EPDM Encapsulated & Vulcanized | Resilient Seated Gate Valves

At Metalsin, we supply ductile iron resilient seated gate valves with non-rising stems (NRS) or outside screw-and-yoke (OS&Y) rising stems for water supply service, covering potable water, wastewater, and reclaimed water applications. These valves feature advanced EPDM rubber seats seamlessly bonded to the ductile iron wedge through a precision encapsulated & vulcanized process, ensuring unmatched durability and zero-leakage sealing. Ductile iron resilient seated gate valves may be designed and manufactured in accordance with EN1171/ EN 1174-2, BS 5163, BS 5150, AWWA C509, AWWA C515, DIN 3352, etc. The sizes available range from 2″ to 48″ in pressure ratings of PN 10 and PN16. They can be operated by handwheel, worm gear, electric actuator, and pneumatic actuator.

Why Choose EPDM?

EPDM encapsulated wedges for ductile iron resilient seated gate valves.

EPDM (Ethylene Propylene Diene Monomer) is a durable synthetic rubber renowned for its exceptional weather resistance, flexibility, and temperature tolerance (-50°C to 150°C), widely used in ductile iron resilient-seated gate valves for water supply applications. Compliant with ASTM D2000, EN 681, ISO 4097, and GB/T 42268, it ensures chemical inertness, low friction, and resistance to water, steam, and mild acids/alkalis (pH 3–11). In water supply systems, EPDM rubber seats provide zero-leakage sealing, adapt to pipe pressure fluctuations, and withstand long-term exposure to chlorinated water without degradation. Its ozone and UV resistance, combined with low torque operation, guarantees extended service life, making it ideal for municipal networks, fire hydrants, and treatment plants where reliability and compliance with global safety standards are critical.

Encapsulating & Vulcanizing Process

Ductile iron EPDM seated gate valves made to BS 5163, DN300 PN15, with non-rising stem, supplied to Brunei.

The vulcanization of the EPDM encapsulated wedge is carried out using a compression molding process. First, the wedge of the gate valve undergoes rigorous surface preparation, including sandblasting and solvent cleaning, to optimize adhesion. A specialized adhesive layer is then applied to the wedge surface before encapsulating the EPDM rubber. The EPDM compound is cut into sheets or strips and applied to the surface of the wedge, which is subsequently put into the compression mold. The cavity of the compression mold reserves the rubber layer thickness (typically 2-5mm) and the seating surface profile. The fully encapsulated wedge is then vulcanized under high temperature (140–180°C) and pressure (10–20MPa). The vulcanized rubber undergoes crosslinking and curing, ensuring that the EPDM layer adheres tightly to the surface of the ductile iron wedge. Post-vulcanization quality checks, including peel tests (≥5MPa bond strength) and hydrostatic tests, guarantee long-term reliability.