Drum End Seal Ring

Function

An effective drum end seal maintains the negative pressure (draft) inside the drum and baghouse exhaust circuit, ensuring that all combustion gas and entrained dust is captured and routed through the dust-collection system. Seal leakage allows uncontrolled hot gas to escape, heating adjacent structural steelwork, posing burn risk to personnel, and in extreme cases igniting accumulated fines. At the outlet end, leakage also allows secondary cold air infiltration that dilutes the burner hot gas, reducing drying efficiency and raising specific fuel consumption. Maintaining tight seals is therefore both a safety requirement and a direct fuel-economy measure.

Construction & quality

Spring-loaded segmented type: 12–24 individual cast-iron or carbon-graphite composite segments per ring, each mounted in a radially-sliding channel and loaded inward against the drum cylindrical face by individual coil springs (heat-resistant alloy steel, Inconel or similar). Radial float ±6–10 mm accommodates drum eccentricity. Segment contact face is graphite-lubricated or manufactured from self-lubricating carbon-graphite grade. Retaining ring and spring cage fabricated from mild steel. Operating temperature to 350 °C. Labyrinth type: 4–6 concentric rings of 3–6 mm mild steel plate, alternating between drum-side and hood-side fixing, stitch-welded to their respective flanges.

When to replace

• Visible hot gas or dust leaking around the drum inlet or outlet hood gap during operation
• Segment contact face worn to less than 8 mm remaining radial thickness on inspection
• Broken or collapsed coil springs allowing individual segments to cock, seize, or rattle
• Increased baghouse suction demand or pressure drop indicating elevated air infiltration through worn seals
• Scorch marks, carbon deposits, or paint blistering on external hood steelwork adjacent to the seal band