Pipeline shut-off valves and their arrangement. Types of pipeline fittings - classification, use

Pipeline fittings are a range of structures installed on pipelines for the purpose of controlling the transported medium by changing the actual cross-sectional area of the pipe. Technical requirements and nomenclature of pipe fittings of industrial and domestic type are given in the regulatory document GOST No. 52720 “Pipeline fittings”.

This article presents a classification pipeline fittings. We will consider its varieties, functional purpose, design features and study the marking of reinforcement products.

Contents of the article

Classification of pipe fittings

According to the provisions of GOST, pipe fittings divided into groups based on the following factors:

functional purpose;
scope of application;
device control method;
method of connection to the pipeline;
sealing principle.

The main classification parameter is the functional purpose; according to it, the following types of pipeline fittings are distinguished:

Shut-off valves are structures designed to completely shut off the flow of medium circulating through a pipeline. Shut-off products, in turn, are divided into drain valves (used to remove the transported medium from the pipeline) and control valves (blocks the flow and supplies the working medium to instrumentation).
Control valves - used to regulate the throughput of a pipeline. It is divided into throttle valves - due to an increase in hydraulic flow resistance, and shut-off and control valves - which combines the functions of two types of fittings and is the most commonly used pipe fittings today.
Protective (cut-off) valves - installation of shut-off valves is carried out to protect the equipment connected to the pipeline and the pipeline itself in emergency situations. The fittings block and disconnect the failed part of the pipeline from the circulation ring, which makes it possible to carry out the required repair work. A type of protective fitting is one that prevents the possibility of reverse flow of the circulating medium.
Safety valves are structures that automatically relieve excess pressure in the system, which protects equipment and the pipeline from overloads.
Distribution fittings - installation is carried out in two adjacent pipelines if it is necessary to combine and mix their flows.
- structures used for either routing a highway into several channels. This group includes all kinds of bends, crosses, etc. The material of manufacture of the connecting fittings corresponds to the material of the pipeline (production of both steel and polypropylene and polymer products has been established).

Depending on the scope of application, all pipeline fittings are divided into industrial and household. Household fittings are used for gas pipelines, water pipes and heating pipes. The class of industrial fittings, in turn, is divided into the following groups:

steam;
water;
oil;
chemical;
gas;
food

A separate subgroup includes ship fittings used on military and civilian ships, which have an increased reliability class.

According to the control method, pipeline fittings are divided into two types - automatic and controlled. Controlled valves can have several types of drives:

manual drive;
mechanical drive (electric, pneumatic, hydraulic or electromagnetic type);
remote drive - a control structure that is remote from the valve and connected to it through a transmission (shaft, cable, gears or bearings)

Depending on the method of connection to the pipeline, pipe shut-off valves are:

flanged;
coupling;
tsapkova;
fitting;
welding

The last classification factor is principle of sealing fittings, according to which structures are divided into:

stuffing box - at the junction of the fittings and the end part of the pipeline, seals made of asbestos, graphite, fluoroplastic or;
bellows - instead of elastic materials, metal ones are used for sealing;
membrane - structures in which the membrane simultaneously performs a sealing and locking function;
hose - a compressible rubber hose is used as a sealing material.

Marking of pipeline fittings

Marking of pipeline fittings is carried out in accordance with the provisions of GOST No. 4666-75 “Pipeline fittings”. The marking consists of a series alternating letters and numbers, example - 30s941nzh2, where:

30 — type of fittings (valve);
c — material of manufacture (carbon steel);
9 — drive type (electric);
41 — model number;
nzh - type of sealing material (stainless steel bellows seal);
2 - execution option.

You can find a breakdown of each nomenclature component of the marking in the tables of TsKBA (Central Design Bureau of Valve Engineering).

Operating principle of pipeline fittings (video)

Types of pipeline fittings

Shut-off pipeline valves, the most common type of fittings, have several design options. Pipe shut-off valves are divided into the following types:

damper (butterfly valve);
valve (valve);
tap.

Every person, no matter where he lives, uses shut-off valves in his life. Any pipelines are always equipped with devices that make them safe.

Shut-off pipeline valves are designed to allow a person to control the flow of the working medium moving through the pipeline. Moreover, it does not matter at all what exactly the working medium is - water, steam, gas, oil products, aggressive substances - without shut-off valves, operation of the pipeline is impossible.

