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Guide to Selecting an Elastomeric Belt Material

November 12th, 2012 Comments off

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
FLEXXCEL RH125 Hypalon 225 Dry Medium Medium
FLEXXCEL RE125 EPDM 300 Wet* Medium Medium
FLEXXCEL RE25 EPDM 300 Wet* High High
FLEXXCEL RC125 Chlorobutyl 300 Dry Medium Medium
FLEXXCEL RC25 Chlorobutyl 300 Dry High High
FLEXXCEL RVF25 Fluoroelastomer 400 Wet Medium Medium
FLEXXCEL RVF25 Fluoroelastomer 400 Wet High High
FLEXXCEL RVF25M Fluoroelastomer 400 Wet High High

* Not suitable for sustained service where oils, hydrocarbons or concentrated minerals acids are present.

60″ Dia. Pressure Balanced Elbow Expansion Joint for a Power Generation Plant

November 5th, 2012 Comments off

Pressure Balanced Elbow Expansion Joint

This pressure balanced elbow expansion joint is 60″ diameter and 240″ overall length and was custom designed for a power generation plant in South Carolina. It was fabricated from carbon steel with 304 stainless steel bellows. The expansion joint was designed for an axial compression of 1″, lateral of 1″, and 100 PSIG at 100°F.

Flexxcel Elastomeric Materials for Fabric Expansion Joints

October 28th, 2012 Comments off

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.

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Fabric Expansion Joints Custom Designed for an Offshore Oil Extraction and Natural Gas Project

October 20th, 2012 Comments off

Round Fabric Expansion Joint
These fabric expansion joints were custom designed for an offshore oil extraction and natural gas project. They are 105″ dia. x 24″ O.A.L. 309 stainless steel was used for the duct, 310 for the liners, 316 for the covers, 321 for the studs, 309 for the flanges. The fabric belt was a three layer belt with an inner layer of glass cloth, a layer of KO wool and an outside layer of reinforced PTFE. The expansion joints were designed for 1 psig at a temperature of 1100°F. They The were designed for 4″ axial compression, a 1″ extension, and a 0.5″ lateral offset. All welds were dye penetrant examined.

Application Specific Materials for Flexxcel Fluoroplastic Expansion Joints

October 15th, 2012 Comments off

Fabric belt material selection is a critical factor in the successful design of each fabric expansion joint. View the different application specific materials for our Flexxcel Fluoroplastic joints.

Flexxcel HC40 For Highly Corrosive Applications
Flexxcel HC40 for Highly Corrosive Applications

*colors used to differentiate layers

  • LFP™ is an all PTFE material that is flexible, resists tearing and has superior flexing capabilities compared to other PTFE products.
  • Water StampBecause this is an all-PTFE product with excellent mechanical capability, no compromising reinforcement that can be chemically attacked is needed.
  • Regardless of the chemical exposure, LFP™ eliminates concern for chemical attack. This has been proven in laboratory and industrial service where, in all cases and regardless of chemical environment, LFP™ has retained all of its physical properties.
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    Read more on Application Specific Materials for Flexxcel Fluoroplastic Expansion Joints

    Frame Designs for Fabric Expansion Joints

    August 27th, 2012 Comments off

    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
    Fabric Expansion Joint Movement Illustration Fabric Expansion Joint Movement Illustration

    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
    Fabric Expansion Joint Movement Illustration Fabric Expansion Joint Movement Illustration

    118″ Universal Expansion Joint for Steam Service

    August 20th, 2012 Comments off

    118" Universal Expansion Joint for Steam Service

    This 118″ diameter tied universal expansion joint was designed for steam service in a power plant in Alaska. The expansion joint duct, tie rods and cover are fabricated from carbon steel with 304 stainless steel bellows and liner. The overall length is 225″. It was designed for 250°F at 7.25 PSIG and 3.52″ of lateral movement. Dye-penetrant testing, spot x-ray and an air and soap test were performed on the universal expansion joint assembly prior to shipping.

    Find Your Fabric Expansion Joint by Applications

    August 13th, 2012 Comments off
    High Temperature Dirty Flue Gas
    Similar Applications: Fossil Fired Power Plant (Gas Recirculation System), Pulp and Paper Plant (Recovery Boiler to Precipitator), Refinery (Turbo-Expander to CO Boiler and CO Boiler to Precipitator), Cement Plan (Clinker Cooler to Heat Exchanger)

    Typical Conditions: 650°F to 850° operating temperature, -10″ to -25″ WG pressure, fuel gas media with heavy particulate, boiler growth contributes to large axial or lateral expansion joint movements depending on the orientation of the joints

    Common Design Features:

    Fabric Belt: Un-insulated fabric material. (FLEXXCEL HD7)

    Accumulation barrier: Fills expansion joint cavity to minimize the accumulation of particulate.

    Liner: Flow liner to retain the accumulation barrier and protect the belt from abrasion.

    Recommended Expansion Joint Designs: Style 200W, 100W, 300W, 600W, and 700W

    Fabric Expansion Joint Movement Illustration
    Turbulent Air
    Similar Applications: Pulp and Paper Plant (Primary Air to Recovery Boiler)

    Typical Conditions: Ambient temperature, 40″ to 50″ WG pressure, clean air movement mainly limited to vibrations

    Common Design Features:

    Fabric Belt: At fan locations, a flutter resistant fabric belt material should be used. (FLEXXCEL FF1)

    Accumulation barrier: Bolt-in design for attachment to equipment or duct flanges.

