EPDM Limit Tie Restrictive Rubber Expansion Joint PN10 Flange For Sulphide Resistant Line

A restrictive tie joint adds external limit rods to the familiar single sphere body. The rods are anchored on both flanges and set with a defined gap, so the sphere can still absorb vibration and lateral offset but cannot be pulled open beyond the designed travel. This matters on buried mains, on vertical risers and on any line where a pressure surge could otherwise stretch the rubber wall until the arch collapses.

The rubber compound in this version is formulated for sulphide bearing service water and sewage, where ordinary EPDM can harden and crack over time. A protective liner keeps the flange face sealed while the reinforced carcass carries the pressure load. Bolts, nuts and tie rods are galvanised so that the assembly can be assembled outdoors and left in a wet pit without rapid rusting.

• Controlled Axial Travel: Pre-set limit rods allow the designed compression and extension but stop the joint from being pulled apart during surge or water hammer events.
• Sulphide Resistant Compound: The EPDM formulation resists sulphur bearing sewage and process water, which is where standard elastomers age fastest.
• Galvanised Hardware: Tie rods, nuts and bolts are galvanised for outdoor and wet pit installation, keeping the assembly serviceable after years of exposure.
• Lateral Movement Preserved: Even with the rods fitted, the joint still absorbs lateral offset and angular deflection, so misalignment on site is easily taken up.
• PN10 Pressure Class: Rated at PN10 with a 1.5 times hydrostatic test, suitable for gravity mains, transfer lines and low pressure process circuits.
• Simple Spool Replacement: The assembly drops into the space of a standard spool piece, so existing flanges can be reused without cutting back the pipeline.

The tie rod design is used on buried sewage force mains, digester and aeration lines, and on vertical risers feeding clarifiers, where the pipe must not separate under surge. It also suits cooling water headers in chemical plants where trace sulphide is present. Where the line is exposed and accessible, the plain single sphere joint is often sufficient, but for anything buried or subject to pump surge the restrictive tie version is the safer choice.

Joints are assembled, pressure tested and then crated with the rods protected by plastic caps. Inner packing is plastic film and carton, outer packing is a wooden case suited to sea freight. Hardware is bagged and labelled per joint so nothing is mixed on site. Documentation includes the pressure test report, material certificate for the EPDM compound and an installation drawing showing the correct rod gap setting.