Code of Practice for Use of Structural Steel in Overhead Transmission Line Towers, Part 2: Fabrication, Galvanizing,Inspection and Packing

Scope Summary - IS 802 Part 2

• Clause 2.2.1: Drawings must detail all design dimensions, including member length, slopes, section sizes, bend/gauge lines, bolt details (diameter, length, number), gusset plate sizes, hole positions, and relative member locations.

• Clause 10.6: Manufacturer must supply all gauges and templates required for inspection.

• Clause 5.4 & Table 1 (Bolt Spacing & Edge Distance):

• Clause 5.9: Bolt gauge distances in angle flanges should follow Table XXXI of SP:6(1)-1969.

Key Points:

• Ensure minimum bolt spacing and edge distances as per Table 1.
• Provide complete detailed drawings for fabrication and inspection.
• Use standard gauges/templates supplied by the manufacturer for quality control.

flowchart TD
    A[Design Drawings] --> B[Include all dimensions & bolt details]
    B --> C[Manufacturing]
    C --> D[Supply gauges/templates]
    D --> E[Inspection]
    E --> F[Verify bolt spacing & edge distances per Table 1]

This ensures compliance with IS 802 Part 2 for steel structure fabrication and inspection.

IS 802 Part 2: Plan and Drawing Key Points

• Complete Design Dimensions (Clause 2.2.1):

  • Member length, section sizes, slope factors/triangles
  • Bend lines, gauge lines, hole positions
  • Diameter, length, number of bolts, washers, spacers
  • Gusset plate sizes and relative member locations

• Standards for Drawings (Clause 2.1):

  • Follow IS 696-1972 (General arrangement and details of steel structures)
  • Follow IS 962-1967 (Technical drawings - conventions)

• Shop Drawings (Clause 2.3):

  • Must include:
    • Member sizes, lengths, and marks
    • Hole positions, gauge and bend lines
    • Edge distances, clipping, notching details

Typical Drawing Specifications Summary

flowchart TD
    A[Start: Design] --> B[Prepare General Arrangement Drawing]
    B --> C[Show Dimensions & Member Details]
    C --> D[Prepare Shop Drawings]
    D --> E[Include Hole Positions, Bend Lines, Notching]
    E --> F[Fabrication & Assembly]

Note: Always ensure drawings comply with IS 696 and IS 962 for clarity and standardization.

IS 802 Part 2: Material Quality Control - Key Points

• Identification (Clause 3.2):

  • Different steel grades must be clearly marked for correct placement in towers.

• Quality Assurance (Clause 10.7):

  • Manufacturer must use correct steel grade.
  • Inspector may order lab testing to verify steel quality.

• Inspection Tools (Clause 10.6):

  • Manufacturer to provide all necessary gauges and templates for inspection.

• Straightening (Clause 4.1):

  • Materials must be straight, free from twists, and flattened by pressure only.
  • Hammering is prohibited.
  • Sharp bends cause rejection.
  • Adjacent parts must have close contact within specified tolerances.

Typical Quality Control Checks (per IS standards):

Summary Diagram of Material QC Process:

flowchart TD
    A[Steel Material Receipt] --> B[Marking & Identification]
    B --> C[Visual Inspection]
    C --> D{Straightening Needed?}
    D -- Yes --> E[Pressure Straightening Only]
    D -- No --> F[Proceed to Fabrication]
    E --> F
    F --> G[Lab Testing (if required)]
    G --> H[Approval for Use]

This ensures correct grade, proper condition, and traceability of steel before fabrication.

IS 802 Part 2: Operations in Fabrication - Key Points

1. Material Identification (Clause 3.2)

• When multiple steel grades are used, markings must be clear to ensure correct placement in towers.
• This prevents mix-ups during fabrication and erection.

2. Fabrication Tolerances (Clause 6.1)

• Fabrication tolerances must comply with Clauses 6.2 to 6.5.
• For unspecified tolerances, refer to IS 7215-1974 (General tolerances for steel structures).

Typical Fabrication Tolerances (from IS 7215-1974):

3. Additional Specifications

• Fabrication includes cutting, drilling, welding, and assembly.
• All operations should ensure dimensional accuracy and surface quality.
• Galvanizing and inspection procedures follow after fabrication (Part II).

flowchart TD
    A[Material Receipt] --> B[Marking & Identification]
    B --> C[Cutting & Shaping]
    C --> D[Drilling & Punching]
    D --> E[Welding & Assembly]
    E --> F[Inspection & Quality Control]
    F --> G[Galvanizing & Packing]

Summary: Proper material marking and adherence to tolerance limits per IS 802 and IS 7215 are essential for quality fabrication.

Bolting and Hole Specifications as per IS 802 Part 2 (1978)

1. Hole Dimensions (Clause 5.3):

• Holes must be cylindrical (no oval/lobed shapes).
• Hole diameter = Bolt diameter + 1.5 mm.

