Application

Extraction Check Valves for steam - ANSI are valves used to prevent the back flow of the service fluid in extraction lines of steam turbines. Each extraction check valve is designed exactly for the specified extraction parameters.

Working medium

steam, gases. If with actuator - no more than 80 C temperature;

Working temperature

• +450°C to DN 800, NPS 32“
  
• +350°C to DN 800, NPS 32“
  

Technical description

The extraction check valve is designed as a swing check valve with double eccentricity. The disc with conical sealing surface is swinging on a shaft which is carried in plain bearings. In the „CLOSED“ position, the sealing surface of the disc is in contact with the valve body seat. The way of swinging is pressure equalized, there are no axial forces acting on the shaft. The shaft bears also a counterweight to balance the mass of the disc. The balancing guarantees minimum pressure losses not exceeding 1%. This counterweight is situated outside the valve, off the valve body bore, in a separated pressureclosed

box. The extraction check valve is equipped with an actuator which guarantees the quick-acting function of the valve and a lever to test the valve function as a standard. Both the actuator and the lever are carried on a separate shaft so that their passive resistances to not affect the valve function. The welded design of the extraction check valves meets the requirements of EN ISO 15614-1, PED 97/23/ EC or, if required by the customer, ASME CODE, Section IX.

Operation

Self-acting, the safe closing of the disc is realized by the ancillary actuator (pneumatic, hydraulic actuator). Actuator type as specified by the customer.

Connection to the piping

• flanged ends according to ASME B16.5, ASME B16.47,
  
• face-to-face dimensions according to EN 558, series 14,15
  
• welding ends according to EN 12627, ASME B16.25, end-to-end dimensions according to EN 12982
  

Testing

The valves are tested in accordance with:

• EN 12266-1 / ISO 5208
  
• API 598
  
• ASME B16.34
  

TDS