Power grid
Transmission line lattice towers — field repair of galvanized steel
Galvanized lattice towers in a mountainous corridor had developed white rust and local red rust at bolt heads, weld seams and cut edges. Cold spray zinc was applied by brush and roller for in-place remediation without dismantling the towers or interrupting the line, restoring sacrificial protection at the damaged points.
Why hot-dip galvanizing was not an option
Three hundred and ten towers already in service, with white rust on bolt heads and cut edges and red rust where water collects at the footings. Dismantling for re-galvanizing was not on the table — outage, land access and schedule all ruled it out — and recoating whole towers costs several times more than treating the failed points. The real constraint was logistics: material and equipment had to reach each tower position on foot, and the work had to fit inside planned outage windows.
System selection
Repairing failed points only, with no blanket overcoat. Surface prepared to Sa 2.5 where access allowed, St 3 by power tool where it did not; one or two coats of ZD96-1 to 60–80 µm dry, which is the same order as the original galvanizing it replaces. No topcoat: cold spray zinc is itself a sacrificial layer, and exposed to atmosphere it develops the same basic zinc carbonate passivation film that makes hot-dip galvanizing go dull grey. Adding a topcoat here would only hide the repair and add a second interface to fail.
How it was applied
Three-person crews: one preparing, one applying, one recording. Material went up the mountain by hand, apportioned per tower from the estimated damaged area, carried in 5 L containers. Brush and roller for the work itself, with a small brush for edges and bolt heads where a roller cannot reach. Work windows followed the planned outage schedule; on sections remaining energised, only the lower tower and foundations were touched, and clearance was confirmed with the operating unit before anyone started.
Acceptance and follow-up
Dry film thickness at every repaired point, plus a record per tower of repaired area and material batch. That record turned out to be the more useful output: once you can rank towers by how much repair each one needed, you can tell which positions are corroding faster and schedule a full recoating for those before the next inspection cycle, instead of treating all 310 the same.
Products used
Other projects
Container handling cranes — repainting without removing the booms
Boom and girder sections too large for a galvanizing bath were blast cleaned in place and coated with cold spray zinc plus a metallic sealer. Work was phased around vessel calls, with two to three girder sections released per shift, so no crane was out of service for a full day.
Tank farm — external shell and wind girder refurbishment
Twelve tanks in an inland refinery had coating breakdown at the shell course below the wind girder, where water collects. After surface preparation to Sa 2.5, cold spray zinc restored the base layer on the repaired bands; the remaining sound coating was feathered and overcoated, so only the failed bands were replaced rather than the full shell.
Not sure which grade fits your environment?
Send us the structure, the steel condition and the corrosivity category (C2 to CX). We reply with a coating system, film builds and a delivered price.