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John P. Knezevic

John P. Knezevic
Teaming Partner Manager, Enertech
Phone: +1.714.982.1927


Conval is a premier manufacturer of high temperature, high pressure, and low pressure forged steel gate, globe, check, bellows seal and ball valves. Founded in 1967, Conval is an established supplier of safety-related and “N” stamped valves to the nuclear industry, initially under its 10CFR50 Appendix B program and then, since 2006, its ASME N/NPT program. In 2007, Curtiss-Wright Nuclear and Conval formed an exclusive partnership in an effort to provide enhanced support to the nuclear power industry.


    Bellows Seal

    Traditional packed valves require two different seals to eliminate leakage to the atmosphere; a 360° seal on the valve stem and a 360° seal on the stuffing box. The Conval Bellows Seal removes these two potential leak paths from the valve. The Conval Bellows Seal valves are used when packed valves may not reliably contain light gases and/or hazardous system fluids. The multi-ply Inconel® static bellows stem seal is more reliable than sliding stem seals. Conval Bellows Seal valves also have a secondary graphite packing system and a pressure actuated backseat to contain system fluids in the unlikely event of a bellows rupture.

    Conval has recently introduced a low pressure bellows seal globe valve for those applications, as outlined above, where leakage to the atmosphere cannot be tolerated.

    Key Features and Benefits

    Three Body Styles Available in Y-pattern, Angle-pattern, T-pattern Styles
    Low Operating Torque Provided with a rugged bearing system and grease fitting to minimize operating torque
    Double Back-up Seating In the unlikely event of a bellows failure, leakage to atmosphere is prevented by graphitic packing back-up seal
    Extended Seat Life Solid cobalt-chrome seats and disc provide positive shut-off over a long operational life
    Flexibility of Design Offers double height bellows for applications requiring higher Cv’s
    Long Cycle Life Bellows has been tested to MSS SP-117, and provides the longest cycle life in the industry

    Principles of Operation

    The Conval Bellows Seal can be supplied with a manual operator, an air operator or a motor operator. The valve will open and close when actuated by the operator. The valve plug acts as a sealing element in the valve passageway to stop the flow of the process medium. When the valve plug is tightly sealed against the valve seat, the valve is closed. When the valve plug is away from the valve seat, the valve is open. Valves isolate (shut-off), switch, and control the flow of fluids in a piping system. These valves can be operated manually with levers, wrenches, and gear operators or remotely with electric, pneumatic, electro-pneumatic, and electro-hydraulic powered actuators.

    Manually operated valves (hand valves) are typically used where operation is infrequent and/or a power source is not available. Powered actuators allow valves to be operated automatically by a control system and locally or remotely with push button stations. Valve automation brings significant operation advantages in the areas of process quality, efficiency, safety, and productivity.

    Globe valves have a conical plug which reciprocates into and out of the valve port. Globe valves are ideal for shutoff as well as throttling service in high pressure drop and high temperature applications. Available in globe, angle, and y-pattern designs. Manual operation is accomplished through a multi-turn handwheel assembly. Multi-turn electric actuators are typically required to automate globe valves, however linear stroke pneumatic and electro-hydraulic actuators are also available.

    General Specifications

    Sizes: ½" - 4"
    Ratings: ANSI Class 150#-2500#
    Quality Class: ASME Section III, Class 1, 2 and 3

    Plant Design


    Typical Plant Applications

    • Hot Leg Sample Isolation Valves
    • Pressurizer Liquid Sample Isolation Valves
    • Pressurizer Vent Valves
    • Containment Isolation Test Valves
    • Containment Drain Valves
    • Accumulator Sample, Vent and Drain Valves
    • Reactor Head Vent Drain Isolation Valve
    • Containment Sample and Isolation Valves
    • RCS Pressure Boundary Isolation and Thermal Valves
    • Containment High Point Vent Valves
    • Hot and Cold Leg Root Valves
    • Heat Exchanger Outlet Vents and Drains
    • IRWST Level Isolation Valves
    • Pressurizer Level Root Valves
    • RCP Drain Valves

    High Temperature, High Pressure, and Low Pressure Valves

    Conval's CLAMPSEAL® globe and check valves, Swivldisc gate valves, and CAMSEAL® metal-seated ball valves are all offered under its ASME N-Stamp certification. The CLAMPSEAL® valve line has over 35 years of nuclear experience and is available in three standard body styles in various pressure classes.

    Available Conval Products

    • CLAMPSEAL® Globe Stop/Check Valves
      • Angle
      • T-Pattern
      • Y-Pattern
    • Bellows Seal Valves
    • Throttling Valves
    • Camseal® Ball Valves
    • Swivldisc Gate Valves
    • Whisperjets – High Pressure Drop Applications
    • CLAMPSEAL Strainers
    • Actuator Offerings
      • Electric Motor
      • Pneumatic
      • Piston