applications and fabric types fabric expansion joints

Transcription

1 applications and fabric types typical applications Fabric expansion joints compliment the Radcoflex range of metal expansion joints, and provide a viable alternative in applications requiring a light weight joint, relatively low temperatures and zero spring rate. Radcoflex are suitable for a wide range of applications including: * Fans * Baghouses * Coal Feeding * Flue Gas Ducting * Absorbers * Stack and Breaching Seals * Recovery Boilers * Wet and Dry Scrubbers * Precipitators * Power Boilers * Turbine Exhaust * Grate Seals Typical applications include ventilation ducts, flue gas ducts, de dusting ducts, turbine exhausts, breach seals, energy refuse and wet scrubber service, where vibration needs to be absorbed. fabric selections Radcoflex utilises the most sophisticated heat sealable fluoropolymer resin based fabrics available. These fabrics are mechanically rugged, light weight and offer excellent chemical resistance. When selecting a fabric expansion joint it is most important to select a fabric suitable for the application. Radcoflex supply four basic fabric styles all offering high chemical resistance, suitable for dry, moist and wet applications. dry gas service Four products are produced for this application. The lightweight version is DRYSEAL 30 suitable for light duty fans applications or breach seals. DRYSEAL 70 is our normal weight version suitable for baghouses, flue gas ducting and turbine exhausts. DRYSEAL 140 is the heavy duty version ideal for power plants, cement industries and ships. AIRSEAL is a silicone/fibreglass composite with durable coating, and allows bonding (using a room temperature curing silicone adhesive) for expansion joint applications. wet acid service The CHEMSEAL zero porosity fabric is the most advanced material available in the world today. Offering the highest continuous temperature service of 315 C in single ply and incorporating the fluoropolymer coatings. CHEMSEAL has been especially developed to service high temperature and chemical applications where all conventional materials have performed below expectations. Ideal in high acid areas where the dew point is reached each 24 hours such as energy refuse and wet scrubber service. Indeed, CHEMSEAL is virtually a product for all environments. See attached table. reserves the right to change product specifications without notice. Trade Mark of Radcoflex Australia Pty Limited. 2006/07

2 applications and fabric types specifications material temperature deg. C. tensile strength W x F (N/mm) trapezoidal tear strength W x F (kgs) weight kg/m 2 DRY GAS SERVICE DRYSEAL x x DRYSEAL x x DRYSEAL AIRSEAL x WET ACID SERVICE CHEMSEAL CHEMSEAL-C CHEMSEAL-C CHEMSEAL-C CHEMSEAL-C SEVERE CHEMICAL SERVICE ULTRASEAL x x INSULATING FABRIC PJ x reserves the right to change product specifications without notice. Trade Mark of Radcoflex Australia Pty Limited. 2006/07

3 technical considerations expansion joint assembly Radcoflex in general recommends the purchase of complete assemblies, ready for lifting into place. Assembly therefore is part of the price, a fixed cost that eliminates variables which can occur at the site. The fabric element is attached to its flanges at the factory so that its fit and assembly is guaranteed. Large expansion joints, requiring shipment in sections must be factory pre-assembled, matched, marked and packaged for easy assembly after storage. Complete instructions are included with each expansion joint and field service supervisors or installation crews are available if desired. calculating movement In general, the amount of movement a fabric expansion joint is capable of is related to the width of the working face to face (span) of the fabric. fabric expansion joint replacement The fabric portion of an expansion joint should have a long service life that match the life of the ductwork. The eventual replacement of this component should be a consideration in its selection. Radcoflex flat belt style fabric membrane can be replaced at a cost that is only a fraction of the original expansion joint purchase price. Many specially formed fabric elements, which have a slightly lower initial cost, require complete replacement, which results in a significantly higher cost over the life of the plant. field splicing of fabric membranes The flexible membrane of a fabric expansion joint may require splicing at the jobsite, such as for membrane replacement or large assembly installation. Radcoflex can provide heat seal irons, on-site supervision services, and/or detailed splicing instructions if required. The axial movement capability can be calculated by dividing the width of the span by three (3) i.e. a fabric span of 150mm would provide 50mm of axial movement. The lateral movement capability can be calculated by dividing the width of the span by ten (10) i.e. a fabric span of 150mm would provide 15mm of lateral movement. Obviously when joints are required to absorb angular and torsional movements, engineering calculations are required. When in doubt please consult the engineering team at Radcoflex. reserves the right to change product specifications without notice. Trade Mark of Radcoflex Australia Pty Limited. 2006/07

