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.
Dust ducts wear because they must run fast
To keep fines from settling, dust extraction ducts are designed for a minimum transport velocity, and at that velocity hard dust erodes the steel wherever the flow turns or accelerates. Straight runs wear slowly; bends, branch entries, reducers, dampers and the inlet to the cyclone or baghouse wear quickly. A holed duct loses suction at the pickup points, and dust escapes at the transfer it was meant to control.
Bends and branch entries are the usual holes
In a bend, particles are thrown against the outer radius, as in bend erosion in pneumatic conveying. Where a branch joins the main at a sharp angle, the branch stream strikes the opposite wall of the main. Reducers and expansions change velocity and create local eddies. Branch entries at a shallow angle and long-radius bends reduce the wear; the geometry is worth checking before lining.
Velocity that is too high costs twice
Ducts sized or balanced with velocities well above what is needed to carry the dust erode faster and consume fan power. A balancing review — damper positions, branch sizes, leaks — can bring the velocity back to the design range and slow the wear. Too low, on the other hand, and dust settles, which is why simply slowing the flow is not a cure. Record the velocities with the wear map.
Line the fittings, not the whole system
Alumina-lined bends and fittings in IC PIPE, and wear-backed or ceramic-lined segments at branch entries, protect the points that hole; straight runs can often remain in plain steel. Rectangular ducts and transitions can be lined with tiles in IC TILE, and shaped parts in IC CUSTOM suit collector inlets and complex transitions. The trade-offs between linings for pipe-like runs are in cast basalt or ceramic-lined pipe.
The collector inlet and the fan follow the duct
The cyclone inlet and the baghouse inlet baffle take the full dust load and wear at the impact face. After the collector, the fan should see clean gas; if it wears, the collector is not separating well or the bags are damaged, and the fan casing and impeller wear as described in fan casing wear liners. Fixing the cause upstream is cheaper than lining the fan.
What to send for a dust duct lining quote
Send the duct layout with diameters or sections, bends and branch angles, the airflow and velocities at each section, the dust type and its source, temperature and humidity, the location of the holes and how often they recur. Induscoat then proposes the fittings to line; the approach for fans and ducts is on our page on pneumatic conveying, fans and ducts.