Why boiler tubes wear out
In coal-fired boilers the flue gas carries fly ash at high velocity. Where the gas path narrows or turns, the ash erodes the outer surface of superheater, reheater and economiser tubes. Soot-blower steam can cause additional local wear. When wall thickness falls below the safe limit, the tube leaks, forcing an unplanned shutdown.
What shields, sleeves and baffles do
- Bend shields: formed stainless steel covers fitted over tube bends, where erosion is usually worst.
- Protective sleeves: tubular or half-round sleeves clamped or welded over straight runs at known hot spots.
- Cassette baffles: baffle plates made as replaceable panel units that direct flue gas across tube banks and reduce bypass.
Because the shield is sacrificial, it can be replaced during a planned outage at a fraction of the cost of replacing the tube.
SS 304 or SS 310?
| Grade | Why use it | Typical zone |
|---|---|---|
| SS 304 | Good strength and corrosion resistance, economical | Lower-temperature zones |
| SS 310 | ~24–26% Cr and ~19–22% Ni give strong oxidation and scaling resistance at very high temperature | Hot gas-path zones |
Final grade selection depends on the metal temperature and gas chemistry at each location; confirm with the plant's boiler engineer.
What to specify when ordering
Tube outside diameter and bend radius, shield length and thickness, material grade, quantity, drawings or samples, and the shutdown date. Ruby Infra Projects makes half round tube shields, bend shields, protective sleeves, cassette baffles and pressure-part protection components in every grade for thermal power stations — see boiler tube protection shields, half round tube shields or send your drawing or sample details.