Socket and Spigot Flexible Joints are assembled with synthetic EPDM (Ethylene Propylene Diene Monomer) / SBR (Styrene-Butadiene-Rubber) rubber gaskets of special shape - the gasket has a hard ‘Heel’ and a soft ‘Bulb’.
In Push-on joints, the soft bulb of the rubber gasket is compressed when the spigot is inserted into the socket. The 'Heel' locks the position of the gasket and does not allow the gasket to get displaced when the spigot is pushed in. The joint becomes tighter with the increase in internal pressure of water. The rubber is confined in place and cannot blow out.
Where it is necessary to deflect the pipeline from a straight line, either in the vertical or horizontal plane, to avoid obstructions etc., deflection at joint should not exceed the following:
| DN (mm) | Max Deviation Angle |
|---|---|
| 80 - 150 | 5° |
| 200 - 300 | 4° |
| 350 - 600 | 3° |
| 700 - 1200 | 2° |
