Fabric Expansion Joint: An assembly that utilizes a fabric belt element to allow for the movement of ductwork, as opposed to a metal expansion joint which allows for the movement by means of convoluted metal bellows.
Cold Shell: A duct that is internally insulated with refractory material.
Hot Shell: A duct that is externally insulated.
Fabric Over Metal: A design that allows for a fabric expansion joint to be installed over a metal expansion joint.
Vulcanize: A process of heating and adding sulfur to an elastomeric material. Vulcanizing is required in the manufacturing and splicing of elastomers.
Breach: The opening in the duct where the fabric expansion joint is installed.
Face-to-Face: See Span.
ID: Inside Duct Dimension.
OD: Outside Duct Dimension.
Standoff: The distance of the fabric belt from the gas stream. The proper standoff allows belt cooling in high temperature applications and prevents the belt from being pulled into the gas stream in negative pressure.
Gasket: A non-porous deformable material that is installed between the belt attachment flange and the fabric belt. The gasket allows a gas tight seal when the back-up bar clamping action is applied.
Insulation Tape: A thin layer of insulating material, usually woven fiberglass, that is installed between the belt attachment flange and the fabric belt. In certain cases, insulation tape is also used between the fabric belt and the back-up bar. The purpose of the tape is to prevent the conduction of high temperatures to the fabric material where it is clamped.
Insulation Pillow: In applications where the gas stream temperature is greater than the fabric belt.
Liner: The liner is metal plate or plates that are designed to protect the fabric belt from the gas stream while at the same time allowing the expansion joint movement. The liner can be bolted, welded, floating, or integral to the standoff frame. A single liner is connected to the upstream side of the expansion joint. In some cases, a second “telescoping” liner is used on the downstream side.