Types of shut-off valves

The materials most commonly used for the production of locking devices are brass, bronze, steel and

The main characteristics of locking devices are:

diameter of the pipeline connected to it;
the amount of excess pressure in the pipeline at a temperature of +20 degrees.

There are several types of devices related to shut-off valves:

dampers;
valves;
valves.

In order to determine the required type of fittings, you need to know under what conditions it will work. This is necessary because water pipelines, gas lines and systems designed for pumping aggressive substances are used completely different types equipment.

Types of shut-off valves

Shut-off valves are widely used in the construction of any pipelines. They can be attached to pipes using one of two types of connections: flange or coupling. It happens that tap pipes are welded to pipelines.

All taps are divided into:

cork;
ball

A plug valve is shaped like a truncated cone. This is the most ancient type of locking device.
Currently, these devices are mainly used, the working environment of which is:

neutral and fuel gases;
phenol;
oil;
lubricating oils;
water.

The big disadvantages of these cranes are:

to operate the crane, a large torque is required, which requires the use of a gearbox;
to avoid sticking of the faucet to the body, its constant maintenance is necessary;
the tightness of the tap depends on such a complex operation as rubbing it against the body;
there is a high probability of uneven wear of the device, which threatens the tightness of the system.

A ball valve is a device consisting of a body and a plug. The body is stationary, and the plug rotates, allowing the working medium to pass through or blocking it.

Ball valves vary depending on the surface shape on:

conical;
spherical;
cylindrical.

A wide range of materials are used in the manufacture of ball valves: titanium, cast iron, steel, zinc, ceramics, plastic.
Their main areas of application are:

for water supply and heating;
devices for connecting household appliances where periodic water supply is required;
pipeline junctions and branches;
industrial and food installations.

In addition, the reliability of the design of these locking devices, their resistance to temperature changes and some chemicals, allow them to be used where the working environment is aggressive substances.

Among the important characteristics of ball valves there is such an indicator as the installation method. According to him, taps can be:

coupling – used in pipelines of small diameter;
flanged – which are used in pipelines with a diameter greater than 50 mm, withstand quite heavy loads (can be used in industry);
fitting – easily withstand repeated disassembly, therefore they are used mainly in industrial installations;
welded– fixed exclusively by welding, used in aggressive environments;
combined – combine several mounting options.

Gate valves

They are used mainly on large-diameter pipelines subject to low pressure of the working medium.

The shutting element of the damper is a disk that is capable of rotating around its own axis, located perpendicularly or at an angle to the direction of movement of the working medium. The tightness requirements for dampers are significantly lower than for taps.

The damper control can be:

using an electric drive;
using a hydraulic drive.

As a rule, the damper body is made of cast iron, and the rotary disk is made of steel.

Resistance of cast iron to impact chemical substances allows the installation of dampers where alkalis, acids and corrosive wastes are pumped.

The valves are cut into the pipeline using flange connection or welding. This type of shut-off valve requires virtually no maintenance.

The peculiarity of the dampers is that they are able to pass through the working medium containing solid particles.

Gate valves

They are designed to block the flow of a non-aggressive working environment with high pressure and temperature. They are most often used in main pipeline systems related to housing and communal services, water and gas supply, oil pipelines, and energy facilities.

The shut-off element of the valve moves perpendicular to the direction of movement of the working medium.
Z The sliders, depending on the design of the working body, are divided into:

wedge - due to strong friction when closed, they may lose their tightness over time;
gate (parallel) - used for one-way flow of the working medium with not too high requirements for tightness (used on pipelines transporting wastewater, sludge and other media with mechanical impurities).

The most commonly used valves are equipped with an electric drive, which allows you to quickly shut off the flow.

The advantages of valves are:

small hydraulic resistance;
simplicity of design;
possibility of use in various conditions;
the ability to pass flow in any direction;
high tightness;
high maintainability.

Shut-off valves

This is a widely used shut-off valve designed to completely shut off the flow of the working medium. The valve cannot be adjusted

A device such as a valve must always be in a fully open or fully closed state. It can be installed in any position.

The valve consists of a spool, which is located on a descending spindle. When the valve closes, the spool moves down onto the seat and shuts off the flow. In this case, the valve shut-off element moves parallel to the flow, which prevents the occurrence of water hammer.
Based on the type of sealing, valves are divided into:

stuffing box;
bellows;
diaphragm.

These devices are equipped with pipes through which they are cut into the pipeline. If the valve is designed to operate under high pressure conditions, it has thick walls and is attached to the pipes by welding.

