1.1 Definition of terms
These quality and test specifications apply to fabric expansion joints. Fabric expansion joints are materials which can
be easily deformed in three dimensions by the application of slight pressure.
1.1.1 Applicable Standards and regulations
EN 10204 Metallic products – Types of inspection documents
DIN 53504 Testing of Rubber and Elastomers – Determination of Tensile Strength, Maximum Stress, Elongation at Fracture and Stress Values by a Tensile Test
ISO 7619-1 Rubber, vulcanized or thermoplastic – Determination of indentation hardness – Part 1: Durometer method (Shore hardness)
DIN 53508 Testing of Rubber and Elastomers – Accelerated Ageing
ISO 1817 Elastomere – Determination of the Resistance to Liquids
ISO 132 Rubber, vulcanized or thermoplastic – Determination of flex cracking and crack growth (De Mattia)
EN ISO Textiles – Tensile properties of fabrics –
13934-1 Part 1: Determination of maximum force and elongation at maximum force using the strip method
EN 1593 Non-destructive test – Leak test – Bubble emission techniques Furthermore all Technical Information of the Quality
Association (TI) are available on www.qafej.org.
1.1.2 Structure and function
Fabric expansion joints are single-ply expansion joints or multi-ply expansion joints.
Single-ply expansion joints
consist of elastomers or thermoplasts which are joined firmly together by full-surface welding or vulcanization.
They can be of solid design, in which case they are made only of these materials, or composite designs, in which case they are reinforced with supporting material.
Multi-ply expansion joints
consist of several layers of materials such as:
Thin film, supporting materials. composite materials, coated fabrics and insulation materials.
The various layers are loose in the area of the bellow, but they are joined together in the area where the expansion joint is fixed to its mounting.
The functions of fabric expansion joints are to provide flexible and tight connection of pipe and duct ends as well as other transmissions. They compensate elongations caused by thermal load of the ducting as well as installation tolerances.
Expansion joints reduce the transmission of vibrations and body noise.
Fabric expansion joints consist of thin layers or sheets of thermoplasts or elastomers which are reinforced by metallic, mineral or synthetic materials (see section 2.1.1 and section 3.1.1 for further details).
Fabric expansion joints rnust be designed to absorb such movements as notified to the manufacturer in all spatial dimensions, magnitudes and frequencies, but must not thereby be subjected to any tension by the flanges.
The notified conditions such as temperature, pressure and chemical loading have to be considered.
Supporting materials in composite structures are not permitted to impair the mechanical, chemical or thermal stability of the expansion joint. In multi-ply expansion joints the layers must be arranged so that the maximum permissible temperature of each layer is not exceeded by the given temperature distribution.
1.3 Field of application
The field of application is duct work which convey liquid, gaseous or vapour media, including those carrying or charged with solid particles, such as those found in power Station and plant engineering, e. g.:
– Chemical and petrochemical plant Ventilation plant
– Ventilation systems
– Flue gas treatment plant, such as:
– denitrogenizing plant
– flue gas desulphurizing plant
Single-ply expansion joints are particularly well suited for high chemical loading such as occurs, for example, when the temperature falls below the dew point. They are liquidtight.
Multy-ply expansion joints are particularly applicable to high thermal loads.
If the fluid medium contains solid particles, the expansion joint must be protected against abrasion by metal sleeves.
There are limitations to the suitability of single-ply or multy-ply fabric expansion joints used on flanges subject to strong vibrations (e.g. on vibratory troughs) or subject of continuous cycling from positive to negative pressure.
As a general rule, fabric expansion joints can only be used within the following ranges:
|≤ – 40 mm|
≤ – 60 mm
|≤ + 20 mm|
≤ + 30 mm
|≤ 160 hPa|
≤ 80 hPa
The designation of a single-ply fabric expansion joint must include reference to the elastomeric or thermoplastic material and, if present, the supporting material.
1.5 Details of fixing method
The manufacturer must give details of the fastening method, in accordance with the operating conditions quoted by the customer, e. g.:
– surface quality and condition of the connecting flanges,
– minimum pitch of the bolt hole,
– size and type of bolts,
– specification of the maximum and minimum bolt tightening torque, etc.
1.6 Installation instructions
The manufacturer must issue installation instructions (independently the installation is carried out by the manufacturer, the client or a third party). Aside from describing the different procedural steps, the instructions must also state whether it is necessary to retighten the bolting at its clamping points after initial pressurization under operating conditions.