WCB Body Ball Valve — NPT Thread, Three-Piece, 316 Stainless Steel Internals

The WCB ball valve with NPT thread and 316 stainless steel internals combines the best of two materials in a single component: the WCB carbon steel body provides the mechanical strength and economy of carbon steel for the most demanding pressure conditions, while the SS316 ball and stem ensure corrosion resistance on surfaces directly exposed to the fluid. The result is a valve with greater durability than versions with SS304 internals, at a significantly lower cost than an all-SS316 valve.

The three-piece design allows for complete disassembly of the internals in the field — without removing the valve from the pipeline — for inspection, cleaning, or seat replacement. The integrated ISO 5211 mounting pad guarantees compatibility with any quarter-turn pneumatic or electric actuator on the market.

WCB with SS316 Internals — The Right Combination of Materials

Selecting the correct material for each part of the valve is key to efficient technical specification:

• WCB Body — Mechanical Strength at the Lowest Cost: The valve body does not have direct contact with the fluid during normal operation — it is protected by the PTFE seat and the ball's geometry. WCB provides the necessary mechanical strength for high pressures at a significantly lower cost than SS316. For the fluids handled by this valve (gas, steam, oil, process water), WCB is the correct body material.
• SS316 Ball and Stem — Corrosion Resistance Where It Matters: The ball is the only metallic component in direct contact with the fluid in the open position. SS316, with its molybdenum content, resists corrosion from chlorides, mildly aggressive fluids, and gases with moisture that would attack SS304 or carbon steel in the long term. The SS316 stem resists corrosion from fluid exposure in the packing area.
• SS316 vs. SS304 in Internals: Unlike Cematic flanged WCB valves that have an SS304 ball, this threaded valve has an SS316 ball and stem — greater corrosion resistance to chlorides on surfaces exposed to the fluid. It is the correct specification when the fluid may contain traces of chlorides, moisture with H₂S, or slightly aggressive condensates.

Three-Piece Design — Field Maintenance

The central body houses the ball and seats; the two NPT threaded end caps are screwed on both sides. By unscrewing the caps, the central body becomes fully accessible without removing the valve from the pipeline:

• Replacement of PTFE seats without disassembling the valve from the line
• Visual inspection of the ball to detect scratches or scaling before they cause leaks
• Cleaning of deposits in fluids with solids or paraffins that crystallize on the seat
• The caps remain threaded to the piping during maintenance — without compromising system integrity

Materials of Construction

• Body: Three pieces in WCB carbon steel (ASTM A216 Gr. WCB) — high mechanical strength for gas, steam, oil, and high-pressure process fluids
• Ball: SS316 stainless steel with mirror-polished finish — greater corrosion resistance than SS304 in fluids with chlorides or moisture with H₂S
• Stem: SS316 stainless steel with PTFE packing and anti-blowout design
• Seats: Virgin PTFE — tight shut-off without leaks in both directions. Compatible with virtually all fluids that WCB handles.
• Connection: NPT conical thread (ANSI B1.20.1)
• Lever: Coated carbon steel or stainless steel depending on model
• Actuator Mounting Pad: Integrated ISO 5211

Technical Specifications

• Type: Floating ball, quarter-turn
• Body Design: Three-piece body
• Body Material: WCB (ASTM A216 Gr. WCB)
• Ball: Polished SS316
• Stem: SS316 with anti-blowout design
• Seats: Virgin PTFE
• Stem Packing: PTFE
• Connection: NPT conical thread (ANSI B1.20.1)
• Available Diameters: ½" (DN15), ¾" (DN20), 1" (DN25), 1¼" (DN32), 1½" (DN40), 2" (DN50), 2½" (DN65), 3" (DN80), 4" (DN100)
• Nominal Pressure: Up to PN64 (64 bar) at ambient temperature
• Operating Temperature: -20 °C to +180 °C with PTFE seat
• Port: Full Port
• Actuator Mounting Pad: ISO 5211

Comparison — WCB Threaded Ball Valve vs. Full SS316

Fluid Compatibility

• ✅ Natural gas, LPG, and dry industrial gases
• ✅ Crude oil, process oils, and hydrocarbon condensates
• ✅ Low and medium pressure steam up to 150 °C with PTFE
• ✅ Process water without high chlorides
• ✅ Compressed air and industrial gases
• ✅ Mineral and hydraulic oils
• ✅ Natural gas with traces of H₂S and moisture — SS316 internals resist better than SS304
• ⚠️ Water with chlorides >200 ppm: WCB body may corrode externally — use full SS316
• ⚠️ Concentrated acidic or alkaline fluids: WCB body is not resistant — use SS316 or PFA
• ❌ Seawater, HF, concentrated acids: use SS316 ball valve →

Automation — ISO 5211

The ISO 5211 mounting pad allows direct mounting of pneumatic or electric quarter-turn actuators. For gas and oil services where fail-safe closure of the control system is a safety requirement, specify a normally closed (NC) single-acting pneumatic actuator.

• NC or Double-Acting Pneumatic Actuator: First choice with available air supply. See ball valve sets with pneumatic actuator →
• Electric Actuator: For installations without an air supply or with integrated Modbus. See ball valve sets with electric actuator →

Main Applications

• Oil and Gas: Isolation of crude oil, natural gas, and condensate lines in production facilities, manifolds, and collection stations. The WCB + SS316 combination is the standard specification in Oil & Gas piping classes for threaded valves in hydrocarbon services — WCB handles the pressure, and SS316 internals resist traces of H₂S and moisture in natural gas.
• LPG and Natural Gas — Industrial Distribution: Service points, equipment isolation, and safety valves in LPG and natural gas distribution networks in industrial facilities, hospitals, hotels, and buildings. NPT thread integrates directly into existing installations.
• Steam and Condensate: Isolation of steam traps, equipment bypasses, and service points in steam distribution systems. WCB supports standard steam pressures, and SS316 internals resist the slightly acidic condensate formed by dissolved CO₂.
• Chemical Industry — Fluids Non-Corrosive to the Body: Isolation of service points in process lines where the fluid is not aggressive to the WCB body but may have traces of corrosive agents that justify SS316 in the internals instead of SS304.
• Manufacturing and General Industry: Control of plant services — steam, water, thermal oil, and compressed air — in industrial installations where WCB is the standard material and the robustness of carbon steel is valued over the relative fragility of SS316 to mechanical impact.
• Water Treatment Plants: Service points in process water distribution, instrumentation isolation, and bypass valves in plants where the fluid is process water without high chlorides and WCB is sufficient for the body.

For the complete range of WCB ball valves, see carbon steel ball valves category →

Data Sheet