2-pc Cast Steel Floating Metal Seated Ball Valve

A 2 PC cast steel floating metal seated ball valve seals ball-to-metal-seat instead of relying on a polymer insert, so it serves high-temperature, abrasive, slurry and fire-risk lines that exceed the practical limits of soft-seated valves. The ball and seat faces are hard-faced (Stellite, tungsten carbide or nickel alloy) and precision-lapped, with a spring-energized seat that holds contact through thermal movement. Leakage is verified to ISO 5208 Rate D; the design is inherently fire-safe per API 607. Send your service data for a confirmed quote.

Metal-to-Metal Sealing Principle

In a metal-seated valve the ball and the seat ring are both finished with a hard facing and then precision-lapped to a line contact, so the seal comes from matched metal surfaces rather than elastomer deformation. A spring (typically a Belleville disc spring) pre-loads the seat against the ball, keeping contact at low pressure and compensating for the different thermal expansion of the ball and body as temperature rises. Under line pressure the floating ball shifts and loads the downstream seat, energizing the seal. Because metal-to-metal contact cannot deform to close every path, the accepted leakage is ISO 5208 Rate D - an allowable rate, not bubble-tight shutoff. The ball and seat are paired with dissimilar hard materials to avoid galling (cold welding) during rotation.

Rate D is the correct leakage reference for metal seats. A tighter result may be achieved on well-lapped trim and reported as "Rate D or better" per EN 12266-1; the accepted rate is defined by the purchase order.

Design Standards

Design Features

1. Double sealing system of packing, and firesafe design
2. Wear-resistant and scour resistant sealing design
3. Integral anti-blowout design structure of the stem
4. Optional locking device
5. Independent limit structure design
6. Low torque design
7. Solid ball design
8. Ball and seat surface are coated with super wear-resistant alloy to ensure service life and sealing reliability.
9. Fugitive emission test meets API 624, ISO 15848 and other specifications.

General Assembly Drawing

Material of Construction

Note:

Floating metal seated ball valve can be designed as asymmetric structure according to customer requirements, with the same seat material and sealing surface on both sides.

Materials listed in the table are general. When ordering, please contact SNY sales or technical team to confirm the details.

Dimension & Weight

CLASS 150

CLASS 300

CLASS 600

CLASS 900/1500

Hard-Facing and Seat Coatings

The wear and temperature performance of a metal-seated valve comes from the hard facing on the ball and seat. Coatings are applied by HVOF (high-velocity oxygen fuel) thermal spray or weld overlay, reaching 56–75 HRC. The choice matches the failure mechanism: cobalt-chromium alloys for high temperature and oxidation, tungsten carbide for erosion and slurry, and nickel alloys for chemical resistance.

Ball and seat are paired with dissimilar materials (for example a tungsten-carbide ball against a Stellite or chrome-carbide seat) to prevent galling. The exact pairing is selected by temperature, medium and abrasiveness.

Leakage Class and Fire-Safe Performance

Metal-seated valves are accepted at ISO 5208 Rate D when tested per API 598, ISO 5208 or EN 12266-1 - an allowable metal-to-metal leakage, not zero leakage. Because there is no polymer seat to burn away, the valve maintains isolation through fire exposure and is inherently fire-safe; fire-safe performance is verified to API 607 or ISO 10497, with graphite stem packing and a graphite body gasket. Anti-static continuity between ball, stem and body is provided per API 608, and fugitive-emission stem sealing to ISO 15848 is available where the project requires it.

Temperature and Abrasive-Service Capability

Typical metal-seated service reaches well beyond the ~200 °C soft-seat limit. An indicative range is about −29 °C to +538 °C for a cast steel body with hard-faced trim; the actual upper temperature is governed by the seat hard-facing, coating and body material per ASME B16.34, so it must be confirmed against the ordered configuration. Many designs use a self-cleaning scraper seat that wipes the ball during rotation, letting the valve shear through fibres, small solids and crystallizing media that would destroy a soft seat.

Temperature and abrasion limits are indicative and depend on hard facing, coating, body material and medium. Confirm the operating envelope against the data sheet and purchase order.

