Machinery

Ball valve GOST. Classification of ball valves. design features

April 12, 2020

Ball valve, which is issued according to GOST 9702-87, 28343-89, 28908 — 91, 21345-2005 - type of shut-off and control valves with shutter (traffic jam) in the form of a sphere (bullets), through the through round hole in which the working fluid passes. Ball valves, invented more than a century ago, have become popular with the advent of synthetic rubber and fluoroplastic, the use of which ensured the density of the overlap of the circulation of the working medium.

Ball valves are used in almost every domestic and industrial pipeline

Classification of ball valves

According to the diameter of the hole in the shutter (moving element) the inner diameter of the pipe, on which the device is installed, locking devices include:

Full-pass. In a full-bore ball valve, mounted on the pipe, the diameter of the hole in the gate of the ball coincides with the inner diameter of the pipeline. High reliability of full-bore ball valves is manifested in the level of losses of circulating fluid in its open position. It is negligibly small and almost equal to the loss of fluid through the pipe, the length of which is equal to the length of the body of the full-bore ball valve. This level of hydraulic losses is several times lower, than other types of shut-off valves. This circumstance contributed to that, that a full-bore ball valve is in demand as the main shut-off device on the linear part of powerful main pipelines.

Abbreviated or standard. In the abbreviated ball valve, mounted on the pipe, the diameter of the hole in the shutter of the ball is inferior to its inner diameter. The difference is selected in one size. Standard bore (abbreviated) shut-off devices are used in piping systems, for which the partial loss of pressure in the open position of the crane does not become critical.

By type of connection of the device belong to:

  1. Flange. Flange locking devices are installed there, where welding is prohibited. They are also used in pipelines, where the possibility of partial disassembly and further assembly is provided.
  2. Under welding. Ball valves with welded joints are installed, to achieve a special ??strength of the connection and ensure complete tightness of the flow of circulating fluid. This connection is commonly used on hard-to-reach and / or a particularly responsible section of the pipeline.
  3. Couplings. The crane spherical GOST 28908 — 91 equipped with internal conical or cylindrical thread. The main area of ​​their application is utilities.
  4. Combined. Locking devices with combined connection do not have a clear main scope. They are installed in areas of various pipeline systems.

A full bore valve is the most popular type of shut-off valve

Among the special purpose devices are distinguished:

  1. Three-way. With their help redistribute the flows of the working environment.
  2. Equipped with heated housing.
  3. With flow control.

design features

The design of the device consists of:

  • housing;
  • sat down;
  • prison (ball stopper). It is in the device of the locking bodies that the main differences in the performance of the devices are hidden. The design with a floating ball is established on pipes with a diameter to 200 mm. Cork, which is not rigidly connected to the spindle, moves and is pressed by the pressure of the working medium to the seal ring, creating an excessive load on it at large diameters, complicating the operation of the device. The design with a ball in supports is provided with a pin (axial protrusion) at the bottom, included in a special recess, the saddles are pressed under pressure to the surface of the plug. The design is more complex and expensive, but allows much less effort, operating the crane, as manually, and using the drive;
  • handles (for manual control);
  • spindle, transmits force from the handle to the shutter.

The crane body can be plastic or metal, the most durable products are made of steel

The base of the device is made of cast iron, become, bronze or brass. The shutter plug is made of steel (chrome-plated steel) or brass. Saddles - made of Teflon or fluoroplastic. Polypropylene structures have minimal connections. They can be installed, arranging wiring in the apartment, private house. The service life of metal devices is five years, siluminous (disparagingly evaluated by many experts) - up to two years.

Handle colors (levers) indicate the nature of the working environment:

  • red - for hot water, heating systems;
  • blue - for cold water supply;
  • yellow and black - for gas pipelines.

Spherical cranes are brass coupling

Made of wrought brass, are recommended for installation on small diameter pipelines. When a leak occurs, just tighten the nut, pressing the Teflon gland packing. The service life is designed for twenty thousand opening-closing cycles.