Valves large sizes can use flanges, and small ones - using coupling connections. The valves can be controlled either manually or using an electric motor. There are options with remote control.

Cast iron coupling valves are used when pumping air or water, the operating temperature of which does not exceed + 50 degrees. Brass coupling valves are lightweight and have proven themselves in high-pressure systems. They are not afraid of pressure changes.

Cast iron valves with an electromagnetic drive are used on pipelines through which water or air with a temperature of no more than + 50 degrees moves.

Fittings for aggressive environments

When working in aggressive environments, valves are most often used due to the hermetically sealed connection between the seat and spool and the almost complete absence of friction.

Brass performs very well in aggressive environments, which is why brass sleeve valves are most often used in liquid environments.
At high temperatures of the working environment, it is better to use bellows valves that can withstand heating up to +350 degrees. They are very reliable and guarantee high tightness in those connections where leakage of the working medium into the atmosphere is unacceptable.

In aggressive environments, the corrosion resistance of shut-off valves is very important, which is why porcelain flanged valves are often used here.

Its body is made entirely of porcelain, and the anti-corrosion coating is a glaze applied to its surface.

Diaphragm valves with a protective rubber coating are also found in complex ones.

Thus, knowing the features of shut-off valves, it is not so difficult to select those products that are necessary for work in specific conditions.

When building modern housing, it is impossible to do without installing pipeline systems. Through the pipeline, water, gas, heat are supplied to the houses, and sewage is removed from the house. For quality work pipeline, controlling the flow of water or gas flowing through it, installing branches or outlets, pipeline fittings are required. In order for your pipeline to function without problems, you need to understand the characteristics and purpose of these devices.

When installing pipelines, it is necessary to equip branches, bends, connections, regulate pressure, mix liquids or gases in the pipe; for this, pipeline fittings are used - a special type of connecting and adjusting products for the pipeline.

The scope of application of fittings is different, therefore the following types are distinguished:

shut-off pipeline valves - used when it is necessary to shut off the flow of liquid or gas in a pipe, for example, a valve or damper;
control valves - a subtype of shut-off valves used to regulate (reduce or increase) the volume of liquid or gas flows in a pipe, for example, a valve or faucet;
safety fittings - used to discharge excess steam or water if the pressure in the pipe exceeds the permissible value. Serves to protect pipes; such devices include safety valves;
distribution and mixing fittings are bends, adapters, tees used to distribute flows through pipes and mixers for mixing flows, for example, water faucets for a bathroom or kitchen;
condensate drain - designed to remove the resulting condensate and superheated steam.

Characteristics of pipeline fittings

The modern market for pipeline products includes a huge number of domestic and foreign manufacturing companies, as well as a range of pipeline products that differ in functionality and characteristics. So if you need pipeline fittings during the construction of a pipeline, buying them will not be difficult.

In order for pipeline fittings to serve for a long time and reliably, it is necessary to take a responsible approach to its choice, to clarify the load with which your pipeline and its parts will operate. The choice of fittings depends on the parameters that determine the technical characteristics of the devices.

The main parameters by which pipeline fittings are selected are:

nominal diameter of the pipe (marked DN), or, in other words, internal diameter. This value determines the throughput of the pipe or fittings;
conditional pressure (marked PN) - an indicator of the maximum possible pressure at which the valves are operated in normal mode for a long time, calculated at a temperature of 20⁰C;
working pressure - calculated at normal temperature conductive medium and denotes the highest excess pressure value at which the valve operates in a given mode for a long time;
design pressure - predicted pressure expected when exposed to minimum or maximum temperature;
temperature regime - the accepted operating temperature under which the fittings and the pipeline itself will be operated;
pipeline throughput - a characteristic that determines the cross-section of the reinforcement;
valve tightness level - affects the choice of material from which the fittings are made;
options environment.

For the successful selection of pipeline fittings and the operation of the pipeline, all of the above characteristics are important. If known specifications pipeline, its purpose, expected loads, mode of use, then selecting the necessary pipeline fittings for it will not be difficult.

Types of pipeline fittings

Pipelines are built for transportation various substances- steam, water, oil, sewer, ventilation. Naturally, there are different pipeline fittings for each type.

The material from which the body parts are made can also vary. Accordingly, the fittings are:

steel pipeline fittings - the material is carbon and alloy steel;
fittings made of corrosion-resistant steel;
fittings made of gray, ductile or high-strength cast iron;
non-metallic reinforcement - based on polyvinyl chloride, vinyl plastic or other polymer materials;
ceramic fittings;
glass fittings.

