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.
Fabric Expansion Joints > Blog Articles
This 153″ x 55″ x 21″ fabric expansion joint was custom designed for an exhaust application in a gas turbine facility overseas. It is fabricated from carbon steel with a painted frame and liner. The fabric belt is reinforced neoprene, and it’s designed for +/- 100″ water column with a temperature of -20°F to 600°F. A dye penetrant examination and paint thickness test was conducted on the assembly before being shipped.
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.
This webinar is over, view the recording at: http://info.usbellows.com/instantly-access-webinar-archives/
* Live Webinars are approved for 1 PDH credit for TX P.E.’s
This presentation will briefly touch on the basics of fabric expansion joints; however, is mainly focused on the various designs, material details, and applications. Learn how fabric expansion joints are engineered and fabricated for various applications and the many factors that influence those designs. View the abundance of materials used, including Fluoroplastic and Fluoroelastomer, and their respective capabilities. Take a journey through a Fossil Fired Power Plant and see exactly where fabric expansion joints are required.
U.S. Bellows designed a 20′ x 13′ rectangular fabric expansion joint for a plant in Louisiana. This unit was custom designed to improve the current design by eliminating the need for insulation. The fabric belt consists of five layers and the frame is fabricated from 321 stainless steel. The expansion joint is designed for 1-7/8″ lateral movement at 1350°F and ± 10 psig and was dye penetrant tested prior to shipment.
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.
Splicing of fabric expansion joints is a critical operation which needs to be performed correctly for the expansion joint splice to hold up under system operating conditions. ensureAsplice is the answer to assure that a splice is made correctly.
U.S. Bellows material is a thin, flexible, lightweight, PTFE material that clearly indicates when the proper conditions have been established for achieving a successful test splice on FLEXXCEL Fabric Expansion Joint materials. The U.S. Bellows material accomplishes this in two ways. First, a dramatic color change in the product during the splicing procedure ensures that the critical sealing temperature has been reached in the splice area. In addition, the material bonds to the expansion joint’s PTFE surface, confirming that sufficient pressure was applied during the splicing operation.
The sealing process requires that all splice components be assembled between the heat sealer and the product. As the splice heats up, the U.S. Bellows product changes from a light shade of red to a much darker shade of the red. The easily observed color change can only take place after the splice components have reached the critical sealing temperature required for PTFE products. If sufficient pressure has been applied as the color change occurs, the product will adhere to the expansion joint’s PTFE surface, confirming that the proper splicing conditions were achieved.
A successfully completed test splice utilizing the ensureAsplice material will ensure that the variables that exist during a field splice have been accounted for. The actual splice on the expansion joint can now be completed with confidence.
Variables to consider:
- Ambient conditions
- Length of extension cord
- Acceptable voltage
- Proper “backer board” usage
- Heat Seal Iron in good working condition
- Allow iron time to reach required temperature
- Be sure the green light is illuminated
- Proper amount of time used to splice
- Proper amount of pressure applied during splice
- Follow U.S. Bellows splice procedures
Shown are the items required to produce a test splice with the product
(Heat seal iron, backer board, FLEXXCEL belting material, PFA heat sealing film, ensureAsplice product, stapler, scissors, blade knife, tape measurer, marking pen)
2. Begin by placing the product on the “Backer Board” surface.
3. Overlap the 2 pieces of FLEXXCEL belt material. The overlap should be the same width as the PFA Film. Make sure the PFA film is residing between the two belt ends in the overlap splice area. Staple the PFA Film in place.
View the full instructions at: http://www.usbellows.com/fabric-catalog/ensureasplice.html
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.
When doing a single ply splice on fabric expansion joint FLEXXCEL material, U.S. Bellows recommends that a test splice be performed first . Experience has shown fluoropolymers can be processed and used at elevated temperatures without hazard if proper ventilation is used. Make certain all heat sealing is performed in well ventilated areas. Make certain the heat sealer is safely handled during use. The heat sealer temperature will reach 725°F in normal operation. Special care must be taken with the heat sealer during handling due to the high temperature.
Equipment required to splice FLEXXCEL materials:
1. Heat Seal Iron
2. Backer Board
3. FLEXXCEL belting material
4. PFA Heat Sealing Film
5. ensureAsplice product
8. Blade Knife
9. Tape Measurer
10. Marking Pen
Heat Seal Iron Operation
To operate the Heat Seal Iron, follow these instructions:
1. Plug the unit into an electrical outlet.
2. Place the Heat Seal Iron on the FLEXXCEL
3. Backer Board or another insulated surface.
4. Push the toggle switch up to the “on” position.
5. Set the temperature by turning the dial to the desired temperature. A temperature range of 700°-740°F (370-385°C) is typical for splicing FLEXXCEL materials.
The unit contains two lights, a “heat up” light and a “ready” light. The “heat up” light will remain lit until the unit reaches the set temperature, at which point the “ready” light will go on.
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.