[Sand, garnet, quartz - max 1mm]
    E --> E1[Grease & oil cleaning, wiping effect]

This summary aligns with IS 1477 Part 1 clauses 5.1, 5.2.1, 5.3, and 5.5 for abrasive selection and usage.

IS 1477 Part 1: Methods of Removal of Rust and Scale

Key Points from IS 1477 (Part 1):

• Rust and scale removal is essential before coating steel to prevent ongoing corrosion.
• Mechanical methods:
  • Hand scraping
  • Shot blasting
  • Flame cleaning
  • Tumbling barrels, polishing machines (Clause 6.2.6)
• Chemical methods:
  • Acid pickling with sulphuric, hydrochloric, or phosphoric acid (Clause 6.2.5.1)
  • Proprietary liquid or paste derusting compositions (Clause 7.2.1)
• Pickling must follow IS 6005-1970 procedures.
• Mill scale protects steel initially but traps moisture causing rust if left untreated.

Summary Table of Methods

Important Notes:

• Always remove temporary rust protectives before further treatment.
• Rust or scale must be removed completely before painting or phosphating.
• Mechanical and chemical methods can be combined for effective cleaning.

flowchart TD
    A[Steel Surface with Rust & Scale] --> B{Choose Method}
    B -->|Mechanical| C[Hand Scraping / Shot Blasting / Flame Cleaning]
    B -->|Chemical| D[Acid Pickling / Proprietary Compositions]
    C --> E[Clean Surface]
    D --> E
    E --> F[Apply Protective Coating / Phosphating]

For detailed pickling procedure, refer to IS 6005-1970.

Handling Factory Pretreated and Primed Surfaces (IS 1477 Part 1)

Key Specifications & Procedures

• Inspection: Carefully inspect factory pretreated/primed surfaces for damage or corrosion.
• Cleaning: Damaged areas must be degreased using clean solvent swabbing.
• Corrosion Removal: Remove corrosion products thoroughly.
• Touch-up: Apply a wash or etching primer on chemically pretreated surfaces before priming.
• Priming: Rectified areas should receive an appropriate primer coat immediately.
• Subsequent Coats: Apply putty and finish coats after primer, preferably on-site after cleaning damaged parts.

Important Clauses

Best Practice Flow

flowchart TD
    A[Factory Pretreatment & Priming] --> B[Transport & Storage]
    B --> C[Inspection at Site]
    C --> D{Damage Found?}
    D -- Yes --> E[Degrease & Remove Corrosion]
    E --> F[Apply Wash/Etching Primer]
    F --> G[Apply Primer Coat]
    D -- No --> H[Proceed with Finish Coats]
    G --> H

Summary: Factory pretreatment and priming ensure durability. Damaged areas must be cleaned, corrosion removed, and primed immediately to maintain protection and reduce site preparation.

Importance of Early Application of Paints (IS 1477 Part 1)

• Early painting is critical to protect steel surfaces from corrosion. Delays allow rust, scale, and contaminants to form, reducing paint adhesion and durability.
• Surface preparation quality directly affects paint life. IS 1477 Part 1 defines:
  • Four grades of rusting on steel surfaces.
  • Corresponding surface preparation grades to ensure proper paint adhesion.
• Key factors before painting (Clause 3.1):
  • Metal surface condition: free from rust, scale, moisture, grease, salts.
  • Environmental exposure: atmospheric conditions impact paint choice and schedule.
  • Previous paint finish: important for maintenance repainting.
• Design considerations (Clause 4.1):
  • Surfaces must be accessible and suitable for priming.
  • Early application maximizes protective life of paint coatings.

Summary Table: Surface Condition vs Preparation Grade

flowchart LR
    A[Steel Surface] --> B[Surface Condition Assessment]
    B --> C{Rust Grade}
    C -->|Grade 1| D[Blast Cleaning]
    C -->|Grade 2| E[Wire Brushing + Solvent Cleaning]
    C -->|Grade 3| F[Power Tool Cleaning]
    C -->|Grade 4| G[Blast Cleaning + Rust Removal]
    D --> H[Early Paint Application]
    E --> H
    F --> H
    G --> H
    H --> I[Maximize Paint Life & Protection]

In essence: Early paint application on properly prepared surfaces per IS 1477 Part 1 ensures long-lasting corrosion protection.

