Flowserve Valtek Valdisk High-Performance Butterfly Control Valve

Overview

The Flowserve Valtek Valdisk is a high-performance butterfly control valve engineered to deliver bubble-tight shutoff, reliable control and accurate throttling in both standard and high-cycle applications. Flowserve developed the Valtek Valdisk to improve uptime and reduce operating and ownership costs in services such as pressure swing adsorption (PSA) and air separation in oil and gas refineries and chemical plants, where a valve may see more than 200 000 cycles per year. The valve is available from NPS 2 to 60 (DN 80 to 600 in the DIN range), in ASME Class 150 to 1500 or PN 10 to 40, with lug, wafer and double-flanged bodies and a temperature range from -196 °C to 427 °C.

Seven Star LLC supplies the Valtek Valdisk and its actuation and instrumentation to refineries, gas processing plants, petrochemical complexes and utilities across the Sultanate of Oman and the GCC, with engineering support in Muscat. We help process and instrument engineers select seat type, body style, pressure class and actuator, and we coordinate the complete valve assembly for projects and replacement needs in Muscat, Sohar, Duqm and Salalah.

Operating Principle of the Valtek Valdisk

The Valtek Valdisk uses a double-offset disc. The shaft is offset both from the centreline of the seat and from the centreline of the pipe, so the disc cams away from the seat as soon as it starts to open and swings back into it only in the last few degrees of closing. This minimises seat and disc wear and leakage, extends seat life and lowers maintenance costs compared with concentric butterfly designs, while the eccentric-cammed disc combined with a high-thrust cylinder actuator enables precise, high-performance throttling.

The soft seat is energised by the pressure drop across the valve itself, so seating capacity rises as differential pressure increases and bubble-tight shutoff is achieved in either flow direction, including alternating flow services. As general engineering background, this pressure-assisted sealing is what allows a butterfly valve to combine the compact face-to-face, light weight and high capacity of a quarter-turn design with the shutoff performance usually associated with globe or ball valves.

Engineering Design of the Valtek Valdisk

Three seat arrangements are offered. The soft seat gives ANSI/FCI 70-2 Class VI shutoff. The metal seat, with a highly flexible lip that maintains full-circle contact with the disc, is used above soft-seat temperature limits and gives Class IV shutoff. The dual fire-safe seat combines the soft seat with a metal back-up that maintains contact if fire damages the soft element, and it also achieves Class VI. Body materials are WCC carbon steel and CF8M stainless steel (1.0619 and 1.4408 in DIN), with other alloys on request, and face-to-face dimensions follow API 609, or EN 558 series 20 for DIN valves.

Mechanically, the Valtek Valdisk uses a one-piece splined shaft end for a tight, lost-motion-free connection to the actuator, tapered pins between shaft and disc that avoid drilling the shaft, anti-blowout shaft retention, a heavy-duty end post and adjustable stroke stops that prevent over-rotation. Packing options include PTFE V-ring, braided PTFE, graphite braid, SureGuard XT and SafeGuard in single, twin, vacuum, live-loaded and fire-safe arrangements. Standard actuation is the Flowserve piston cylinder actuator, using air pressure up to 150 psi (10.3 bar), with the VR spring cylinder rotary actuator and the Limitorque LPS Scotch yoke actuator as alternatives, and the Logix 3800 digital positioner for control.

Key Features of the Valtek Valdisk

The design of the Valtek Valdisk delivers the following benefits:

• Double-offset disc minimises seat and disc wear for long life in high-cycle service.
• Soft seat and dual fire-safe seat give ANSI/FCI 70-2 Class VI shutoff; metal seat gives Class IV.
• Pressure-energised soft seat seals in both flow directions, including alternating flow.
• Sizes NPS 2 to 60 and DN 80 to 600, ASME Class 150 to 1500 and PN 10 to 40.
• Temperature range from -196 °C to 427 °C (-320 °F to 800 °F).
• Fire-safe design to API 607 and ISO 10497, and fugitive emission packing to ISO 15848-1.
• Splined shaft, tapered pins and clamped actuator lever eliminate lost motion for accurate throttling.
• Certifications including ISO 9001, PED, CRN, TRCU and SIL.

Industrial Applications

Flowserve highlights the Valtek Valdisk for demanding high-cycle duties such as PSA units and air separation plants, alongside general control and isolation service in oil and gas, refining and chemical processing. In Oman and the GCC, typical installations include hydrogen PSA units at refineries, nitrogen and oxygen production, gas sweetening and dehydration units, cooling water and seawater control in large utilities and desalination plants, and steam and process gas control in petrochemical plants at Sohar and Duqm.

Seven Star LLC supplies the Valtek Valdisk as a complete control valve package and can match it with other Flowserve control products already in use on site, such as the Valtek Mark One globe control valve for linear control duties and the Logix 3800 digital positioner. For on/off automation of quarter-turn valves, the Rotadisk pneumatic actuator is also available through our team.

Technical Specifications

The Valtek Valdisk specifications below are taken from the Flowserve product brochure:

How to Order

For a formal quotation on the Valtek Valdisk, send Seven Star LLC the process data sheet or the service conditions: fluid, flow range, inlet and outlet pressures, temperature, line size, pressure class, shutoff requirement and actuator air supply. Our engineers in Muscat will coordinate sizing and configuration, confirm delivery and support installation and commissioning in Oman and the GCC. The Flowserve product brochure can be downloaded from this page.