There are three main types of control valves; globe, ball, butterfly and axial flow. Globe and butterfly valves are the most widely used.
Different trim sets are designed to work within defined operating parameters. Incorrect use can cause trim damage.
Control valves have tightness classes which varies from I to VI according ANSI FCI 70-2. They varies from having relatively large leakage rates to be approximated tight.
AST produces a complete series of control valves with electric or pneumatic spring-diaphragm actuators.
Materials: carbon steel, alloy steel, hastelloy, monel and other materials upon request.
Accessories: handwheels (side and top mounted), stem bellows for bubble tight sealing, pneumatic, electropneumatic or digital positioners, filters, boosters, lockup valve etc.
Balanced plug available in the whole range of temperatures and ratings.
Internal thermal differential compensation system allowing to extend working temperature up to 566 °C.
Wide range of trim configurations: cage conventional, low noise, multi-step anti-cavitation, velocity control multi-path, multi-stage for severe service applications.
Tightness up to class VI under 200 °C and up to class V in the whole range of temperature (up to 566 °C)
Quick change trim with seat locked by bonnet trough cage
Thanks to the availability of a complete range of steam desuperheaters, AST can supply the optimal solution for whichever steam conditioning application.
An experienced technical staff is available to support the customer in selecting the most appropriate solution and providing support for a correct piping layout, allowing an optimal installation and satisfactory operation of the equipment supplied.
Specifically designed for severe steam conditioning services such as steam turbine bypass stations and all applications where perfect seal, frequent start-up from cold or warm conditions and fast opening is required.
This valve series is designed and manufactured to resist to aggressive and corrosive fluids, as per Urea plant application. Although these valves have been designed for high pressures, they are also available for low pressure with special materials.
The valve body is generally from casting for pressures class 150 to 600, whereas for high pressure class and Urea application it is supplied in forged block only. Valve body can be jacketed type and heated by steam or diathermic fluids.
The peculiarity of these valves is that they are made from a forged block body, in a single piece including bonnet. The total absence of threads in all the parts in contact with processing fluid, the absence of stagnation areas and the stem stiffness complete their features.
The expertise gained in the field of urea and melamine plants, the optimization of fluid-dynamic features and the use of specific materials allow to obtain a high resistance to erosion and corrosion, at high pressure, at high operating ΔP, and at high temperature.
The peculiarity of these valves is that they are made from two special material forged blocks angle welded with qualified welding process, to realize a single piece body including bonnet. The total absence of threads in all the parts in contact with processing fluid, the absence of stagnation areas and the stem stiffness complete their features.
The valve body and connection flanges are fully jacketed for heating by diathermic fluids to avoid any fluid crystallization.
The expertise gained in the field of melamine plants, the optimization of fluid-dynamic features and the use of specific materials allow to obtain a high resistance to erosion and corrosion, at high pressure, at high operating ΔP, and at high temperature.