U.S. Bellows, Inc. fabricated four fabric expansion joints for a gas turbine exhaust. They are 136″ L x 54″ W 12″ face-to-face. The frame and liner are fabricated from stainless steel and the fabric belt is 1-ply PTFE. The expansion joints are designed for 400°F at +/- 100″ water column. A dye penetrant examination was preformed prior to shipment.
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These fabric expansion joints were custom designed for an exhaust duct in a gas turbine facility in Europe. The 81″ x 18″ x 16″ face to face expansion joints have a integral stainless steel frame and liner with a reinforced red silicone fabric belt. The assemblies were manufactured for a 400°F operating temperature at +/-100 inches of water column pressure. The expansion joints were 100% dye pen tested before being shipped to the customer.
62″ Fabric, 42″ Hinged and 42″ Tied Universal Expansion Joints and Duct Work Designed for an Acid Plant
U.S. Bellows custom designed two 42″ tied universal expansion joints, a 42″ hinged expansion joint and a 62″ fabric expansion joint in ductwork for an acid plant in Louisiana. The assemblies had flanged and flued head bellows fabricated from 304H stainless steel. The rest of the assemblies were made from carbon steel with operating temperatures of 700°F at 10 psig. The expansion joints were dye penetrant and x-ray tested prior to shipment.
Install the FLEXXCEL HT belt material on the expansion joint frames per the BELT INSTALLATION INSTRUCTIONS. Leave section on top of duct “unbolted” at preferred splice area. Carefully trim FLEXXCEL HT belt material so the two ends “butt up” with each other.
Cut PFA film and 3″ wide FLEXXCEL material strip to equal the width of the installed belt. Staple the PFA film to the “gas side” of the FLEXXCEL material strip.
Slide the backer board under the splice area. Place the FLEXXCEL material strip over the “trimmed” HT material with the PFA film facing down. Place iron at edge of belt to begin splice. Apply pressure to iron handles during each splice. Each splice section should take approximately 5 minutes.
U.S. Bellows manufactures high-performance fabric expansion joints for industrial applications. These expansion joints often require thermal-welding (heat seal splice) in field service. Cost effective and easy-to-use heat seal irons are available from U.S. Bellows for use with FLEXXCEL materials.
The main function of a heat seal iron is to introduce enough heat to allow a proper bond between PTFE surfaces of FLEXXCEL materials. The melting point of PTFE is around 621Â°F (327Â°C). However, the setting of a heat seal iron is determined by factors like ambient temperature, thickness of bonding materials, and the surface upon which you heat seal. Applying pressure can help facilitate a good bond, but in order to achieve a correct bond, the melting point of the U.S. Bellows FLEXXCEL materials must be achieved.
- Using the U.S. Bellows drawing, organize the parts per drawing information and “match markings” on parts.
- Clean duct/flange surfaces and prepare for welding.
- Tack weld frame segments into place. If the expansion joint has a liner, make certain that the flow arrow of the expansion joint/liner is in the proper system flow direction. If liner ships loose, install frames first to allow seal weld access.
- Seal weld frames.
- Install accumulation barrier/insulation pillow — if required.
Accumulation Barriers are typically designed to fill the entire cavity of the expansion joint. Wrap the accumulation barrier around the duct/expansion joint. Pack the accumulation barrier into the cavity of the expansion joint. The liner will prevent the barrier from falling into the duct. Use thread or wire to tie across the breach opening to support accumulation barrier during installation. Remove thread or wire prior to installing the fabric belt element.
Insulation pillows are typically designed to prevent high temperatures from contacting the fabric belt material; therefore it is critical to attach the pillow in place. There are multiple ways to attach the pillow. Follow U.S. Bellows drawing for details. Pinning the pillow to the liner (as shown) or the frame are common methods of attachment.
View the full installation instruction guide for unassembled fabric expansion joints. (Continues with instructions on gaskets for single ply belts or composite belts, and fabric belts with or without factory punched holes.)
Fabric expansion joints can be shipped in a variety of conditions to allow for the most economical installation. In certain instances, it is practical to ship joints fully assembled ready to drop into place. In other cases where access is limited or joint size exceeds normal shipping constraints, the joint can be broken down into small segments and then assembled in place at the job site.
U.S. Bellows will provide the appropriate detailed storage, handling, and installation instruction based on how the expansion joint is shipped.Please use these instructions for assembled fabric expansion joints in conjunction with the approved drawing provided by U.S. Bellows.
- Confirm dimensional data per U.S. Bellows’ approved drawing.
- Confirm duct/duct flanges are in good condition.
- Confirm duct/duct flanges are lined up correctly (ensure that lateral displacement and angular movement do not exceed agreed specifications)
- Prior to installing the expansion joint frames, the opening into which the expansion joint will be installed must be inspected to verify that the opening is in accordance with design tolerances. The expansion joint is not designed to accommodate installation misalignment, unless clearly specified as a design requirement.
- Make available the following tools/equipment to simplify the installation:- Suitable/safe scaffolding
- Lifting equipment (fork lift, crane, hoist)
- Come along
- Pry Bar
1. Compare the maximum continuous operating temperature of the application against the fabric temperature rating.
2. If the application has high fly ash or dust loading, select a material with high tensile strength.
3. If the application is near a fan or where flow turbulence is expected, select a material with high flutter resistance.
4. Elastomers vary in their chemical resistance. The selected Elastomer should be checked to insure that it is compatible with the particular media it will encounter.
|Material Name||Elastomer||Temp. (F)||Service||Tensile Strength||Flutter Resistance|
* Not suitable for sustained service where oils, hydrocarbons or concentrated minerals acids are present.
Elastomers— A general name for the group of synthetic “rubber” materials that are characterized by their elastic property. These materials are also known by their commercial names as Viton®, Hypalon®, EPDM, and Chlorobutyl.
Before the development of Fluoroplastics, a group of synthetic “rubber” materials were commonly used in flue duct expansion joint applications. These materials, known as Elastomers, include Viton™, EPDM, Chlorobutyl, Hypalon™ and others.
Because of their elastic properties, the various Elastomers are built up into a multi-layered sheet reinforced with fiberglass or Aramid fabric. The finished product, 1/8″ to 1/4″ thick, is then used as a flat belt or as an integrally flanged U-shaped cross section that bolts directly to duct or equipment flanges. The inherent characteristics of flexibility, abrasion resistance, and flutter resistance translates to long service life when applied properly.
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:
- Adequate stand off height
- Adequate face to face dimension
- Inclusion of liner
- Frame material
- Belt material
- Inclusion of accumulation barrier
- Inclusion of insulation pillow
- Proper bolt hole spacing
- 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 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:
- Weld in designs are less expensive to manufacture.
- Accurate field bolt hole dimensional data can be difficult to obtain and verify.
- Welded connections can accommodate “real world” field conditions and inaccuracies that occur during installation.
|Style 100-W||Style 200-W|
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|