Globe Type Control Valve — WCB Body ANSI 150 Flange for Water, Steam, Oil, and Gas

The WCB body globe type control valve with ANSI 150 flange is the proportional control solution of choice in Mexico's heavy process industry: Oil & Gas, power generation, petrochemicals, pulp and paper, and industrial chemicals. The WCB carbon steel body provides the mechanical strength required for the most demanding pressure and temperature conditions, while the SS316 or SS304 stainless steel trim ensures corrosion resistance on the control surfaces in contact with the fluid. Available in sizes from ½" to 8" with corresponding Cv values for each size, it covers everything from small-diameter instrumentation control loops to large-flow main process lines.

The assembly includes a WCB globe body with ANSI 150 flanges, a Normally Closed (NC) pneumatic diaphragm actuator, an electro-pneumatic positioner with a 4–20 mA signal input, and graphite or PTFE packing depending on the fluid and process temperature — all assembled, calibrated, and tested at the Cematic workshop before shipment.

Construction Materials

• Body: WCB carbon steel (ASTM A216 Gr. WCB) — mechanical strength for high-pressure steam services, crude oil, natural gas, condensates, and high-temperature process fluids
• Trim (plug and seat):
  • SS316: First choice — greater resistance to corrosion from chlorides and slightly aggressive fluids. Suitable for process water with dissolved salts, contaminated condensates, oil with traces of H₂S, and wet gases.
  • SS304: For neutral fluids without high chlorides where SS304 is sufficient — demineralized water, clean steam, dry natural gas, compressed air.
• Stem packing:
  • Expanded graphite: For steam, oil, gas, and high-temperature fluids (up to +425 °C). Higher thermal resistance than PTFE — the standard in heavy process services.
  • PTFE: For water, aqueous fluids, and moderate temperature applications (up to +200 °C) where lower operating friction and tighter shutoff are required.
• Connection: ANSI 150 Raised Face (RF) flanges, ASME B16.5 drilling
• Actuator: Pneumatic diaphragm with return spring — linear movement proportional to the positioner signal. Normally Closed (NC) standard.
• Positioner: Electro-pneumatic with 4–20 mA input

Technical Specifications

• Type: Straight-through globe, linear motion
• Connection: ANSI 150 RF flanges — face-to-face according to ASME B16.10 Series 1
• Body material: WCB (ASTM A216)
• Trim: SS316 or SS304 as per specification
• Stem packing: Graphite or PTFE depending on fluid and temperature
• Nominal diameters: ½" to 8" (DN15 to DN200)
• Nominal pressure: ANSI 150 — up to 19.6 bar at ambient temperature; reduced at higher temperatures according to ASME B16.34 table
• Operating temperature: Up to +425 °C with graphite packing
• Flow characteristic: Equal percentage standard
• Positioner input signal: 4–20 mA
• Actuator action: Normally Closed (NC) — fail-close. Air opens, spring closes.
• Air supply pressure: 1.4–6 bar
• Design standard: IEC 60534 / ASME B16.34

Flow Coefficient Cv by Diameter

Cv is the flow rate in gallons per minute (GPM) of 60 °F water that passes through the valve with a 1 psi pressure drop in the fully open position. To ensure control stability throughout the range, the normal operating Cv should be between 20% and 80% of the maximum Cv of the selected valve.

Not sure about the correct diameter for your process? Use our Cv Calculator → or share the fluid, flow rate, and pressures with our technical team for free sizing.

Fluid Compatibility — WCB with SS316 Trim

• ✅ Saturated and superheated steam up to 425 °C
• ✅ Hot water and boiler water up to 425 °C
• ✅ Natural gas, LPG, and dry industrial gases
• ✅ Crude oil, process oils, and hydrocarbon condensates
• ✅ Industrial process water with moderate dissolved salts
• ✅ Diluted acids of low concentration (with SS316 trim)
• ✅ Process fluids in refining and petrochemical industry
• ⚠️ Water with chlorides >1,000 ppm at elevated temperature: check with technical team
• ⚠️ H₂S in high concentration: specify NACE MR0175 materials resistant to SSC
• ❌ Concentrated acids (HCl, H₂SO₄ >30%), HF: use SS316 body or special materials

Fail-Safe — Standard NC for Heavy Process

The Normally Closed (NC) configuration is the safety standard in the Oil & Gas, refining, and heavy process industry: in the event of any loss of compressed air supply or controller signal, the actuator spring closes the valve, interrupting flow. This is the correct safe position for:

• Steam control valves — fail-to-close prevents over-temperatures in process equipment
• Feed valves to reactors and distillation columns — fail-to-close stops feed until control is restored
• Valves in oil and gas lines — fail-to-close contains the fluid in the line

Normally Open (NO) configuration available upon request for services where continuous flow is the safe state (cooling water, lubrication of rotating equipment).

Cematic Control Valve Family Comparison

Main Industries and Applications

• Oil & Gas — production control: Flow regulation of crude oil, natural gas, and formation water in production facilities. Pressure control loops in gas-oil-water separators. The WCB + SS316 trim + graphite combination covers typical production fluids at standard process temperatures and pressures.
• Refining and petrochemical: Control of process steam, boiler water, and process fluids in distillation, reforming, and catalytic cracking units. Diameters from 3" to 8" cover the main steam distribution lines in these facilities.
• Power generation: Control of turbine inlet steam, boiler water regulation, and process fluid control in combined cycle and cogeneration plants. Graphite packing withstands superheated steam up to 425 °C without degradation.
• Pulp and paper: Steam control in digesters and evaporators, black and white liquor regulation in the Kraft process, bleaching fluid control. The SS316 trim resists alkaline papermaking fluids better than SS304.
• Chemical industry: Temperature, pressure, and flow control loops in continuous reactors and distillation columns where WCB with SS316 trim provides the required chemical compatibility.
• Industrial HVAC and buildings: Control of steam and hot water in heating systems for large industrial and hospital facilities. Diameters from 2" to 6" cover the main steam distribution lines in these systems.

For the complete category of control valves, see Cematic Control Valves →

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