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New constructions of control valves

12.03.2013

Below we present new constructions of control valves made ​​by "POLNA" S.A.:

 

 

The valve presented is of anti-cavitation design.
Ceramic elements include plug and seat.
Suitably shaped plug and seat cause a multi-stage pressure drop across a valve in order to limit the danger of cavitation. 
Pressing cage inside the outflow chamber is made of full stellite for protection against erosion of valve body surface.
A body of the presented angle valve is of split design, which enables an easy access to valve internal parts, so as to facilitate checks and servicing.
A valve body of angle or passage design; diameters, pressures, types of flanges shall be adjusted to the Customer’s needs. 

Please watch a short animation presenting the described construction.

 

Minimum flow valve is anti-cavitation valve designed for liquid at the pressure drop up to 200 bar and flow up to 70 t/h. The valve design provides for splitting the pressure drop into six stages to subcritical pressure values causing cavitation. 
High quality of regulation, durability and reliability were achieved, as a result of suitable design of internal elements and material selection. Seat and a three-stage plug are made of ZrO2 ceramics, which is a material of excellent strength and chemical resistance properties. Further pressure drop is achieved through active throttling in three multihole hardened sleeves with radial flow. Valve stem is made of titanium and co-operates with sleeve packing set providing external tightness in accordance with TA Luft regulations.
The valve guarantees high shut-off tightness. It is also possible to adapt this solution for other reliable applications in passage or angle designs.

Please watch a short animation presenting the described construction.

 

All parts of the valve presented were made of 316L steel and counterflanges of X2CrNiMoN22-5-3 1.4462 (DUPLEX).
The valves were made for nominal pressure of PN630 as per BN-91 1771-20/40 standard, due to occurrence of working pressure of 530 bar.
Sealing between valve body and counterflanges was designed based on BX 150 gaskets in accordance with API 6A Class 15000.
The valves feature guaranteed Class V of plug/seat shut-off at the full pressure drop of 530 bar, due to that fluid flow was directed over the plug (FTC).
Pressure difference over and under the plug at shut-off causes additional thrust and unit seal.
In order to reduce required disposable force of actuator, special plug design (plug pressure balanced by inner plug – so called pilot) was applied.  Pilot was selected in such a way that force needed for its opening was 7 times lower than that of main plug. After pilot opening, pressure above and under the main plug equalize and further opening aiming at achieving a full passage does not require higher disposable force of actuator.
In order to prevent a wear and tear of internal parts caused by high velocity of fluid (liquid carbon dioxide) flow, plugs, seats and guiding sleeves were made utilizing full stellited overlay with the hardness of 45 HRC. The valves are equipped with pneumatic actuators, solenoid valves for control and open/closed position indicators.
The valves presented were designed and manufactured for Chemical Fertilizers Institute in Nitrogen Plant in Pulawy.

Please watch a short animation presenting the described construction.

 

2-directional valves are applied in gas engineering in case of a change in fluid flow direction in installation.  Basic design comprises passage cage valve DN300, PN100, Kv1350. Plug design allows for rangeability of 100:1. Plug is pressure balanced by „U” type packing set providing tightness in both directions.
Packing used, as well as plug guiding tape provide for minimum friction factor and excellent tribological properties. Seat hole and outer plug surfaces are stellited, control cage and guiding sleeve are heat treated and gas nitrided, stem is made of titanium. Technology of increasing hardness and materials used guarantee long and reliable service.

Please watch a short animation presenting the described construction.

Animated presentations of new constructions can be found here:

Angle valve with ceramic elements for liquid

Minimum flow valve

Passage flanged valve for 2-directional flows

Passage flangeless valve for working pressure of 530 bar