Bellows / Bolsters

Cylindrical fibrous insulation bolsters for expansion joints, ducts and compensators in high-temperature service

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Bolsters are cylindrical, sausage-shaped or pillow-shaped insulation packs that fill the cavity between the flow channel and the outer fabric of an expansion joint or compensator. They shield the sensitive textile bellows from the hot medium and can also be used as standalone insulation around ducts and penetrations. Typical applications are flue gas ducts downstream of boilers, expansion joints in steam and gas turbines, piping systems in petrochemical plants, burner outlets, coolers and dryers in cement plants, and as an inner layer behind a load-carrying fabric compensator to lift its working temperature.

A bolster consists of a heat-resistant outer sleeve (glass fibre, silicate or ceramic fabric, with INCONEL or stainless-steel reinforcement depending on the target temperature) and a fibrous core of ceramic fibre (RCF), AES or silicate wool. Diameter, length and contour are produced to drawing or measurement so the bolster fits the gap tightly. Beyond thermal insulation, bolsters also contribute gas-tightness and acoustic damping.