The brass device differs in such operational qualities:

  • durability and reliability, no need for oil, technical, maintenance, repair;
  • tightness, which eliminates leakage;
  • possibility of installation in any position;
  • increased traumatic safety of the handle;
  • suitability for operation at operating pressure up to 1,6 MPa and temperature up to +150? WITH.

Couplings are installed on small diameter pipes, mainly, in domestic conditions

Spherical steel cranes

The device consists of an integral spherical body and cylindrical nozzles. Sphere design, made of high quality steel, deprived ??bolted connectors. This eliminates leakage under the pressure of the working medium.

Steel ball valve is characterized:

  • overlapping the flow of working fluid at high speed;
  • easy to install and manage;
  • no need for special maintenance, replacement of parts;
  • resistance to high operating temperature;
  • economy. It is accepted to consider, that these devices are the best choice, based on the notorious value for money, purchased.

What to look for when buying and installing a ball valve

When selecting shut-off valves, it is recommended to make a clear idea of ​​such parameters, related to its further operation:

  • cross sections of pipes in the pipeline system;
  • the possibility of hydraulic shocks, which will affect the ball valve;
  • types and aggressiveness of the working environment, with which you will have to contact the shutter plug (bullets);
  • Like a crane body, which will ensure trouble-free operation.

Cranes of domestic manufacturers are marked according to GOST

Domestic producers (like others, working in the post-Soviet space) mark shut-off valves according to GOST. Products of foreign companies are provided with standard metric designations, the corresponding conditional diameter of the pipe.

Metal products are noticeably heavier than plastic, the difference is easy to determine, just holding the device in your hand. Brilliant shutter device - a sign of quality, the luster is due to the expensive pollination of brass with nickel or chromium.

The ball valve is installed independently by means of such methods:

  1. Flanged. At flange installation flat rings with openings for bolts are imposed on both parties of the crane on bolts.. Tightening of bolts achieves joining and the subsequent fixing.
  2. Threaded. The locking device is installed on the applied thread.
  3. Welded. Shut-off valves are welded to a certain section of the pipeline. The reliability of the connection is unquestionable, but it is difficult to repair or dismantle.

Starting to install the ball valve

The first step in installing a device is choosing a location, where it will be installed. In conditions of limited space, it is important to correctly determine the length of the handle of the locking device, whether it will be possible to turn the long or short handle normally in that place, where it is planned to install the crane. The location of the handle on the vertical pipe does not matter. On the horizontal line, the ball valve handle must be at the top, the permissible deviation from the vertical may not exceed 45 ?.

The method of installation of the ball valve depends on the material of the pipes, from which the pipeline is assembled

The second step is to select a crane with certain parameters. At home, the choice usually stops at the coupling ball valve with threaded connections. A shut-off device with flanges will be required for the diameter of the pipeline, exceeding 40 mm.

The third step is to specify the diameter of the pipes, on which the device will be installed, and types of threads at the ends of the pipes at the installation site.

The fourth step is to specify the direction of fluid flow in the pipeline and the required type of thread on the tap, depending on this factor. This clarification may not be necessary, as most shut-off devices can be installed on either side, regardless of the direction of flow. But some models of ball valves have an arrow - an indication ??the required direction of fluid flow. They can only be installed in a certain way, due to the design features of the structure.

Installation of metal and plastic ball valves

When installing a metal device, the threaded connection is sealed, example, FUM-tape. The valve is not fully screwed when the connection is tight, and yes, to ensure comfortable use of the handle. Upon completion of the installation, you should immediately make sure there are no leaks.

Installing a plastic pipe, all elements should be selected (fittings, pipes, locking device) performed by one manufacturer. Installation requires polyfusion - a special soldering iron for polymer structures in the form of a flat heating element. For soldering of polypropylene products it is necessary to warm up polyfusion to 260? WITH. The tap and pipe are inserted into the nozzles on all sides of the polyfusion and heated simultaneously, not more 6-10 seconds. The softened elements are removed from the nozzles and joined immediately. Cooling completes the soldering process.