1. Procedures
a. Cracking. (Sun Checking) Cracking, or crazing may not be serious if only the outer cover is involved and the fabric is not exposed. If necessary, repair on site with rubber cement where cracks are minor. Cracking where the fabric is exposed and torn, indicates the expansion joint should be replaced. Such cracking is usually the result of excess extension, angular or lateral movements. Such cracking is identified by: (1) a flattening of the arch (2) cracks at the base of the arch, and/or (3) cracks at the base of the flange. To avoid future problems, replacement expansion joints should be ordered with control rod units.
b. Blisters-Deformation-Ply Separation. Some blisters or deformations, when on the external portions of an expansion joint, may not affect the proper performance of the expansion joint. These blisters or deformations are cosmetic in nature and do not require repair. If major blisters, deformations and/or ply separations exist in the tube, the expansion joint should be replaced as soon as possible. Ply separation at the flange O.D. can sometimes be observed and is not a cause for replacement of the expansion joint.
c. Metal Reinforcement. If the metal reinforcement of an expansion joint is visible through the cover, the expansion joint should be replaced as soon as possible.
d. Dimensions. Any inspections should verify that the installation is correct; that there is no excessive misalignment between the flanges; and, that the installed face-to-face dimension is correct. Check for over-elongation, over-compression, lateral or angular misalignment. If incorrect installation has caused the expansion joint to fall, adjust the piping and order a new expansion joint to fit the existing installation.
e. Rubber Deterioration. If the joint feels soft or gummy, plan to replace the expansion joint as soon as possible.
f. Leakage. If leaking or weeping is occurring from any surface of the expansion joint, except where flanges meet, replace the joint immediately. If leakage occurs between the mating flange and expansion joint, tighten all bolts. If this is not successful, turn off the system pressure, loosen all flange bolts and then retighten bolts in stages by alternating around the flange. Make sure there are washers under the bolt heads, particularly at the split in the retaining rings. Remove the expansion joint and inspect both rubber flanges and pipe mating faces for damage and surface condition. Repair or replace as required. Also, make sure the expansion joint is not over elongated, as this can tend to pull the joint flange away from the mating flange resulting in leakage. If leakage persists, consult the manufacturer for additional recommendations.
The Installation/Inspection Instructions are considered to be the best industry practices and are defined by the Fluid Sealing Association Technical handbook 7th Edition Non-Metallic Expansion Joints and Flexible Pipe Connectors.
2. Product Features:
(1) Economy: Compared with the systems of mechanic stretching and material damping, it has the advantages of little space covering, light weight, easy assembly and disassembly, labor saving and low cost. Its smooth inner wall can reduce flow resistance. It has good water tightness, so there is no need of gasket during the installation. It has wide application, large temperature-resistance scope and long working life. (This product can be used for 20 years if it is used indoors.)
(2) Displacement: Flange is free from pipe decentraction and imbalance. Its good flexibility allows compression, extension, distortion, deflection of vertical displacement, etc. which can prevent the pipeline from damage of deformation and foundation settlement arising from expansion caused by heat and contraction caused by cold.
(3) Shock and noise absorption: The large damping of rubber sphere can effectively buffer and isolate vibration, control and reduce mechanical vibration, and absorb fluid impact noise. The reasonable installation between vibrating machine and metal pipe can decrease structure-borne noise by 15-25 decibels.
(4) Pressure resistance: The multilayered sphere structure can especially endure internal pressure, withstand strong blasting force and impact, and prevent deformation from external pressure. There are many pressure standards on work piece.
(5) Reducibility: After external force compressed, it can recover to original state when this force is removed.
(6) Wide application: Different rubber material and formula can make product possess different resistance to heat, oil, corrosion, age, abrasion and ozone.
3. Classification
(1) According to appearance:Concentric with diameter rubber joint, concentric reducer rubber joint, eccentric reducer rubber joint.
(2) According to the structure:single ball flexible rubber joint,Double sphere rubber joint,spheres rubber joint, elbow sphere rubber joint.
(3) According to link the form:flange coupling,Threaded joint
(4) According to working Pressure:0.25MPa,0.6MPa,1.0MPa,1.6MPa,2.5MPa,6.4MPa