    Liner: Flow liner to reduce turbulence/flutter of fabric belt material.

    Recommended Expansion Joint Designs: Style 200B, 100B, 300B, 400B, and 500B

    Fabric Expansion Joint Movement Illustration
    High Temperature Clean Air
    Similar Applications: Fossil Fired Power Plant (Air Heater to Coal Pulverizers), Cement (Clinker Cooler to Heat Exchanger)

    Typical Conditions: 600°F to 750°F operating temperature, 5″ to 80″ WG pressure, clean air media, boiler growth contributes to large axial or lateral expansion joint movements depending on the orientation of the joints.

    Common Design Features:

    Fabric Belt: High temperature fabric belt. (FLEXXCEL HT1, HT3, or HT5 depending on maximum temperature.)

    Accumulation barrier: 6″ minimum standoff and outboard belt attachment flanges to dissipate heat.

    Liner: contoured around expansion joint to allow heat dissipation.

    Recommended Expansion Joint Designs: Style 200W, 100W, 300W, 200B, and 100B

    Fabric Expansion Joint Movement Illustration
    Dirty Flue Gas
    Similar Applications: Cement Plant (Preheat Tower), Refinery (CO Boiler to Precipitator)

    Typical Conditions: 250°F to 500°F operating temperature, -35″ to -50″ WG pressure, flue gas with possibly fly ash carryover through air heater, moderate thermal movements in ducting.

    Common Design Features:

    Fabric Belt: Un-insulated fabric material. (FLEXXCEL HD7)

    Accumulation barrier: Fills expansion joint cavity to minimize the accumulation of particulate.

    Liner: Flow liner to retain the accumulation barrier and protect the belt from abrasion.

    Recommended Expansion Joint Designs:Style 200W, 100W, 300W, 600W, and 700W

    Fabric Expansion Joint Movement Illustration
    Turbulent Flue Gas, Wet Gas
    Similar Applications: Fossil Fired Power Plant (Re-heater to Chimney), Pulp and Paper Plant (Induced Draft Fan to Chimney), Refinery (Steam Generator to Stack)

    Typical Conditions: 250°F to 500°F operating temperature, -35″ to +50″ WG pressure, minimal particulate downstream of precipitator, potential for wet conditions.

    Common Design Features:

    Fabric Belt: At fan locations, the belt material should have a high resistance to flutter. (FLEXXCEL FF1)

    Accumulation barrier: Bolt-in design for attachment to equipment or duct flanges. (If equipment or duct flanges are not present, weld in designs are recommended.)

    Liner: Flow liner to reduce turbulence/flutter of fabric belt material.

    Recommended Expansion Joint Designs: Style 200B, 100B, 300B, 400B, and 500B

    Fabric Expansion Joint Movement Illustration
    Low Temperature Wet Flue Gas
    Similar Applications: Fossil Fired Power Plant (Scrubber Bypass to Stack and Scrubber to Re-heater), Pulp and Paper Plant (Scrubber Inlet and Scrubber to Re-heater)

    Typical Conditions: 120°F to 350°F operating temperature, +5″ to +15″ WG pressure, minimal particulate, highly corrosive wet gas, minimal movements.

    Common Design Features:

    Fabric Belt: Fabric material should have the maximum chemical barrier due to corrosive conditions. (FLEXXCEL HC40)

    Recommended Expansion Joint Designs: Style 100W, 300W, 100B, and 500B

    Fabric Expansion Joint Movement Illustration

    31″ I.D. Custom Turbine Expansion Joint

    August 6th, 2012 Comments off

    31" I.D. Custom Turbine Expansion Joint

    A custom fabricated 31″ I.D. turbine expansion joint was designed and fabricated to be placed in service for a company in Texas. The expansion joint unit was reverse engineered, from the previous unit, with improvements to the current design. It is fabricated from 321 stainless steel with Inconel 625 bellows. The turbine expansion joint is 36″ long and is designed for 70 PSIG at 450 deg. F and axial travel of 4″. The expansion joint was 100% dye-penetrant examined and hydro-tested prior to being shipped to the customer.

    Directional Movement for Fabric Expansion Joints

    July 30th, 2012 Comments off

    Directional Movement for Fabric Expansion Joints

    Fabric Expansion Joint Diagram Showing Axial Compression

    Axial Compression

    The reduction in the breach opening along the axis of the duct. This is usually a result of thermal expansion of the ducting.

    Fabric Expansion Joint Diagram Showing Axial Extension

    Axial Extension

    The increase in the breach opening along the axis of the duct. In certain configurations, the duct thermal expansion may result in extension at the expansion joint location.

    Fabric Expansion Joint Diagram Showing Laterial Movement

    Lateral Movement

    The relative movement of the upstream and downstream faces in the direction perpendicular to the axis of the duct.

    Fabric Expansion Joint Diagram Showing Torsional Rotation

    Torsional Rotation

    The twisting of one side of the duct about the longitudinal axis.

    Fabric Expansion Joint Diagram Showing Angular Rotation

    Angular Rotation

    The twisting of one side of the duct about an axis perpendicular to the longitudinal axis.

    View our online fabric catalog for more information on fabric expansion joint movement
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