Product - Ethylene Transfer Line and Docking Valves

​​​​​​​​Double Disc Technology – Double Block and Purge

​We are a world leader in Transfer Line Valves (TLV) & Decoking Valves (DV). IMI Z&J supplies high-quality Double Disc Through Conduit Gate valves which have higher safety levels than any other design. One double disc valve replaces two single gate valves - one plus one as backup installed in the same line to achieve the same safety Ievel.

Within the ethylene process heaters provide the cracking of hydro-carbons by means of hot steam. These heaters (steam crackers) suffer from a phenomenon where deposits of ‘coke’ accrue on the pipework and valves. From time to time these deposits must be removed (‘decoking’), ideally without shutting down the process completely. This is where our valves excel.

​Key features

  • True double block & purge performance within one valve body by means of two independent, separate shut-off discs (independent closure elements). Proven under ​critical/severe service conditions

  • Active, controlled and constant mechanical seating force when closed due to the central split-wedge-ball device

    • safe and reliable tight shut-off

  • Flat or round body valve design

  • Mounting options: flanges or welding ends

  • With reduced or full-bore passage

  • Long-lasting metal-to-metal seats, corrosion and wear resistant

  • Smooth tubular passage ln the open position (valve body free of solid particles)

  • Can be installed in any orientation

  • Designed to customer specifications and German or International standards


  • Positive tight shut-off due to active & controlled mechanical sealing force when shut

  • Excellent performance, no risk of jamming due to internal split-wedge-ball arrangement

  • True Double Block & Purge within one valve body

  • Low wearing due to hardsurfaced seats

  • No build up of coke particles in the body due to guide plates and continuous steam purge

  • Suitable for media with extremely high solid-particle content


  • Accommodates any desired type of actuator
  • Materials selected to suit operating conditions

  • Specially developed technique for crackfree hard-surfacing of the seats of ensures long-term maintenance-free service​

  • No jamming due to forces and moments resulting from the piping system

  • Force release of the discs prior to opening the valve (minimized wear)

  • Central sealing force due to ball-wedge mechanism

  • Seats continuously covered in the end position, thus preventing deposit build-up on the seat surfaces

  • 3 years maintenance free ​

Typical product specification - Double Disc Through Conduit

Up to 525 °C

Up to 1400 mm

ASTM A 515 Grade 60/1.0425 EN (valve body) ASTMA387 Gr.12/1.7335 EN (throughway + discs) 1.4021/ similar to AISITP 420 (stem)

Full bore (reduced bore on request)corrosion and wear-resistant hardfacing on seats, discs and throughway (stellite #6)outside screw-and-yoke type bolted cover valve with goggle plate​

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Product - Ethylene Transfer Line and Docking Valves