IS 1477 Part 1: Safety and Precautions Summary

Key Safety Clauses:

• Clause 7.2:
  Take proper fire and explosion precautions before starting work.

• Clause 6.2.4.1 & Appendix B:

  • Use non-sparking tools (wire-brushes, chipping hammers, scrapers) in inflammable areas (e.g., near petrol tanks).
  • Follow special precautions against static electricity during sand-blasting in flammable atmospheres.

• Clause 6.2 & A-6.2:

  • Use a filtered supply of cool, dry air for bleeding (preferably from a separate auxiliary compressor).
  • Ensure oil and water removal by installing drip legs and final separators near blasting stations to prevent moisture and contamination.

Important Precautions Checklist:

• Use non-sparking tools in flammable zones.
• Prevent static electricity buildup during sand-blasting (see Appendix B).
• Maintain dry, oil-free compressed air supply with proper filtration and drainage.
• Conduct fire and explosion hazard assessments before work.

Diagram: Air Supply Filtration System for Sand-Blasting

flowchart LR
    Compressor --> DripLegs[Drip Legs (Water Removal)]
    DripLegs --> OilSeparator[Oil Separator]
    OilSeparator --> FinalSeparator[Final Separator (Near Blasting Station)]
    FinalSeparator --> BlastingStation[Blasting Station (Clean Dry Air)]

Summary: IS 1477 mandates strict control of air quality, use of non-sparking tools, and static electricity precautions to ensure safety in inflammable environments during sand-blasting.

IS 1477 (Part 1) - 1971: Sand-Blasting Equipment & Working Principles

Key Specifications & Working Principles

• Working Pressure & Flow:

  • Air pressure: 5 to 6 kgf/cm²
  • Air displacement: 5.6 to 7 m³/min
  • Coverage: 25 to 30 m²/nozzle-hour (commercial blasting area)

• Equipment Components (Fig. 1):

  • Abrasive Storage Hopper
  • Abrasive Control Valve
  • Sand Hose Connection
  • Nozzle Filling Valve (for continuous type)
  • Upper & Lower Compartments (for abrasive control)

• Nozzle Distance from Surface (Clause 3.2):

  • Closer distance → higher particle impact, concentrated blast
  • Further distance → wider blast pattern, larger coverage
  • Optimum distance varies by job; determined by trial and error

Summary Table

Diagram: Sand-Blasting Equipment Essentials

graph LR
  A[Abrasive Storage Hopper] --> B[Abrasive Control Valve]
  B --> C[Sand Hose Connection]
  C --> D[Nozzle]
  D --> E[Surface to be blasted]

Note: Maintain correct nozzle distance and air pressure for effective blasting and surface cleanliness.

Precautions Against Static Electricity in Sand-Blasting (IS 1477 Part 1, Appendix B, Clause 6.2.4.1)

• Cause: Air and abrasive flowing through the hose generate static charges.
• Critical in: Inflammable areas (e.g., oil tank farms, petroleum tanks).

Key Precautions:

• Grounding:

  • Nozzle and hose must be grounded with separate ground wires.
  • All metal parts prone to sparking must be electrically bonded and grounded.
  • Effective bonding between tank, sand-blast nozzle, sand hopper, and air compressor is essential.

• Reason:

  • Sparks originate from static electricity at the nozzle impact point, not from sand impact or heat.
  • Silica sand at ~0.6 kgf/cm² pressure generally does not spark, but static discharge can occur.

Operational Parameters (Appendix A, Clause 6.2.1):

• Air pressure: 5 to 6 kgf/cm²
• Air displacement: 5.6 to 7 m³/min
• Output: 25 to 30 m² blasted area per nozzle-hour

Summary Table:

flowchart LR
    A[Air & Abrasive Flow] --> B[Static Charge Generation]
    B --> C{Inflammable Area?}
    C -- Yes --> D[Ground Nozzle & Hose]
    C -- No --> E[Standard Precautions]
    D --> F[Bond Tank, Nozzle, Hopper, Compressor]
    F --> G[Prevent Sparking]

In brief: Always ensure proper grounding and bonding of all equipment parts during sand-blasting in inflammable areas to prevent static sparks and potential fire hazards.