The Expansion Joints Blog

Fabric expansion joints consist of two major components, the fabric belt material and the metal frame. The frame can connect to the ducting by welding or bolting. Each U.S. Bellows frame style has features designed to minimize the detrimental effects of temperature, movements, pressure, media, and turbulence. The U.S. Bellows team is experienced in evaluating application conditions and implementing designs that lead to long term expansion joint service.

Design alterations can include the following:

1. Adequate stand off height
2. Adequate face to face dimension
3. Inclusion of liner
4. Frame material
5. Belt material
6. Inclusion of accumulation barrier
7. Inclusion of insulation pillow
8. Proper bolt hole spacing
9. And more

Although U.S. Bellows can provide weld-in and bolt-in frame styles, wherever possible, it is strongly recommended that the expansion joint be welded in place.

Weld in Designs

Weld in design frame styles allow the expansion joint to weld directly to the duct or duct flanges. These frames styles are basic designs that can be augmented with optional components.

Benefits of weld in designs include:

1. Weld in designs are less expensive to manufacture.
2. Accurate field bolt hole dimensional data can be difficult to obtain and verify.
3. Welded connections can accommodate “real world” field conditions and inaccuracies that occur during installation.

Style 100-W	Style 200-W

Bolt in Designs

Bolt in design frame styles allow the expansion joint to bolt directly to duct flanges or equipment flanges supplied by others. These bolt in designs are generally more expensive to manufacture and are potentially more difficult to install due to hole pattern irregularities and inaccuracies. These frame styles are basic designs that can be enhanced with the optional components.

Style 100-B	Style 200-B