Sudbury International fabric expansion joints are made of various materials

Proper engineering of material combinations in expansion joints results in better long-term performance.

The performance of fabric ducting expansion joints supplied by Sudbury International Engineered Products Limited depends on the severity of the environment and the selection of materials for each joint component. The manufacturer’s material selection is based on functional requirements and temperature/chemical compatibility. The Fluid Sealing Association in the United States offers the following information on how the proper engineering of material combinations results in better long-term performance, even in adverse environments.

Insulating materials and metal flanges

When Sudbury International fabric ducting expansion joints are used in a corrosive atmosphere that might not have a noticeable effect at low temperature, it could have a disastrous effect at higher temperatures still within the material’s basic heat-resistance capability. Meanwhile, systems at or below the dew point can result in highly corrosive condensates.

Elastomers and fluoroplastics are specifically compounded for gas seals and barriers and to protect Sudbury International joints against mechanical damage like erosion or abrasion. Manufacturers also use fabrics to reinforce elastomers fluoroplastics to yield the mechanical properties required to withstand the movements that ducting systems exert on fabric ducting expansion joints. Fabrics are also used in inner and intermediate layers in composite-style joints as thermal barriers and mechanical reinforcements. Fabric selection depends on compatibility with the system’s individual thermal, chemical, and mechanical requirements.

Manufacturers use insulating materials to reduce interface temperatures to levels that permit satisfactory performance and life of the gas seal layer’s elastomers and fluoroplastics. Fibreglass blankets perform well in temperatures up to 540 degrees Celsius, while ceramic blankets are rated above that level, yet have mechanical and chemical limitations.

The flexible element is connected to the ductwork with metal flanges, and metal flow liners, or baffles, are used to protect the gas seal membrane and insulation layers of the flexible element from abrasive particles in the gas stream. In addition, a liner helps to control fly-ash accumulation in the joint cavity and to reduce the flutter of the flexible element that turbulence causes. Selection of this metal depends on compatibility with the specific thermal, chemical, and mechanical requirements of the ducting system.

To learn more, contact Sudbury International.

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