IS 802 (Part 2) : 2000Code of Practice for Use of Structural Steel in Overhead Transmission Line Towers, Part 2: Fabrication, Galvanizing,Inspection and Packing

IS 802 Part 2:2000 is the code of practice for the use of structural steel in overhead transmission-line towers — Part 2: Fabrication, Galvanizing, Inspection and Packing. It governs how a designed lattice transmission tower is fabricated, hot-dip galvanized, inspected and packed for site assembly. Design loads/members are Part 1; this is the make-and-protect part.

It sits in the transmission-tower stack:

• IS 802 Part 1 — design of transmission-line towers (loads/members) · IS 802 Part 3 — testing (full-scale tower test)
• IS 2062 — structural steel · IS 800 — steel design (general) · IS 816 — welding

A transmission tower is a bolted lattice angle structure exposed for decades in the open, often remote — so fabrication accuracy and corrosion protection decide whether the design is realised and survives:

• Fabrication — accurate marking, drilling, cutting and bend of angle members so the tower assembles on site without forcing (mis-drilled members are a classic field nightmare on remote lines); shop assembly checks
• Hot-dip galvanizing — the primary corrosion protection for a maintenance-light, decades-long exposed life; coating mass/uniformity/adhesion are critical, and galvanizing must follow fabrication (drill/cut/bend before galvanizing — field cutting/drilling destroys the coating)
• Inspection — dimensional, bolt-hole, and galvanizing quality acceptance
• Packing — bundling/marking for transport to remote sites without coating damage or member loss

The engineering point: the Part 1 design is only delivered if Part 2 is followed — fabrication accuracy governs site assembly, and galvanizing quality (done after fabrication) governs the 40+ year corrosion life. The endemic failures are mis-fabricated members that won't assemble in the field and inadequate/late galvanizing that corrodes the line prematurely.

Scenario: fabrication and protection of a designed lattice transmission tower.

Step 1 — fabricate to Part 1 design: accurate marking/drilling/cutting/bending of angles; shop trial assembly to confirm fit (catching mis-drills before the remote site).

Step 2 — galvanize AFTER fabrication: all cutting/drilling/bending complete, then hot-dip galvanize — verify coating mass/uniformity/adhesion ([IS 802 Part 2] acceptance).

Step 3 — inspect: dimensional + bolt-hole + galvanizing-quality acceptance; reject out-of-tolerance/poor-coating members.

Step 4 — pack & mark: bundle/mark for transport so nothing is lost and the coating isn't damaged en route to the remote site.

Step 5 — site assembly: towers bolt up without field cutting/drilling (which would breach the galvanizing).

Followed properly, the Part 1 design becomes a tower that assembles cleanly and lasts decades; skipped, you get field fit-up chaos and premature corrosion.

1. Field cutting/drilling galvanized members. Destroys the coating at the breach → premature corrosion; all fabrication must precede galvanizing.

2. Galvanizing before completing fabrication. Same outcome — drill/cut/bend first, then galvanize.

3. No shop trial assembly. Mis-drilled members discovered at a remote site cause major delay — verify fit in the shop.

4. Inadequate galvanizing acceptance. Coating mass/uniformity/adhesion govern the decades-long life — inspect, don't assume.

5. Poor packing/marking. Lost/mis-identified members and transport coating damage on remote-line logistics.

• IS 802 Part 1 — transmission-tower design (loads/members) · IS 802 Part 3 — full-scale tower testing
• IS 2062 — structural steel · IS 800 — steel design (general) · IS 816 — welding
• IS 277 — galvanized sheet (galvanizing context) · IS 1608 Part 1 — tensile test

IS 802 Part 2 is reaffirmed and governs the half of transmission-tower engineering that decides whether the design actually stands and lasts: fabrication accuracy and galvanizing. Towers are bolted lattice angle structures erected on remote lines and exposed for 40+ years with little maintenance, so two things dominate — members must be fabricated accurately enough to assemble in the field without forcing (shop trial assembly is the cheap insurance against a remote-site fit-up disaster), and hot-dip galvanizing, applied after all fabrication, must be of verified quality because it is the corrosion life of the line. The signature failures are field-cut/drilled members that breach the coating and corrode early, and mis-drilled steel that won't bolt up far from any workshop. Follow Part 2 — fabricate accurately, trial-assemble, galvanize last and verify it, inspect and pack properly — and the Part 1 design becomes a durable line; cut corners and the design never reaches the field intact.