Product - VLB Steam Conditioning Valve

​​​​The VLB is an angle-style steam conditioning valve, used for turbine bypass or process control. It is designed to reduce the pressure and temperature of the steam to match the downstream requirements. The valve features a series of pressure reducing stages, designed specifically for each application to minimise noise. Regulation of the pressure is performed with a modulating plug, revealing a series of perforations in the valve bonnet cage as the valve opens. Temperature regulation is controlled by an external spray water control valve. Spray water injection takes place in the valve outlet, using a series of mechanical atomising nozzles.​​


​​Key features​

  • ​Thermally compensated forged body  with uniform thickness
  • Fully customisable inlet and outlet connections
  • Pressure reduction stage and spray  nozzle arrangement optimised for plant operating conditions​
  • Balanced tight design resulting in reduced required opening forces
  • Available with SIL 3 certification
  • Pressure seal bonnet
  • Spring-loaded water injection nozzles
  • Compatible with hydraulic, pneumatic and electric actuators
  • Quick exchangeable seat as option
  • Extended outlet design as option



  • Accurate steam temperature control  and rangeability
  • High perfor​mance and stable control despite plant load transients
  • Quick exchange seat results in reduced maintenance costs and down time
  • Extended outlet design increases  velocity near spray water nozzles and improves evaporation in installations where otherwise the outlet velocity   would be too low
  • Low noise & vibration
  • Leakage class V / MSS SP 61 shut-off class as standard
  • Complies with the following standards: ASME, PED, IBR, CRN, FaMA, MoM, Gost, ISO 9001/14001/18001​

Product specification

Valve sizes
56 - 500 mm seat diameter
Other sizes available on request

Pressure class
Up to ANSI 4500 (higher rating on request)
Above DN400
Design temperature
610 ºC as standard (650 ºC on request)

Leakage class
ANSI Class V / MSS SP 61 as standard​​

Regulatory requirements
ASME, PED, IBR, CRN, FaMA, MoM, Gost, ISO 9001/14001/18001, SIL
SIL classification
SIL 3 achievable for both quick   open and quick close depending on system configuration

Forged material adapted to connecting pipe material

Electrical, hydraulic and pneumatic​​

​​Design features​

Modified linear valve characteristics​
Balanced tight design (BTC)
Allows for greater rangeability and flow control at lower flow rates. The graph shows how at the first ~15% of the stroke, the change in flow coefficient increases  by only 5%.​Provides a leakage tightness according  to ANSI FCI 70-2 / EN 1349 Class V.  The pilot plug lowers the pressure drop across the plug, which reduces the required actuating forces and allows smaller actuators to be used.​​
Quick exchange seat (BTCQL)​
Spring loaded spray nozzles
Suitable for installations where erosion caused by wet steam, or where high velocities can have an adverse effect on seat leakage tightness. The distribution of pressure drops in this configuration reduces the steam velocity across the sealing surfaces.​​Injects spray water into the outlet, perpendicular to the steam flow. The high relative velocity of water to steam creates an efficient secondary atomisation.​​
Pressure seal bonnet
Fully machined circular section
Results in a tight seal at the valve neck while allowing for easy valve disassembly.​​Reduces thermal stress, improves thermal cycling and increases the lifetime of the valve.​​

Applica​tion example​​​​


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Product - VLB Steam Conditioning Valve