ANSI Class 150 Double Flange Triple Offset Metal Hard Sealed Butterfly Valve API 609
The ANSI Class 150 double flange triple offset metal hard sealed butterfly valve is an industrial isolation valve engineered for American-standard pipeline systems where reliable metal-to-metal shut-off, elevated temperature capability and API 609 compliance are required on critical process lines. Manufactured by Trekre Valve at our Wuxi production facility, this double-flanged butterfly valve conforms to ANSI B16.5 Class 150 flange dimensions and incorporates triple-eccentric disc geometry with metal hard seat sealing for dependable performance in steam distribution, hydrocarbon transfer, chemical process branches and general utility headers across North American and export EPC projects.
Compared with resilient-seated wafer designs, the double-flange body provides a stable pipeline connection on both sides, supports higher pipe loads on large nominal sizes and simplifies installation of spectacle blinds, spacers and maintenance spools without disturbing the opposite flange joint. The triple-offset disc path lifts the sealing surface away from the seat during the opening stroke, reducing friction, minimizing wear on high-cycle lines and extending service life under differential pressure when the valve remains closed for extended periods.
Construction and sealing design
Connection type: double flange (flanged ends both sides) per ANSI B16.5 Class 150 raised face; Class 300 and Class 600 pressure stages available when project specifications require higher rating.
Structure: triple eccentric (triple offset) disc geometry with oblique cone seat; one-piece stem with blowout-proof lower bearing and adjustable upper gland packing; disc rotation 90° for full open or closed position.
Sealing form: metal hard seal with Stellite or stainless steel overlay on the disc edge against an integral or replaceable metal seat ring; multi-layer laminated metal seal architecture ensures reliable shut-off on steam, thermal oil and abrasive slurry media where elastomer liners cannot maintain long-term sealing integrity.
Operation: worm gear manual operator as standard on sizes from NPS 6 upward; hand lever on smaller bores; pneumatic double-acting or spring-return actuator and electric multi-turn or quarter-turn actuator available for remote or automated operation on request.
Body material: carbon steel ASTM A216 WCB, low-temperature carbon steel LCB, alloy steel WC6/WC9 for high-temperature service, or austenitic stainless steel CF8 (304) and CF8M (316) castings for corrosive process fluids.
Disc and stem: stainless steel 304/316 disc with optional Stellite hardfacing on the sealing edge; stem in SS416, SS304 or SS316 with surface treatment for wear resistance against metal seats and blowout-proof retention in the body.
Nominal size and pressure rating
Nominal diameter range: NPS 2 (DN50) through NPS 48 (DN1200) depending on pressure class, seat design and actuator torque envelope.
Pressure rating: ANSI Class 150 as primary designation; also available in Class 300 and Class 600 when differential pressure, steam temperature or project piping tables require higher pressure stage. Face-to-face length follows API 609 Category B or MSS SP-68 short-pattern tables and is confirmed against project isometric drawings before shipment.
For saturated and superheated steam service above 200 °C, metal-seated configurations with extended gland packing, heat dissipation fins on the stem seal area and graphite-based packing materials are recommended to protect stem seals from thermal degradation. The Class 150 rating indicates suitability for general process fluids, compressed air, cooling water and steam within the temperature and pressure envelope defined by ANSI valve standards and confirmed by hydrostatic and seat closure testing at the factory.
When selecting between metal hard seal and resilient seat variants on adjacent pipeline sections, consider the minimum operating temperature, required leakage class per API 598 or ISO 5208, and whether the valve will operate in modulating throttling positions where cavitation or velocity erosion may occur at partial openings. Triple-offset geometry is particularly advantageous for metal-seated ANSI applications because the disc lifts off the seat immediately at the start of the stroke, reducing friction and galling on frequently cycled isolation points.
Triple offset geometry and API 609 compliance
Conventional concentric or double-eccentric butterfly valves rely on elastomer liners or PTFE seats that degrade under steam temperatures, oxidizing process gases and abrasive particulates in slurry service. The triple offset path creates a conical closure line where disc and seat contact occurs only in the final degrees of stroke, producing a camming action that wipes the sealing surface clean while avoiding the continuous sliding wear typical of lined discs.
Trekre manufactures this ANSI double flange butterfly valve family in accordance with API 609 Category B design practice for lug and flanged end types, MSS SP-68 face-to-face dimensions and ANSI B16.34 pressure-temperature ratings for body materials. Shell hydrostatic test, seat closure test and operational torque verification are performed before shipment. Material certificates for body castings, seat ring hardfacing records and pressure test reports are available for project turnover packages and third-party inspection on EPC contracts.
The product adopts a three-dimensional eccentric oblique cone valve seat, and the butterfly plate seal uses a precision metal sheet inlay matched to the seat cone angle. When the valve closes, the disc rotates and compresses the seal with increasing contact pressure near the final stroke; when opening, the seal separates completely from the seat, ensuring the sealing surfaces do not slide against each other under full differential pressure. This design reduces operating torque compared with double-eccentric metal-seated valves and supports predictable worm gear and actuator sizing across the full bore range.