The choice of material for pipeline fittings depends on the purpose and parameters of use of the pipeline. For example, fittings made of gray and ductile cast iron cannot be used if they are subject to sudden temperature changes or vibration.

Pipeline fittings also differ by area of application.

In industrial production, when installing water pipelines, heating systems, and steam pipelines, pipeline fittings for general construction purposes are used. Usually these are mass-produced fittings (valves, shut-off valves, pressure valves, control valves, steam traps) from well-known and well-established companies. There are a variety of pipeline fittings on the market, the price of which depends on the quality and reputation of the manufacturer. For example, among the foreign brands that produce fittings, Zetkama, Polix, ARI-Armaturen are known.

Industrial fittings for use in special operating conditions, used in pipelines that will be operated at low or high temperatures, at high blood pressure, using corrosive substances, toxic and radioactive liquids.

Plumbing fittings are used in the installation of household pipelines - supplying gas to household gas stove, plumbing and bathroom equipment with mixers, shower units. For these works they are used Ball Valves, valves, pressure regulators, check valves, filters.

There are also special-purpose pipeline fittings that are used in special conditions. technical requirements operation, for example, in experimental facilities and is usually made to special order.

If you understand the purpose of the pipeline, and accordingly, the purchased fittings, think about the issue of connecting to the pipeline. Depending on the connection option, the following types are distinguished:

flanged pipeline fittings, for connecting which to the pipeline flanges are used;
coupling fittings - connecting fittings with internal thread, usually used when the nominal diameter is no more than 40 mm and when using a pipeline for neutral and non-flammable substances;
pin fittings - used under the same conditions as coupling fittings;
fitting fittings - fittings and fittings that are used to make turns, branches, and transitions to another diameter in pipelines;
welded fittings - used in the installation of steel pipelines and pipelines made of plastic materials and ceramics. Often the need to use this type of connection is caused by the danger of the medium being carried through the pipeline, and welded connections eliminate the possibility of leakage.

The choice of pipeline fittings is also influenced by the need to use regulation; it can be manual or automatic. Depending on this parameter, controlled and autonomous valves are distinguished. The controlled valves are equipped with a manual drive, or, depending on the design, the drive can be mechanical, electrical, hydraulic, or electromagnetic.

In order for pipeline fittings to function for a long time and safely, when choosing, it is necessary to be guided by its functional purpose. Naturally, when choosing fittings, the buyer looks not only at the technical characteristics, but also at its cost, durability, ease and availability of use and maintenance. Among the pipeline fittings products on the market today, you can select devices that meet all requirements.

Pipeline products and pipeline fittings have now become the most popular metal products, and with the growth in construction there is every chance to increase their production and sales.

The world of pipeline fittings is huge and diverse, and at first acquaintance it may seem chaotic and obscure.

But if you understand the principles of its classification proposed in regulatory documents, it will become well structured and orderly. Classification is a very convenient and useful tool that assigns each product its place and positions it relative to other products, the tasks that it must solve, the fundamental design, design features, materials used in it, etc.

In relation to pipeline fittings, we can talk about two basic principles of classification ─ types and types of pipeline fittings.

Types of pipeline fittings

A kind of watershed between various types The valve is its functional purpose, depending on which it is divided into several large segments: shut-off, return, safety, distribution and mixing, control, shutdown.

It is one of the most common and sought after types. Thanks to its use, it is possible to completely block the flow of the working medium with one degree or another of tightness. Therefore, tightness and tightness life serve as basic indicators of the functionality and quality of shut-off pipeline valves.

In relation to shut-off valves, they speak of two states - “open” and “closed”. An intermediate position of the working body may not be provided.

The scope of its application is extremely wide and covers maritime transport, deep-sea vehicles, aviation and space technology, nuclear energy and, of course, the blood vessels of the Russian economy - main oil and gas pipelines.

A modern pipeline is a complex complex engineering structures, any malfunction of which, fraught with disruption of the normal course of the technological process, can lead to severe economic and environmental consequences.

The ubiquity of shut-off valves is clearly illustrated by the fact that by default the words “shut-off”, “shut-off” in combination with the type (more about types will be discussed below) of the valve are not used. For example, they don’t say “ gate valve", although gate valves are the most common type of shut-off valves.

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Check valves (it is not recommended to call them reverse valves) are used to automatically prevent the reverse flow of the working medium.
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The task of safety valves is to protect equipment from emergency excess pressure or other parameters of the working environment by automatically releasing its excess. Perhaps one of the most striking examples of safety valves is safety valve installed on a steam boiler.