2. Bolt Spacing and Edge Distance (Clause 5.4, Table 1):

3. Bolt Gauge Distances in Angle Flanges (Clause 5.9):

• Follow Table XXXI of SP:6(1)-1969 for bolt gauge distances in angle flanges.

4. Hole Positioning near Bend Lines (Clause 4.4.3):

• Holes near bends must be drilled/punched after bending using templates/jigs to maintain relative positions.

Quick Formula Summary:

• Hole diameter = Bolt diameter + 1.5 mm
• Minimum spacing and edge distances as per Table 1 above.

flowchart TD
    A[Bolt Diameter] --> B[Hole Diameter = Bolt Dia + 1.5 mm]
    B --> C[Check Bolt Spacing & Edge Distance]
    C --> D{Bolt Spacing & Edge Distance from Table 1}
    D --> E[Spacing OK?]
    E -->|Yes| F[Proceed with Bolting]
    E -->|No| G[Adjust Design]

This ensures proper load transfer and avoids tearing or deformation around bolt holes.

Fabrication Tolerances as per IS 802 Part 2

• Hole Diameter Tolerance (Clause 6.2):
  Maximum allowable difference in diameter on two sides of a plate/angle = 0.8 mm
  (i.e., taper in punched holes ≤ 0.8 mm diameter)

• Cumulative Hole Tolerance (Clause 6.3):
  Tolerance between consecutive holes = ± 0.5 mm

• Straightening and Flattening (Clause 4.1):

  • Material must be reasonably straight, free from twists.
  • Straightening by pressure only; hammering not allowed.
  • Adjacent assembled surfaces must be in close contact.
  • Sharp bends cause rejection.

• General Tolerances:
  For unspecified tolerances, refer to IS 7215-1974.

Summary Table of Key Tolerances

flowchart LR
    A[Start Fabrication] --> B{Check hole diameter}
    B -->|Difference ≤ 0.8 mm| C[Accept Hole]
    B -->|Difference > 0.8 mm| D[Reject Hole]
    C --> E{Check cumulative hole tolerance}
    E -->|Within ±0.5 mm| F[Proceed]
    E -->|Outside ±0.5 mm| D
    F --> G{Check straightness}
    G -->|No twists/sharp bends| H[Accept Member]
    G -->|Twists/sharp bends| D

This ensures structural integrity and proper assembly fit as per IS 802 Part 2.

IS 802 Part 2 (1978) - Marking and Identification Key Points

• Clause 11.4: Each bundle/package must be appropriately marked to avoid losses/damages during transit.
• Marking should be clear, durable, and visible on the packaging.
• Markings typically include:
  • Manufacturer's name or trademark
  • Bundle/package number or identification code
  • Quantity and weight
  • Destination or consignee details
  • Handling instructions (if any)

Additional Relevant Specifications:

• Clause 10.6: Manufacturer must supply all gauges and templates for inspection.
• Clause 2.2.1: Drawings must clearly show all design dimensions, member sizes, bolt sizes, hole positions, etc., aiding proper identification.

Recommended Marking Format (Example)

flowchart TD
    A[Manufacturing] --> B[Marking Bundle]
    B --> C{Marking Includes}
    C --> D[Manufacturer Name]
    C --> E[Bundle Number]
    C --> F[Quantity & Weight]
    C --> G[Destination Details]
    C --> H[Handling Instructions]
    B --> I[Inspection with Gauges/Templates]
    I --> J[Dispatch]

Summary: Proper marking per IS 802 Part 2 ensures traceability, safe handling, and reduces transit damage risks.

IS 802 Part 2: Shop Erection Key Points

1. Shop Drawings (Clauses 2.2.1 & 2.3)

• Must include:
  • Member sizes, lengths, and marks
  • Hole positions, edge distances, gauge & bend lines
  • Amount of clipping, notching
  • Bolt details: diameter, length, number, washers, spacers
  • Gusset plate sizes and hole positions
  • Relative location of members and slope factors

2. Shop Erection Procedure (Clause 8.1)

• Temporary erection of steelwork in horizontal or vertical position
• Complete one tower of each type including leg extensions
• Purpose: Check dimensional accuracy before mass fabrication

3. Key Specifications

• Accurate alignment and fit-up verified during temporary erection
• Any discrepancies corrected before proceeding to final fabrication

Summary Table: Shop Erection Checklist

flowchart TD
    A[Prepare Shop Drawings] --> B[Temporary Shop Erection]
    B --> C[Check Accuracy of Members]
    C --> D{Accurate?}
    D -- Yes --> E[Proceed to Mass Fabrication]
    D -- No --> F[Correct Errors & Recheck]
    F --> B

This process ensures precise fabrication and fit-up of steel components as per IS 802 Part 2.

