Change Over Valve

  • Change Over Valves (COV) enable a quick and safe switch between product lines, safety systems, or to start-up tanks for solvent  flushing. To accommodate different piping situations COV allows the rotation of the elbows to any 90° angle.
  • Pressurized systems should always be equipped with dual safety relief devices to allow frequent maintenance without disabling the overpressure protection. In many cases safety relief valves are used and are subject to frequent resetting due to operating conditions. COV offer the most convenient and ideal solution considering the short time of operation to switch between the safety relief valve in service and the standby valve. An important safety aspect is addressed due to the fact that the valve does not allow isolating both safety relief devices at the same time. Eliminating two full-bore shutoff valves as well as the reduction from two vessel/ system connections to one provides additional cost benefits.

Application

COV is designed for dual relief valve systems to allow maintenance of the relief valves without the system being down, for reduction of vessel connections, for fast and easy operation, and for protection against involuntary isolation of both safety relief devices at the same time. For applications that require discharge into a collecting system COV provides a simple mechanism for the linkage of two Change Over Valves for simultaneous operation.

These COVs are designed for critical service applications involving lethal, toxic, corrosive, inflammable, volatile, radiating, or expensive fluids.

The new COVs replaces conventional three-way valves that can not provide such reliable and excellent protection against leaks or fugitive emissions. The stem seal requires virtually no maintenance due to leak free weld connections of the bellows with bonnet and stem. Constant valve monitoring and readjustment of the packing is eliminated. In the unlikely event of a bellows failure the backup packing guarantees safe valve performance until the next scheduled shutdown.

For critical services involving toxic, aggressive or corrosive products that pose direct or indirect threads to people, plant, and environment the discharge into a closed collecting system might be required. To achieve this purpose Change Over Valve combinations can be applied to allow the mechanical link of two Change Over Valves. One upstream and one downstream of the safety relief devices. The mechanical link allows operating both valves into the same direction and prevents involuntary isolation of the safety relief devices.

Design features

Bellows and packing

 – multiple walls and hydroformed bellows welded to body and stem for zero leakage.

 – Up to 50.000 bellows operations (cycles) guaranteed.

 – Exposed to flow for self cleaning.

Body and bonnet

  • Split-body design allows for rotation of elbows to any 90° angle to accommodate different installation situation.
  • Body bonnet joint gasket is fully confined to prevent gasket flow or blowout

Seats

  • Solid hard facings for outstanding corrosion and wear resistance
  • knife edge metal-to-metal seat for bubble-tight shutoff
  • replaceable disc for inexpensive maintenance Stem

Stem

  • Two-piece stem protects the bellows against torque stress
  • Design eliminates stem bearings along with their maintenance needs
  • allows easy adaption for any type of actuation

Available Classes: ASME Cl 150 to CL1500

Available sizes: 1/2 to 20 Inch

Temperature Rating: -196°C to 650°C

Body Material:

  • Carbon Steel
    • High and Low Temperature
  • Stainless Steel
    • High Temperature
    • High Chromium
  • Hastelloy
  • Inconel
  • Pure Nickel
  • Titanium
  • other special alloys on request

Connections:
Flanged Ends to ASME B16.5

Butt Welding Ends to ASME B16.25

Socket Welding Ends to ASME B16.11

Threaded Ends to ASME B1.20.1

Operation:

  • Handwheel
  • Chainwheel
  • Gear Operator
  • Pneumatic Piston Actuator
  • Pneumatic Diaphragm Actuator
  • Electric Actuator
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