Metal Seal Gate Valve Manufacturer & Factory

Soft seal gate valves utilize bonded elastomer wedges (typically EPDM or NBR) that compress against smooth cast iron/ductile iron walls. They provide ISO 5208 Rate A (zero-bubble) shutoff, but are limited to clean water and HVAC systems below 120°C and PN16/Class 150 pressures. Metal seal gate valves utilize precision-ground metallic seats (Stellite, stainless steel, or bronze) welded or threaded into cast steel/forged bodies (WCB, WC6, CF8M). They handle severe abrasive slurries, high temperatures up to 550°C, and pressures up to Class 2500 per ASME B16.34 standards, delivering reliable shutoff under conditions that destroy elastomers.

Metal seated gate valves are factory pressure tested per API 598 or ISO 5208 standards. Unlike soft elastomeric seals that demand zero liquid or air bubble leakage (Rate A), metal-to-metal seating permits minor allowable drop counts under specified pressure classes (typically ISO 5208 Rate D or API 598 Table 5 liquid test limits, e.g., drops per minute based on bore size). For critical zero-leakage requirements in high-temperature gas lines, ZFA provides fine-lapped Stellited seats meeting Rate B or Rate C performance.

Thermal binding occurs when a solid wedge is closed while piping is hot; as the line cools, body contraction exerts crushing forces on the wedge, preventing reopening. ZFA implements flexible wedge designs featuring a precision circumferential relief groove cut into the center of the wedge disc. This provides structural elasticity to flex independently against changing seat angles under pipe stress and thermal shock. For extreme cycling services, parallel slide gate valve configurations with spring-loaded disc carriers are engineered.

For standard steam and hydrocarbon service, API 600 Trim 1 (13Cr / F6a) or Trim 8 (13Cr + Hardfaced Stellite) are utilized. For corrosive chemical and acidic environments, full 316 stainless steel (Trim 10) or CF8M casting bodies are provided. In sour gas service containing H2S, all materials strictly comply with NACE MR0175/ISO 15156 guidelines, featuring controlled hardness under 22 HRC, heat treatment verification, and Inconel 625 or Stellite Gr. 6 weld overlays on the seating contacts.

Yes. ZFA offers complete OEM manufacturing capability. We accommodate custom casting patterns, private label yoke badges, specific face-to-face dimensions to match legacy retrofits (including non-standard DIN, BS, or GOST lengths), specialty high-temp epoxy or polyurethane external paint schemes, and electric/pneumatic actuation integration with ISO 5211 direct-mount top flanges.