Fabric Expansion Joints
DEKOMTE is known for its high quality products in the sector of fabric expansion joints. Not only because of the quality of the materials but principally because of the extensive experience and technical nature that DEKOMTE successfully applied in highly diverse cases. DEKOMTE considers the expansion joint as integral part of the duct compensation system. Only by evaluation and integration of all components; such as duct connection, duct material and the assessment of the supporting steel frame of the expansion joint an optimised solution in regard to technology and price can be found.
Fabric expansion joints are suited for gaseous media, such as air, exhaust gases and solvent fumes, as well as for operation below the dew point (also involving substances with a certain concentration of acids), as well as with abrasive enriched gases (e.g. coal or cement dust). Due to their modular design, fabric expansion joints can especially well adjust to different requirements (e.g. critical sealing requirements, frequent temperature and pressure variations) and therefore cover a very wide spectrum of applications. The high quality materials as well as the technical experience in designing and manufacturing vouch for the high quality and long lifetime of the fabric expansion joints of DEKOMTE.
For example, fire-proof expansion joints – in walls and ceiling passages that meet the requirements of fire safety – can withstand the flames at least 90 minutes (in accordance with DIN 4102). This maximum level of reliability can only be ensured by a high quality production process of the applied materials according to their specific characteristics.
Furthermore, DEKOMTE have the required certificates for radiation resistant materials in the nuclear power sector. The strict safety instructions in the nuclear power sector also apply to expansion joints.
DEKOMTE fabric expansion joints can be used for compensation of axial, angular and lateral expansion movements in pipes. Additional allowable movements are also admissible due to the high flexibility of the fabric and the complex shape of the fabric expansion joints. The large reaction and adjusting forces that are usual for metallic expansion joints can also be neglected in the planning, with minimal duct impact being resulted from fabric solutions. In case of large lateral movements there is the advantage against metallic expansion joints that the compensation performance can be accomplished in a much more compact design. For systems with vibration and oscillation movements special designs are available.
Geometry of fabric expansion joints
DEKOMTE fabric expansion joints are available in any geometric shape (round, square, oval) and in any size. A metal frame, the fabric and if necessary insulation bolsters, together with flow plates and specially shaped convectors form the construction of the fabric expansion joint system. The metal frame serves to fix the fabric and the expansion joint to the duct. The fabric expansion joint takes up movements as well as mechanical and acoustic vibrations. It usually consists of several layers. Each fulfils certain requirements, e.g. tightness, absorption of pressure shocks, insulation and temperature decrease as well as mechanical protection. Depending on the application and temperature additional insulation bolsters are used. Disturbing turbulences are minimised by flow plates and the expansion joint is protected from flow and high velocity. The convectors dissipate the heat to the ambiance to ensure that the maximum operating temperature at the sealing layers will not be exceeded while allowing a minimum temperature drop at the steel parts.
Usually the expansion joint is a multi-layer design. The different layers consist of:
- Temperature and corrosion resistant insulating fabrics for temperature decrease;
- Gas impermeable films, foils or composites of materials as Teflon® (Polytetrafluorethylene, PTFE), Silicone, Hypalon, Inconel or aluminium;
- UV resistant and water resistant materials for reasons of weather protection;
- Support layers such as glass or polyester fabric and the like for pressure absorption;
- Mechanically stable layers such as wire mesh and silicone film as abrasion protection.
Design principle of a high tech fabric expansion joint
1) Convectors for temperature decrease
2) Screw connection
3) Fabric expansion joint
4) Insulation bolster
5) Flow plate design