Pressure Reducing & Desuperheating Stations


We offer customized solutions with total system end to end station with all necessary mechanical and instrumentation components and take guarantee of entire control system.



• All stations are engineered and factory assembled.
• Most of the PRDS stations are supplied with ‘Combined PRDS’ valves which give the advantage of pressure reduction and temperature control in a single unit.
• If a Combined PRDS unit is not suitable; we offer separate PRV and DSH unit.
• Even with Combined PRDS valve, separate redundant Desuperheater can be included incase of bypass operation when main valve is under maintenance.
• The Water flow control valve and Waterline are also offered with the steam line, which ensures correct design and one to one matching of pressure and temperature control stations.
• It is designed inline with good steam engineering practices using our proprietary software.
• Forbes Marshall manufactures most of the components of pressure reducing and desuperheating stations in-house which, enables quality control as per our standards.
• The entire assembly is hydro tested.
• Various options and makes are available for isolation valve and bypass valves.
• We ensure availability of steam to the process of the right quantity, quality, pressure and temperature.
• For low sizes we maintain same pressure class at the inlet and outlet which allows high robustness and strength for the station. This ensures reliability of station even in case of any malfunction or failure.
• Stations are available in various sizes from 25mm upto 1500mm or more. Pressure class available from ANSI 150# upto 2500# in A106 Gr. B / A335 P11 / A335 P22 materials.


Recommendations for efficient working of PRDS

• Minimum straight length at outlet should be 4 mtrs.
• Minimum distance of Temperature Sensor from the point of water injection should be 10 to 12 mtrs.
• Minimum distance of Pressure Sensor from PRDS Valve should be 1.5mtrs.
• It is recommended to install a strainer of 0.8 mm mesh before water control valve.
• Spray water should be very clean (equivalent to boiler feedwater).
• Instrument quality air is required.


Minimum water pressure  requirement for Combined PRDS:

• Top entry  :  Pw = [(P1+P2)/2 ] + 7 BAR
• Bottom entry through stem :  Pw = P2 + 7
• Bottom entry through nozzle :  Pw = [P1 / 2 ] + 7 BAR

1  Minimum controllable temperature is Saturation Temperature + 7°C.
2 The above are based on a specific set of parameters. These guidelines may change.