Evidence-first editorial standard
This guide separates observed facts, engineering assumptions and data that still require confirmation. It does not promise a universal service life or replace the exact product data and project specification.
A process fan erodes where the dusty gas turns fastest
Induced-draught, mill and exhaust fans in cement, power and steel plants move gas carrying fine abrasive dust, and the dust follows the gas into the casing at high speed. Wear concentrates at a few predictable places rather than spreading over the casing, which is what makes a targeted lining worthwhile.
The scroll and the cut-off take the stream thrown off the impeller
Gas leaving the blade tips strikes the scroll wall, and the cut-off — the tongue where the scroll meets the outlet — sees the most concentrated erosion of the casing. These stationary surfaces are the best candidates for a ceramic lining: hard alumina tiles such as IC TILE along the scroll and shaped pieces made to drawing at the cut-off, as with IC CUSTOM.
The inlet cone and the inlet box wear where the gas enters and turns
The inlet cone directs the gas into the impeller eye, and dust erodes it at the narrowest section; inlet boxes and dampers upstream wear where the duct turns. Both are stationary and can be lined, provided the lining does not change the clearance between the cone and the impeller.
Blades and the impeller are a balance question before they are a wear question
Adding mass to a rotor changes its balance and its stresses, so any wear protection on blades, shroud or hub is a decision for the fan manufacturer, with rebalancing after the work. Hard-faced or replaceable blade tips are the usual route; ceramic on the rotor only with the manufacturer’s approval. Fine-particle erosion of this kind is described in the article on ash handling and fan casing erosion.
Temperature and vibration decide the fixing method
Hot gas limits adhesives, and casing vibration tests every bond line, so the retention is chosen for both: weld-on tiles or mechanically retained elements where temperature or vibration rules out a bonded system, and adhesives such as IC BOND only within their rated temperature. The trade-offs are set out in bonded versus weldable fixing.
The data a supplier needs for a fan
Provide the fan type and duty, the gas temperature and dust load, the dust type and particle size, the casing and inlet drawings, the access doors, photographs of the worn scroll, cut-off and inlet, the current repair method and its life, and the outage window. A lined casing is then specified surface by surface, with the rotor left to the fan maker.