The role of plant management is to operate both efficiently and safely. Just as blood is pumped around our body through a network of arteries and veins, the lifeblood of most industrial processes is usually pumped through a vast network of pipes and valves.

With pumps providing the required head and flow, valves are then used to relieve pressure (safety valves), mix and direct flow (control valves), and isolate one section of pipework from another (isolation valves of various designs, for example ball, gate and butterfly valves).

Where absolute isolation is necessary for either process or safety considerations then the selection of the correct valve becomes critical.

For almost 50 years the triple offset valve has been continuously developed to fill this space. Known as triple offset because the axis controlling rotation and seating are displaced from their traditional position, these valves offer some unique benefits to many industry applications.

The greatest of these advantages is the low torque required for sealing and the high integrity level of the seal.

Unlike a traditional butterfly valve which relies on greater force to achieve better sealing, the triple offset design allows the disc to move to its final sealing position with extremely low torque, then the high-level sealing is achieved by way of a laminated disc face closing onto a stellited seat.

The ARI ZETRIX triple offset valve guarantees a permanent, tight seal conforming to leakage rate A according to DIN EN 12266-1. In addition, the ZETRIX valve has been tested and approved as fire safe, according to German clean air regulations (TA-Luft), SIL and ATEX. The wide operating temperature range of -60 °C to +427°C allows the ZETRIX valve to operate in most liquid, gas and steam applications.

In the UK, the ZETRIX valve is increasingly being installed in a double block and bleed arrangement to meet the stringent demands of British HSE Guidance 253. In many piping installations the overall length of this configuration is actually shorter than the existing isolation valve and thus can easily be installed with minimal piping modifications.

With end connections available in butt weld, fully lugged and double flanged—and overall design in conformance with most international standards (EN 12516, ASME B16.34, API 609)—the ZETRIX triple offset valve is the natural choice for many traditional (and harsh) industrial applications.

Where an emergency shutdown function is demanded, ARI engineers have the expertise to design the required actuator mechanism. For one such recent application ARI achieved a 0.6 second close time on a DN600 (24”) ZETRIX valve. This performance provides reassurance of complete safety, with a quality valve designed to rapidly stop the flow of a hazardous fluid or gas upon the detection of a potentially dangerous event.

With the available size range being constantly increased—currently double flanged DN80 to DN1200, lugged DN80 to DN600, and butt weld ends DN80 to DN600—the ARI ZETRIX triple offset valves, in cast and stainless steel, are being installed for liquid, gases and steam applications in:

  • Oil and gas processing
  • Refineries
  • Petrochemical plants
  • Solar thermal power stations
  • Power plants
  • District heating (Europe)
  • Pulp and paper production
  • Steelworks
  • Sugar processing
  • Industrial and plant manufacturing in general

This partner content was brought to you by Pressure and Safety Systems. for more information, contact

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