The shut-off valve actually serves to block the flow of the working medium of the pipeline. However, technical characteristics of this device also allow to regulate the volume of the transported substance, as well as the speed of its movement. The flange valve is widely used in heating, water and gas systems. Due to its convenient and reliable design, this part is in high demand in the construction market.
Flange valves are installed as shut-off valves for pipelines for various purposes
Classification of devices
According to the method of overlapping the flow of the working medium, there are four types of valves.
Screw. The movable valve is fixed to the rod with a threaded connection. It presses against the seat located in the valve body. Tightness provides stuffing box stuffing, which is a sealing washer. This valve has the following specific disadvantages:
- able to pass the liquid in only one direction;
- wear of paronite or rubber gaskets requires periodic replacement. And got under the valve scale or sand can cause their partial or complete destruction.
Sunroof. In structure, they are more like a latch, than the valve: the conical valve is lowered between the two mirrors by means of a threaded rod. Durable polymer or rubber seals are often used instead of a stuffing box.
Ball valve is the most modern design of such devices
Bullets. Made of stainless steel or brass ball, has a through hole, rotating in the valve body when turning the handle. It is fixed by a pair of fluoroplastic or Teflon ring seats. Sealing of a rod is provided by a lining from the same material.
Cork. The flow in them is blocked by a conical plug with a through hole. Typical problems are as follows:
- periodic stuffing of an epiploon is required;
- turning the plug in a large valve requires considerable effort.
Varieties and features
Consider the features of flanged valves depending on the material of manufacture. For industry, it is often steel and cast iron, and for household needs - brass or bronze.
The valve is steel. This part is installed on pipelines, mainly, for water and steam. in addition, as the working medium may be corrosive substances, carbon dioxide, natural and liquefied gas and ammonia. The differences in the characteristics of the steel flange valve from cast iron and brass analogues are primarily related to pressure and operating temperature. The values of these parameters are 6,3 MPa and +425?C respectively.
Strength characteristics of valves, made of steel, allow them to be used in high pressure mains
On a side note! Such indicators determine the possibility of using this device in highly stressful conditions, there, where high pressure and very high temperature.
One of the significant advantages of steel valves compared to cast iron products is less weight. This simplifies the requirements for the technical characteristics of the pipeline design, and there is no need to install special fittings and additional elements.
Stainless steel is usually used to make a steel flange valve. Frame, usually, is made of alloy steel of the A20 and A25 brands. However, there are technologies for using metal for this purpose without alloying components.
The diameter of the conditional passage of such a part reaches 100 mm. Therefore the steel flange valve can be established in the pipeline with incredibly big expense of the working environment..
By type of housing, such devices are passable and angular. The first type is used on straight sections of the highway. Its disadvantage is the high hydraulic resistance. The scope of the angle valve is the connection of perpendicular pipelines.
There is also a separate category of steam check valves. They are used on pipelines to transport the working medium with a temperature above 400?WITH. The advantage of the steam flange valve is the absence of stagnation zones. But there were also shortcomings. The steam valve has large dimensions and weight.
Check valves are used for straight sections of the highway
Brass valve. Used on pipelines, transporting liquid and vaporous working medium. Asbestos stuffing box stuffing, and paronite sealing rings. Manual control method, where the role of the handle is played by a flywheel. Dimensions and weight of the most popular modifications of the brass valve are presented in table №1.
Table 1
| Height, mm | Length, mm | The diameter is conditional, mm | Mass, kg |
| One hundred and eighteen | One hundred forty two | Fifty | 1,58 |
| One hundred and six | One hundred and ten | Fourty | 1,19 |
| Ninety-five | Ninety-five | Thirty-two | 0,67 |
| Eighty six | Eighty | Twenty five | 0,44 |
| Eighty | Sixty-five | twenty | 0,30 |
| Eighty | Fifty-five | Fifteen | 0,25 |
The gate is pig-iron. The case is made of malleable or gray cast iron. The locking unit is a complex multicomponent structure. It includes the following details: stuffing box, flywheel with threaded rod and spool. A feature of the cast iron flanged valve is that, that almost all the details of its locking unit are steel. The exception is made only for the sealing element of the spool of the cast iron valve. At its end you can see the leather, fluoroplastic or rubber gasket.
In conclusion, it should be noted, that shut-off flanged valves are very undemanding to environmental conditions. They can be used in large enterprises, and be installed in the basement of a residential building.