Product - ARS High Pressure Bypass Valve

​​​​​​​​​​​​​HP Bypass Valve​​​​​

The HP-Bypass Valve Type ARS is a steam conditioning valve. It is used for steam throttling with very high pressure drop combined with in-body  desuperheating through spraywater injection. Its prime area of application is high pressure bypass systems for fossil-fired power plants with subcritical as well as supercritical steam conditions. With the range of body materials available, the ARS valve can be applied for main steam pressures and temperatures of todayís most advanced thermal power plants. The valve is specially designed for the cyclic operation of bypass systems. Equipped with a hydraulic actuator and the necessary safety control devices the valve can be used as a combined HP-Bypass and superheater safety valve in accordance with EN4126-5 (TRD 421). The complete system has a type approval for this application.​

Key features​

  • Compact, robust design
  • Bonnet and bolting on low pressure side
  • Optimized body shape for minimal thermal stress
  • Multi-function contoured cage eliminates thermal shocks
  • Few components
  • Easy to maintain
  • Wing type stem
  • Tight shut-off (EN 12266-1 Cl. B or MSSSP61 or ANSI/FCI 70.2 Cl. V)
  • Wide installed base
  • Integral desuperheating; water injection in area of highest turbulence ensures:
    • ​Optimal mixing of steam and water
    • Very short necessary straight pipe length after the valve (approx. 1m)​

  • Integrated desuperheating for shortest evaporation length
  • Designed for frequent start-up
  • Wide installed base
  • Removable stem without dismantling the actuator
  • Available with safety function & type approval according to EN4126-5 (TRD421)
  • Tight shut-off (EN 12266-1 Cl. B or MSSSP61 or ANSI/FCI 70.2 Cl. V)


The valve combines the function of pressure reduction and desuperheating. For pressure reduction a so-called wing type stem is used. This design incorporates specially designed channels that divide the steam flow into discrete paths, resulting in noise level reductions of 10dBA over conventional
plug designs. The spraywater is injected into a zone of high steam velocity and turbulence. This ensures a fine atomization combined with a good mixing of the injected water with the steam, which results in a very short evaporation length and an even temperature distribution at the valve outlet. The specially designed multi-function contoured cage breaks the steam jet into multiple small jets, ensuring noise attenuation. This cage also prevents water droplets from reaching the pressure boundary walls, thereby eliminating any risk of thermal shocks.​

Product specification

​Design code
EN 12516-2, others upon request

Body style
Z-type; Flow-to-open
Spherical shaped valve body

Nozzle connection
For steam pipes: butt-welding according to customerís requirement
For spraywater pipes: flanged connection with butt-welding according to pipe

Steam data range
650∞C / 330bar

Seat/stem tightness
Tight shut-off (EN 12266-1 Cl. B or MSSSP61 or ANSI/FCI 70.2 Cl. V)

Double-acting hydraulic actuator

General information

Replaceable stem/plug without removing the actuator
Replaceable stellited tight seat or hard facing on body
Replaceable multi-function cage
Replaceable spray nozzle body
Bolted bonnet with spray nozzle

Outlet throttling orifice
Transition pieces for large pipe diameters and material compatibility
Prewarming connection

No restriction for the valve operating position
For serviceability and operation, actuator on bottom recommended

Safety valve certificate
EN 4126-5 (TRD 421) ñ Type approval available​

Typical materials

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Product - ARS High Pressure Bypass Valve