4 components Radcoflex is continually developing materials which maximise corrosion resistance, flexibility and strength. As with our metallic expansion joints, fabric membranes must be strong enough to resist system pressure yet still be flexible. Please find below an outline of the components of our fabric expansion joints using the latest heat sealable fluoropolymer materials. A. gas seal membrane The gas seal membrane is selected to withstand the pressure of the system and be resistant to chemical attack from the interior and the exterior. All our gas seal membranes are flexible so as to absorb thermal movements. As the temperature increases insulating layers are added to protect this membrane from damage. B. insulating layers The insulating layers for CHEMSEAL (C1 to C4) provide thermal protection to the inside layer of the gas seal membrane. This layer also helps to reduce condensation caused by the gas stream contacting the cooler surface of an uninsulated gas seal membrane. C. retaining mesh The retaining mesh is provided to protect the insulating layers from erosion and maintain thermal integrity. This mesh is usually of stainless steel material. D. back up bars Back up bars are positioned above the gas seal membrane so as to apply clamping pressure to the fabric and duct flange whilst also restraining the fabric from moving under the system pressure. Back up bars have radiused edges so as to protect the gas seal membrane from wear damage near the back up bar. E. metal flow liner Liners protect the fabric expansion joint from abrasive particles, and to reduce flutter of the fabric membrane caused by turbulence. A flow liner helps to reduce the temperature impact on the fabric element. F. fly ash seals Our braided stainless steel fly ash seal are intended to deter fly ash building up in the expansion joint cavity. All our fly ash seals are capable of retaining their strength and flexibility while being exposed to maximum system temperatures and pressures. G. flange gasket seal Flange gasket tape is used to seal the gas seal membrane to the mating duct flanges, as well as protecting the gas seal membrane from abrasion. reserves the right to change product specifications without notice. Trade Mark of Radcoflex Australia Pty Limited. 2006/07

5 flyash seals and bolsters An expansion joint typically creates a cavity in the ductwork where flyash or dust can accumulate. When this accumulation becomes severe, it can inhibit movement of the expansion joint. Flyash accumulation can be minimised by carefully calculating liner clearances and adding a flyash seal. Flyash seals are selected depending on the system temperature and media. Two basic configuration are used: 1. The flyash seal, consisting of a thin, flexible material such as fabric, wire mesh or high alloy metal sheet, is used in a variety of environments where a barrier is required around the entire perimeter of the expansion joint. 2. The bolster which fills the entire cavity with a material less dense than flyash, is commonly used on high temperature, dry systems or where flyash accumulation is only a problem on one side, such as the bottom of a horizontal duct. BOLSTER FLYASH SEAL NO SEAL Liners and flyash seals are not leaktight, and serve to minimise the buildup of flyash, rather than prevent it entirely. Minor ash or dust particles may penetrate, but usually not to a damaging degree. The service life of the gas seal membrane and flyash seal depends on the severity of the media, materials of construction, and method of installation. Liners and flyash seals are introduced to help prolong the life of the gas seal membrane element. When the gas seal membrane is ultimately replaced, any accumulated flyash should be removed and a new flyash seal installed. reserves the right to change product specifications without notice. Trade Mark of Radcoflex Australia Pty Limited. 2006/07

6 styles of construction mating duct flanges The style of mating duct flanges will affect expansion joint construction. Radcoflex Frame Styles FWFL and WLW are configured to completely eliminate mating flanges on the ductwork. Other frame styles may be welded to existing flanges, thereby decreasing installation time and corrosion problems associated with bolted configurations. The specifications of duct flanges should be coordinated with Radcoflex. AF ANGLE FLANGE FWFL Best choice when liners (baffles) are required Landing bar type fit permits duct misalignment Accomodates any flat belt selection Shipped fully assembled for easy installation Rectangular joints have full radius corners Low replacement cost of flexible element Best choice for attachment of a flyash barrier Flanges can act as duct stiffeners WLW WELDED Accomodates a flanged duct Bolting accessible from exterior of duct For operation below the allowable service temperature of the gas seal membrane Tack-welded nuts are optional MC MOULDED CORNERS Accomodates any flat belt selection Rectangular joints have full radius corners Shipped fully assembled for easy installation Low cost WLB WLB configuration includes factory bolt holes Tack-welded nuts are optional FFX Dimension X must be specified and includes duct wall thickness Not available for round ducts Accomodates a flanged duct Bolting accessible from exterior of duct Replaces existing moulded corner joints Low initial cost For operation below the allowable service temperature of the gas seal membrane Carriage bolts prevent puncture of fabric element Accomodates a flanged duct Same advantages as a FW configuration * If bolting is necessary, holes matching the duct flange and welded nuts can be provided Radcoflex fabric elements can be replaced without removing liners reserves the right to change product specifications without notice. Trade Mark of Radcoflex Australia Pty Limited. 2006/07