Shut-off valves

Shut-off valves: ball valves, butterfly valves, gate valves, check and stop valves

Shut-off valves are a type of pipeline valves, the main function of which is to regulate and open / close the working flow (liquid, gas, bulk substances). With the help of stop valves, the pressure in the pipeline is regulated, the direction of flow is changed, the supply of flowing substances is temporarily stopped (during installation or repair of the pipeline) or the working flow is completely blocked.

Shut-off valves are designed for:

• pipelines supplying gas and water, as well as drainage waste for both residential and industrial buildings;
• pipelines used in the oil and gas and chemical industries for the transportation of corrosive substances. Particularly stringent requirements for tightness and corrosion resistance are imposed on this type of fittings;
• pipelines used in domestic water and heat supply systems, as well as sewer systems.

For the manufacture of valves, stainless steel, cast iron, bronze, titanium, brass, ferritic and alloy steels are used - it depends on the working environment, the internal pressure of the pipeline, and the temperature conditions in which the pipeline is operated.

Types of valves

There are several main types of shut-off valves: valves, gate valves, taps, butterfly valves. Structurally, these types are similar: a closed sealed case with a shut-off unit, in which there are two (sometimes more) ends for connection to the pipeline. The assembly consists of a seat and a plug that are in constant contact with the sealing surfaces.

The main difference between the types of valves in their functions and the main tasks performed:

• Gate valve - shut-off valves designed to open / close the working stream. Optimal for pipelines with high working pressures and temperatures.
• Butterfly valves are shut-off and control valves that change and stop the flow of the working flow. Optimal for large-diameter pipelines, but not recommended for pipelines with pressures above 2.5 MPa.
• Ball valves ball valve - shut-off and control valves with quarter-turn control. Optimal for opening / closing a working stream, but not recommended for regulating the flow.
• Shut-off valves globe valve - shut-off and control valves of linear movement, starting / stopping and regulating the flow of the working flow. Differs in minimal hydraulic losses in the mode of full opening of the crane. Ideal as a shut-off element for non-critical flow resistance.
• Check valves check valves are shut-off and control valves of non-return linear movement. Recommended for flow control in wastewater systems and in pipelines with different pressures.
• Plug valve plug valve is a rotary shut-off valve that starts / stops or regulates (rarely) the flow of the working stream. It is used in environments with high pressure, gaseous or liquid substances.
• Diaphragm valve diaphragm valve is a shut-off and control valve for linear movement. Depending on the type, it can perform both a shut-off-regulating (Weir (Saddle) type diaphragm valve) and only a shut-off function (Straight pattern diaphragm valve (Straight-through type valve)). They are used for vacuum and high pressure environments, but not recommended for operating temperatures above 180 ° C.
• Mesh filters filter strainer is an auxiliary pipeline fittings, the task of which is to clean the transported medium from solid impurities, dirt and small debris. Depending on the type, filters are used in pipelines with any operating pressure and any flow rate.

Classification of valves
Locking elements are classified according to several criteria.

Depending on the destination:

• narrow profile;
• general technical;
• industrial special;
• ship;
• transport;
• plumbing.
• Depending on the functions performed:
• throttle;
• shut-off;
• locking and regulating;
• reverse;
• irrevocably manageable;
• irreversible shut-off;
• protective;
• drain, etc.

Depending on the connection to the pipeline:

• welded (butt-welded) - used in the most critical or hard-to-reach sections of the pipeline, since they guarantee complete tightness of the overlap and high strength of the connection;
• flanged - used in pipelines when it is impossible (prohibited) to carry out welding or in those pipelines that are often fully or partially assembled / disassembled. Mainly used in main pipelines with a large nominal diameter;
• threaded (screwed (NTP)) - such elements with a tapered or cylindrical internal thread are used mainly in municipal services in pipelines of small diameters with low pressure;
• socket weld - used in pipelines of small diameters with low and medium working pressure.
• combined - used in pipeline systems with welding / thread, welding / flange connection.

Depending on the control method:

• hydraulic;
• electrically driven;
• manual control.

When choosing fittings for specific purposes, the following points must be taken into account:

• working medium (gas, oil, water, steam, bulk substances);
• chemical composition of the working environment (aggressive, toxic, slightly aggressive);
• pressure and temperature of the working environment (ultra-high, ultra-low);
• valve tightness requirements (increased, standard);
• pipeline diameter (large, small);
• control conditions (automatic, manual).

Also, the material for manufacturing the valves will depend on these data.

Application area of shut-off valves
About 80% of pipeline fittings are exactly the shut-off category.

Its scope is quite extensive:

• heating, ventilation, air conditioning, fire extinguishing systems;
• thermal and nuclear power plants;
• water, oil, gas pipelines and steam pipelines;
• river and sea vessels;
• household gas stoves, boilers, shower cabins, etc.;
• water purification systems;
• sewerage systems, etc.

The benefits of shut-off valves

All types of valves have the following technical characteristics:

• simple and reliable design;
• high tightness of the flow shut-off;
• small construction weight and length;
• simple form of the flow path, without stagnant zones;
• maintainability and ease of maintenance;
• convenient control system;
• durability.

You can order and buy valves from URAL TRADE . We supply high-quality rolled metal products from leading European manufacturers. All products are accompanied by a package of certificates confirming compliance with regulatory world standards.