Pipeline fittings are in demand in almost any system intended for transportation or circulation of liquid and gaseous substances in a closed circuit. Depending on the purpose and design features, such products are presented in various designs.
One of the most commonly used options are control ball valves. Such devices make it possible not only to completely block or open the passage for the working environment, but also to regulate the throughput of the pipeline. This fittings are widely used in various fields of industrial and economic activity. It is used in technological networks of the oil and gas complex, the chemical industry, the heat and power industry, as well as to ensure the operability of hot and cold water disposal and heating systems in public utilities.
Design features
Regulating ball valvesconsist of the following main components:
housing;
ball-shaped shut-off and control element;
drive rod;
sealing seats and washers.
The body of the product can be entirely welded or dismountable. The first option is distinguished by higher reliability, but it is not subject to repair. Collapsible metal structures can be repaired if individual parts fail, which significantly extends their service life.
The main part is a movable ball, which has an oblong through hole that allows the passage of the medium through the pipeline. Its surface is carefully polished, which allows for the tightest fit between the seats, which helps to increase the tightness of the working gaps. Based on the dimensional parameters of the device and its design features, the shut-off ball can be floating or located on special supports.
Based on throughput, devices are divided into reduced (standard bore) and full bore. In the first case, it is assumed that the hole is smaller than the diameter of the connected pipes. The second type of product, accordingly, has a channel cross-section identical to the size of the rolled pipe. An important characteristic is the method of installation in the highway. According to this criterion, structures are divided into the following types:
coupling and fitting - installation is carried out using a threaded connection;
welded - installation is carried out by welding;
flange - there are special disks at the ends that allow installation work using bolted fasteners.
Carbon, low-alloy and stainless steels, as well as high-strength cast iron can be used as materials for the manufacture of the casing. The directly moving mechanism is made from high-alloy alloys that can resist corrosive destruction. Seals, as a rule, are made of wear-resistant polymeric materials, but can also be metal.
Principle of operation
The control valve is controlled by rotating a spherical body through a rod connected to a manual, electromechanical or pneumatic drive. In this case, the working position of the product depends on the degree of rotation of the locking component. If the hole coincides with the direction of flow, then the valve is completely open. To block the movement of the medium, it is necessary to rotate the rod 90 degrees. Adjustment of the power supply of liquid or gas is carried out by partially rotating the part.