Applications

Superheated steam and hot-gas lines in power and refinery service.

Thermal oil and heat-transfer fluid systems above soft-seal limits.

Slurry, tailings, mining and mineral-processing lines with abrasive solids.

Coking, coke-drum and catalyst-handling lines where erosion is the failure mode.

Fire-risk hydrocarbon isolation requiring inherent fire-safe performance.

Chemical lines with crystallizing or fibrous media that foul a soft seat.

Suitability depends on medium, temperature, pressure, abrasiveness and project specification. The metal-seated valve is chosen where a soft-seated valve cannot meet the temperature, wear or fire requirement; it is not a substitute where bubble-tight (ISO 5208 Rate A) shutoff is mandatory.

Procurement and Documentation

Standard delivery documents include the material and hard-facing certificate, pressure-test record and marking per MSS SP-25; EN 10204 3.2 with third-party attestation, extra NDE and low-temperature or sour-service verification are added where the purchase order requires them. Each valve carries a heat or serial number for traceability. Export packing, end protection and transport documents are arranged to the destination and schedule agreed in the order.

FAQ

What is a metal-seated ball valve and when is it needed?

A metal-seated ball valve seals ball-to-metal-seat instead of using a polymer insert. It is specified where the service exceeds the practical limits of a soft-seated valve: high temperature above about 200 °C, abrasive or slurry media, fire-risk hydrocarbon lines, or where a long, low-maintenance life in severe duty is required. The ball and seat faces are hard-faced and precision-lapped.

What leakage class applies to a metal-seated ball valve?

Metal-seated valves are verified to ISO 5208 Rate D - an allowable metal-to-metal leakage, not bubble-tight shutoff. Depending on lapping and trim, a tighter result may be achieved and reported as Rate D or better per EN 12266-1. This is the correct leakage reference for metal seats; confirm the accepted rate against the purchase order.

How hot can a metal-seated floating ball valve operate?

Typical metal-seated service reaches well beyond the ~200 °C soft-seat limit; an indicative range is about −29 °C to +538 °C for a cast steel body with hard-faced trim. The actual upper temperature is governed by the seat hard-facing, coating and body material per ASME B16.34, so confirm the operating envelope against the ordered configuration rather than applying a single fixed value.

What hard-facing materials are used on the ball and seat?

Common hard facings are Stellite 6 or 21 (cobalt-chromium), tungsten carbide (WC-Co), chrome carbide (Cr₃C₂-NiCr), nickel alloy (Ni60) and hard chrome, applied by HVOF thermal spray or weld overlay to 56–75 HRC. The ball and seat are paired with dissimilar materials to avoid galling during rotation.

Is a metal-seated ball valve fire-safe?

Yes. Because there is no polymer seat to burn away, a metal-seated valve maintains isolation through fire exposure and is inherently fire-safe. Fire-safe performance is verified to API 607 or ISO 10497, with graphite stem packing and a graphite body gasket; anti-static continuity per API 608 is provided.

Can a metal-seated valve handle slurry or abrasive media?

Yes. Hard-faced seats resist wear from slurries, catalyst particles, sand-laden streams and fibres. Many designs use a self-cleaning scraper seat that wipes the ball during rotation, and a spring-energized seat keeps contact as parts wear. Select the hard facing by the wear mechanism and medium.

Which standards apply to 2-piece cast steel metal-seated floating ball valves?

Design is to API 608, with pressure-temperature limits taken from ASME B16.34 and international references under ISO 17292; pipeline service may follow API 6D. Face-to-face follows ASME B16.10 and testing follows API 598, ISO 5208 or EN 12266-1, with seat leakage to ISO 5208 Rate D. The applicable edition of each standard is defined by the purchase order.

What details are needed to request a quotation?

Provide the nominal size and pressure class, body material, hard-facing and seat material, bore type, end connection, operating temperature and medium (including any solids or abrasives), fire-safe or anti-static requirements, inspection and documentation level, quantity, destination and schedule, plus any drawing or data sheet.

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