In circulating fluidised bed (CFB), pulverised-coal, supercritical and waste-heat boilers, the "four tubes" — water walls, economiser, superheater and reheater — suffer constant fly-ash erosion and alkali/sulphur corrosion. Guangzhou Sanxin undertakes boiler anti-wear and anti-corrosion spraying projects with an equipment fleet that includes imported PRAXAIR JP8000 HVOF systems, PRAXAIR arc spray sets and dozens of Miller plasma systems.
Typical Coating System for Water Walls
| Layer | Material | Thickness |
|---|---|---|
| Anti-wear / anti-corrosion layer | 45CT (NiCrTi) or cored WC wire | 0.4–0.8 mm |
| Sealer (optional) | Silicone-aluminium sealer | Penetrating |
- 45CT matches tube expansion – its thermal expansion is close to carbon steel, so the layer does not spall under cycling.
- Sacrificial protection – the nickel-chromium layer corrodes preferentially and slowly, buying years of tube life.
- On-site capability – high-power arc spray guns with dedicated wire feeds cover hundreds of square metres per outage.
- Full plant coverage – furnace chambers, cyclone inlets, back-pass banks and fluidised-bed heat exchangers can all be treated.
Beyond boilers we protect steel structures, pipelines on site and large wheels and discs with the same wire arc process.
Frequently Asked Questions
Which wire is used for boiler water-wall protection?
The industry standard is 45CT (Ni-45Cr-Ti) for coal-fired water walls, sometimes blended with WC-bearing cored wires for severely eroded zones. Both apply well by wire arc spraying and both are in our regular stock.
Can spraying be done while the boiler scaffold is up, during a normal overhaul?
Yes. Arc spray rigs are portable and we routinely coat water walls on site during a scheduled overhaul, working section by section to fit the outage window.
