The code the tower is designed to, and the one that sends the galvanizing back to IS 4759. What each part covers, and where a fabricator's responsibility begins.
IS 802 is the code of practice for the use of structural steel in overhead transmission line towers. It is published in parts: Part 1 covers materials, loads and permissible stresses (in two sections — materials and loads, then permissible stresses); Part 2 covers fabrication, galvanizing, inspection and packing; and Part 3 covers testing.
The division matters commercially. Part 1 is the designer's document. Part 2 is ours. A tower drawing arrives already designed to Part 1; what a manufacturer is judged on is Part 2 — fabrication accuracy, galvanizing, inspection and how the steel is packed and marked for a line crew to erect.
| Part | Covers | Whose responsibility |
|---|---|---|
| Part 1, Section 1 | Materials and loads — wind, ice, broken-wire and construction load cases | Line designer / utility |
| Part 1, Section 2 | Permissible stresses in the members and connections | Line designer / utility |
| Part 2 | Fabrication, galvanizing, inspection and packing | The manufacturer — us |
| Part 3 | Testing, including full-scale tower testing | Utility, at a test station |
This is why a tender that says only “as per IS 802” is under-specified for a fabricator. What we need is the approved drawing, the bill of material, the steel grade and sub-grade, and the galvanizing requirement.
IS 802 Part 2 covers galvanizing, and like IS 2486 it delegates the detail: the coating requirement comes back to IS 4759, uniformity to IS 2633, and process practice to IS 2629. For heavy tower members that means 610 g/m², approximately 85 microns.
Our galvanizing is in-house on a 7.0 m kettle at 450–460 °C. On tower work that is not a convenience — it means fabrication accuracy and coating sit under one quality system, and a member that fails a dip test is our problem to fix rather than an argument between two vendors.
Tower loads under IS 802 Part 1 derive from the wind pressures in IS 875 Part 3. Howrah and Kolkata sit in the 50 m/s basic wind speed zone, among the highest in India — which is the environment our own structures are designed and built for.
Answered from our own line, not from the standard's cover page.
The use of structural steel in overhead transmission line towers. Part 1 covers materials, loads and permissible stresses; Part 2 covers fabrication, galvanizing, inspection and packing; Part 3 covers testing.
Part 2. Part 1 is the designer's document — the tower arrives already designed. What a manufacturer is judged on is fabrication accuracy, galvanizing, inspection and packing.
Part 2 covers galvanizing but delegates the numbers: coating to IS 4759, uniformity to IS 2633, process to IS 2629. For heavy tower members that means 610 g/m², approximately 85 microns.
Suspension, tension, angle and dead-end towers, fabricated to the approved drawing and galvanized in-house. We also fabricate substation gantries, equipment supports and distribution poles.
No — that is IS 802 Part 3 and it is done at a dedicated tower test station, normally arranged by the utility. We fabricate to the tested and approved design and certify the material and coating.
The approved drawing, the bill of material, the steel grade and sub-grade under IS 2062, the galvanizing requirement, and the delivery schedule. Send those and we will quote against them rather than against assumptions.
Tell us the standard, the coating requirement and the component, and we will confirm in writing what we can hold and how we will certify it. Galvanizing is on our own floor, so the answer comes from us and not from a sub-contractor.
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