Drive methods and actuation
Worm gear manual operation is the conventional drive method for ANSI Class 150 double flange butterfly valves in sizes from NPS 6 upward, reducing handwheel input torque and providing a positive position hold under pipeline differential pressure. The gear unit includes a mechanical position indicator and adjustable stop limits at 0° and 90° disc rotation. For frequently cycled or remotely operated lines, pneumatic actuators deliver fast on/off response and are widely used in petrochemical and power plant utility systems. Electric actuators support 4–20 mA modulating control, open/close limit feedback and bus communication for integration with DCS or PLC platforms.
Actuator sizing must account for valve break torque at maximum differential pressure, safety factor and local ambient temperature limits. The worm gear housing is typically cast iron or aluminum with grease-lubricated worm and wheel gears; gear ratio is selected to keep handwheel rim force within ergonomic limits for the nominated valve size and pressure class. Bare stem ISO 5211 high-platform configurations accept direct-mount electric and pneumatic operators without modifying flange dimensions specified in contract drawings.
Applicable working conditions and industries
This ANSI Class 150 double flange triple offset metal hard sealed butterfly valve is specified for steam headers, condensate return lines, hydrocarbon transfer, chemical process isolation, pulp and paper white liquor systems, district heating branch connections, cooling water circuits and environmental water treatment plants where ANSI-rated flanged valves are the governing connection standard. Metal hard seated versions handle superheated steam, thermal fluids and abrasive slurries at temperatures typically up to 425 °C depending on body and trim materials.
Typical industries include thermal power plants, combined heat and power facilities, refineries and chemical complexes with American OEM equipment packages, LNG and gas processing utility skids, food and beverage steam circuits (stainless steel body variants), and municipal energy stations importing ANSI-rated valve packages. The double-flange format supports stable connection on both pipeline sides, integration with spectacle blinds and maintenance spools, and removal for shop repair when adequate flange gap is provided during piping design.
For mixed-standard projects referencing both ANSI and DIN connections, Trekre can supply companion adapter spools and confirm face-to-face dimensions against MSS SP-68 and API 609 tables to simplify multi-vendor piping coordination on EPC contracts. When bidirectional shutoff is required, request the documented rating and seat-test results for both pressure directions for the exact valve configuration. Triple-offset geometry alone does not establish equal shutoff capability in both directions.
Product parameters
- Valve type: ANSI Class 150 double flange triple offset metal hard sealed butterfly valve
- Model reference: D343H-150 / D373H-150 (project-specific)
- Size range: NPS 2–48 (DN50–DN1200)
- Pressure rating: ANSI Class 150 / 300 / 600
- Body: WCB, LCB, WC6, WC9, CF8, CF8M
- Disc: stainless steel with metal seat or Stellite hardfacing
- Stem: stainless steel 416/304/316, blowout-proof, adjustable packing
- Operation: worm gear / hand lever / pneumatic / electric actuator
- Design standard: API 609, MSS SP-68, ANSI B16.34
- End flange: ANSI B16.5 Class 150 RF
- Test standard: API 598, MSS SP-61, ISO 5208
- Leakage class: metal seat API 598 permissible rate; fire-safe option per API 607
Selection and installation notes
Confirm ANSI Class 150 flange facing (raised face), bolt circle, gasket type and pipeline stress loads before ordering. For steam service, follow the model-specific installation instructions for stem orientation, drainage and actuator protection; do not select a horizontal or downward stem position solely from a general condensate claim. Allow clearance above the worm gear or actuator for maintenance access and handwheel rotation. When mating to non-ANSI flanges, provide adapter spools rather than forcing bolt alignment, which can distort the body and compromise seat sealing.
Trekre Valve application engineers can review your medium analysis, design temperature and cycle frequency to recommend metal seat trim, fire-safe configuration and the appropriate actuator sizing data for your project documentation package. Each ANSI Class 150 double flange triple offset butterfly valve undergoes shell hydrostatic test, seat closure test and operational torque verification before shipment from our Wuxi factory. Material certificates, dimensional inspection reports and torque tables are available for distributor stocking, OEM integration and project procurement.
Frequently Asked Questions
Does Class 150 tell me the allowable pressure at my process temperature?
Provide the design pressure, temperature and selected materials and request the applicable pressure-temperature rating. Do not treat the class name as one fixed working-pressure value.
What must I check to fit this double-flanged valve into an existing spool space?
Compare flange drilling, facing and face-to-face length with the selected drawing. Include disc and gearbox clearance and confirm the exact valve size and connection before approving the replacement.
Does the API 609 reference confirm every test my project requires?
List the design, inspection, testing and documentation requirements and editions in the inquiry. Ask for the applicable scope for the selected valve rather than treating one standard reference as confirmation of every project test.