IS 802 Part 2: Painting and Galvanizing Key Points

Painting (Clause 9.1)

• Surface Preparation: As per IS 1477 (Part I)-1971 (pretreatment).
• Primer & Finishing Coats: As per IS 1477 (Part II)-1971.
• Process: Clean surface → Apply primer → Apply finishing coats.
• Purpose: Protect steel from corrosion, improve durability.

Galvanizing (Clause 9.2)

• Bolts & Fasteners: Hot-dip galvanized per IS 5358-1969.
• Structural Members: Hot-dip galvanized per IS 4759-1968.
• Spring Washers: Galvanized as per IS 1573-1970.
• Coating Thickness: Typically 50-85 microns for structural steel.
• Purpose: Provide corrosion resistance by zinc coating.

Summary Table

Important Notes:

• Ensure shop erection (Clause 8.1) for dimensional accuracy before mass fabrication.
• Follow tolerances as per IS 802 Part 2 for fabrication.
• Galvanizing must be uniform and free from defects like blisters or bare spots.

flowchart TD
    A[Steel Member] --> B[Surface Preparation (IS 1477 Part I)]
    B --> C[Primer Coat (IS 1477 Part II)]
    C --> D[Finishing Coat (IS 1477 Part II)]
    A --> E[Hot-Dip Galvanizing]
    E --> F[Bolts & Fasteners (IS 5358)]
    E --> G[Structural Members (IS 4759)]
    E --> H[Spring Washers (IS 

IS 802 Part 2 – Inspection Key Points

• Inspection Access (Clause 10.1):
  Inspectors must have free access to all fabrication areas during reasonable hours to verify compliance with the standard.

• Manufacturer's Responsibility (Clause 10.6):
  All necessary gauges and templates for inspection must be provided by the manufacturer to facilitate accurate checking.

Inspection Specifications Summary

Typical Inspection Tools Include:

• Templates for checking member dimensions and bolt hole sizes
• Gauges for weld size, thickness, and alignment
• Measuring instruments for length, angle, and straightness

Inspection Workflow (Mermaid Diagram)

flowchart TD
    A[Start Inspection] --> B[Access Fabrication Area]
    B --> C[Use Gauges/Templates Provided]
    C --> D[Check Dimensions & Fabrication]
    D --> E{Conforms to IS 802?}
    E -- Yes --> F[Approve Fabrication]
    E -- No --> G[Reject/Rectify]
    F --> H[End Inspection]
    G --> H

Note: IS 802 Part 2 emphasizes manufacturer responsibility for providing inspection aids and inspector’s right to verify fabrication quality.

IS 802 Part 2 (1978) — Packing and Dispatch Key Points

• Clause 11.4 (Packing):

  • Packings must prevent losses/damages during transit.
  • Each bundle/package must be clearly and appropriately marked for identification.

• Clause 11.3 (Small Items Packing):

  • Bolts, nuts, washers, and attachments are to be packed in double gunny bags.
  • Each bag must be accurately tagged with content details.

Summary Table for Packing

Best Practices (Engineering Insight)

• Use shock-absorbent materials (e.g., wooden crates, cushioning) for fragile parts.
• Mark packages with handling instructions (e.g., "Fragile," "This Side Up").
• Ensure moisture-proof packing for galvanized items to prevent corrosion.

flowchart TD
    A[Fabrication Complete] --> B[Packing]
    B --> C{Item Type?}
    C -->|Bolts, Nuts, Washers| D[Double Gunny Bags + Tagging]
    C -->|Structural Bundles| E[Protective Packing + Marking]
    D --> F[Dispatch]
    E --> F

This ensures safe transit and clear identification per IS 802 Part 2 requirements.

IS 802 Part 2: Guarantee and Compliance Key Points

• Clause 10.3 (Guarantee):
  Manufacturer must guarantee compliance with IS 802 Part 2 provisions if requested by purchaser.

• Clause 10.6 (Inspection Tools):
  Manufacturer shall supply all necessary gauges and templates for inspector's verification.

• Clause 11.4 (Packing):

  • Packing must prevent damage/loss during transit.
  • Each bundle/package must be clearly marked for identification.

Summary Table for Compliance

Practical Notes:

• Ensure documentation of guarantee is clear and signed.
• Provide calibrated gauges/templates to inspectors.
• Use robust packaging materials (e.g., wooden crates, metal bands) and mark bundles with product ID, weight, and handling instructions.

flowchart TD
    A[Manufacturer] --> B[Guarantee Compliance]
    B --> C[Provide Gauges/Templates]
    B --> D[Package & Mark Bundles]
    D --> E[Transit]
    E --> F[Inspection & Acceptance]

This ensures traceability and quality assurance per IS 802 Part 2.