Wear Resistant Stellite Seat Triple Offset Hard Metal Seal Double Flange Butterfly Valve

The wear resistant Stellite seat triple offset hard metal seal double flange butterfly valve is a quarter-turn shut-off valve designed for abrasive slurry, high-temperature steam and cyclic thermal duty where resilient seated designs cannot maintain seat integrity. Manufactured by Trekre & Fouten Valve at our Wuxi factory, this double-flange butterfly valve uses a triple-eccentric disc path and a welded Stellite STL alloy seat overlay to reduce contact friction during opening and closing while retaining metal-to-metal sealing contact at the closed position.

Compared with conventional concentric rubber-lined butterfly valves, the triple offset geometry lifts the disc off the seat before rotation, limiting scrape wear on the sealing surface. Compared with standard triple-offset designs that rely on layered graphite or PTFE interlayers, this hard metal seal configuration keeps the sealing ring entirely in metal, which suits bidirectional pressure applications and high-temperature lines where non-metallic inserts would degrade. The double-flange body allows direct installation between pipeline flanges with gaskets on both sides, supporting removal for maintenance without disturbing the adjacent spool.

Wear Resistant Stellite Seat Triple Offset Hard Metal Seal Double Flange Butterfly Valve Specifications

Structure and sealing design. The valve body is supplied in a double-flange pattern for inline mounting on water, steam, gas and process headers. The disc follows a triple-eccentric (triple offset) track: shaft offset, disc offset and angular seat cone combine so the disc seals along a conical metal ring rather than by squeezing an elastomer liner. The seat ring is overlay-welded with Stellite STL hard-facing alloy to improve abrasion resistance at the sealing line when the valve operates on fluids carrying fine solids, ash or mineral particles. Bidirectional hard sealing allows installation without regard to preferred flow direction on many pipeline layouts, subject to differential pressure limits confirmed for the ordered size and class.

Nominal size and pressure class. Standard production covers nominal diameters from DN50 to DN1200 (NPS 2 to 48) in common increments. Pressure ratings typically include PN10, PN16, PN25, PN40 and PN63; ANSI Class 150 and Class 300 configurations are available when the purchase specification references API 609 or ASME B16.34 flange classes. Face-to-face dimensions follow EN 558 Series 13/14, API 609 short or long pattern, or project drawings when a non-standard flange drilling is required. Confirm the exact flange standard, drilling table and gasket groove before ordering gaskets and companion flanges.

Body, disc and seat materials. Valve body options include cast carbon steel WCB and WCC for general industrial service, stainless steel CF8 (304) and CF8M (316L) for corrosive or low-carbon weld requirements, and alloy selections for higher temperature headers when specified in the data sheet. The disc is machined from stainless or alloy bar or casting matched to the body material class. The Stellite-faced seat ring is welded and finish-machined to the triple-offset cone angle. Stem and bearing components use stainless steel with anti-blowout retention suitable for horizontal or vertical stem orientation. Packing is selected for the operating temperature band—graphite-based or reinforced PTFE combinations are common on high-temperature steam lines.

Drive methods. Manual worm gear operators with two-stage reduction are standard on larger diameters and higher torque duties. Handwheel or chain-wheel extensions can be supplied for valves installed in pits or with limited headroom. Bare stem with ISO 5211 mounting pad accepts pneumatic or electric actuators when the line requires remote operation or interlock with a distributed control system. Gearbox input stops and position indicators help field verification of open and closed status. Actuator sizing should account for the breakaway torque of metal seated triple-offset discs, which exceeds resilient seated valves of the same nominal size.

Applicable working conditions and industries. This wear resistant hard metal seal double flange butterfly valve is specified on power plant auxiliary steam and condensate headers, metallurgical off-gas and dust handling lines, pulp and paper black liquor circuits, mining tailings and concentrate slurry isolation, chemical process lines with abrasive catalyst fines, and municipal water treatment where long cycle life on metal seats is preferred over frequent elastomer replacement. High-temperature steam and hot gas duties within the seat and body material limits are typical applications where Stellite overlay extends service interval between seat refinishing. Low-leakage performance is verified per agreed shell and seat test protocol; closure leakage is reported per the project test standard rather than a generic marketing claim.

Standards, inspection and delivery. Design and inspection commonly reference API 609 Category B, MSS SP-67, EN 593 or GB/T 12238 depending on the project region. Each valve undergoes shell pressure test and seat closure check before shipment. Material certificates, heat treatment records for Stellite overlay, dimensional reports and operation torque records can be included in the QA dossier when requested. Valves are cleaned, flange-faced protected and packed for export from Wuxi. Trekre & Fouten Valve application staff can review your medium composition, temperature profile, cycle frequency and flange specification to confirm seat hard-facing grade, body material and operator class.

Product parameters

Selection notes. Specify flange standard and pressure class, body and disc material, seat Stellite grade if a project code is assigned, operating temperature and cycle count, and whether the valve must seal with pressure from either direction at the stated differential. For slurry service, confirm solids size and concentration so disc and seat materials are matched to abrasion level. Allow clearance for worm gear height or actuator envelope above the pipeline centerline. Install with the disc slightly open during pipeline flush to protect the seat from debris impact. Trekre & Fouten Valve can supply dimensional outlines and torque data for actuator and support design on your layout drawings.

Maintenance guidance. Periodically exercise the valve through a partial stroke to prevent deposit buildup on the metal seat cone. Inspect stem packing for leakage during thermal cycling; adjust gland bolts within the manufacturer torque band. If closure leakage increases after extended abrasive service, evaluate seat condition—Stellite overlays can often be re-machined or re-welded without replacing the entire body. Do not use metal seated triple-offset valves as tight throttling elements at high pressure drop for prolonged periods unless the sizing study confirms acceptable cavitation and erosion limits for the disc and seat materials.

Comparison with adjacent designs. Resilient seated double-flange butterfly valves remain the economical choice for clean water and HVAC isolation where temperature stays within elastomer limits. Fully welded triple-offset valves suit buried or fully restrained lines that cannot use flanged maintenance access. The Stellite-faced double-flange configuration presented here balances field serviceability—flange removal for shop repair—with the wear resistance needed on steam, slurry and high-cycle metal seat duty. When your specification calls for hard metal sealing without non-metallic seat layers, confirm triple-offset geometry and Stellite overlay grade on the inquiry sheet so the supplied valve matches the intended abrasion and temperature envelope.

This wear resistant Stellite seat triple offset hard metal seal double flange butterfly valve complements resilient seated wafer and lug designs in the Trekre & Fouten product range when temperature, abrasion or bidirectional metal sealing requirements exceed elastomer seat capability. Contact our sales team with flange details, medium data and actuator preference for quotation and delivery schedule from our China valve manufacturing facility.