Outer Cladding Sheet

Function

By protecting the insulation from mechanical damage and moisture ingress, the cladding maintains the drum's thermal performance across its service life. It also provides a clean, closed external surface that prevents loose insulation fibres from entering the plant environment — an important occupational hygiene consideration for ceramic-fibre insulation systems. A well-maintained, undamaged cladding surface allows reliable infrared thermometer measurement of the drum outer temperature, which is a first-line diagnostic tool for insulation gaps and shell hot spots without requiring production to stop.

Construction & quality

Formed from 0.7–1.0 mm aluminised steel (Type 1 Al-Si coating) or Z275 hot-dip galvanised steel for corrosion resistance in tropical, coastal, and high-humidity operating environments. Panels are roll-formed to the drum's insulation outer radius for tight, gap-free contact. Longitudinal edges are crimped or lapped and secured with A4 stainless-steel rivets or self-tapping screws at 200 mm pitch. Circumferential panel joints are lapped in the direction of drum rotation to shed water. End closures at riding-ring stations and chute interfaces are formed to a running clearance of 5–8 mm. Panels are supplied in arc-sections of 600–900 mm width for ease of handling and on-site replacement of damaged areas without removing the entire cladding.

When to replace

• Dents, holes, or lifted panel edges allowing water ingress to the insulation layers
• Corrosion staining or rust bleed at panel overlaps in coastal or high-humidity operating environments
• Panels loosening and flapping against fixed drum structure — indicative of fastener failure
• Abnormally high outer surface temperature in a localised zone indicating exposed or moisture-saturated insulation beneath
• Visible panel distortion from a mechanical contact event such as a belt mis-track or scaffold contact