Safety valves make a significant contribution to ensuring trouble-free operation and overall reliability of pipeline transport systems, industrial and power plants. It negates the consequences of working environment parameters going beyond acceptable limits, for whatever reason they occur: equipment breakdown, maintenance personnel error, internal physical processes or the influence of third-party factors.
***
With the help, the flow of the working medium is distributed in certain directions and mixed. However, a complete “division of labor” is possible. In this case, pipeline fittings intended only for distributing the flow are called distribution fittings, and those intended only for mixing it are called mixing fittings.
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A very important place in the general range of pipeline fittings is occupied by control valves, which provide accurate and reliable regulation of the parameters of the working environment, without which the organization of economical and safe technological processes and the formation of complex multi-component production chains is impossible.
Control valves in their “pure” form and in combination with shut-off valves provide conditions for the normal functioning of equipment and its good controllability at the most critical facilities, including nuclear power plants. Against the backdrop of increasingly complex operating conditions in the electric power industry (increasing initial parameters of coolants, increasing unit capacity of power plants), its relevance is only increasing.
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Shut-off valves (sometimes called protective valves) are designed to shut off the flow of the working medium when its flow rate exceeds a specified value, not provided for by the technological process, due to a change in the pressure drop across the sensing element. The difference from safety pipeline valves is that the flow is not bleed, but only a specific element is turned off.
Combined fittings include fittings that combine the functions of the above types. They have “telling” names, from which it follows what types of fittings they combine. For example, shut-off and regulating fittings (it is not recommended to call shut-off-throttle) or check valve fittings
Irreversible-constipated And irretrievably controlled fittings perform the function of check valves, in which forced closing or restriction of the stroke of the locking element can be carried out, and in irreversible-control─ also limiting its progress.

Types of pipeline fittings

There are even fewer main types of fittings than there are types - only four: valve, faucet, butterfly valve. Belonging to each of them is determined by design features, expressed in the direction of movement of the locking or control element relative to the flow of the working medium.

The type of valve in which the locking or control element moves perpendicular to the axis of the flow of the working medium is called a valve.

A valve (it is better not to call it a valve because of the ambiguity and vagueness of this term) is a type of fitting in which the locking or control element moves parallel to the axis of the flow of the working medium.
In a faucet, a locking (regulating) element, made in the form of a rotating body or part thereof, rotates around its own axis (this may be preceded by a reciprocating movement) arbitrarily located in relation to the direction of flow of the working medium.
In a butterfly valve, a disk-shaped locking (regulating) element rotates around an axis located perpendicularly or at an angle to the direction of flow of the working medium.
Each of these types lends itself to more detailed structuring. Thus, valves, depending on the design of the seat and shutter, are wedge and parallel, with a retractable or non-retractable stem (spindle).
Valves with a valve in the shape of a disc are called poppet valves, and valves in the form of a conical needle are called needle valves. In addition, valves can be single-saddle and double-saddle.
Valves are divided into conical, cylindrical, and ball.
Each of the listed types of pipeline fittings has its own advantages and disadvantages, and in accordance with them, more and less preferable areas of application.
Thus, a feature of valves is their significant construction height (the size from the horizontal axis of the flow section of the valve body to the upper end of the spindle, rod or actuator when the valve is fully open), small construction length (the linear dimension of the valve between the outer end planes of its connecting parts to the pipeline or equipment) , low hydraulic resistance, high force on the shutter drive, rather leisurely operation, and with contaminated liquids - wear on the seat surface. Valves cope much better with the role of shut-off valves than control valves.
Unlike gate valves, the most common type of pipeline fittings ─ valves ─ have a low construction height, large construction length, fast response, significant hydraulic resistance, and high tightness. Valves are included in the design of most regulators.
Cranes, like valves, have a low construction height and quick response. And like valves - short construction length.
The disc valve (it is more correct to refrain from the name “valve”) has a small construction height, construction length, force on the valve drive, hydraulic resistance and fast operation.

Types of pipeline fittings

Just as in mathematics sets are divided into subsets, types of reinforcement can be structured into varieties.

● varieties by purpose and area of application

The largest of these “subsets” are varieties by purpose and area of application.
Features of operation can be used as classification characteristics - vacuum fittings, cryogenic fittings; or operating features, for example, shut-off valves (shut-off valves with minimal response time). The basis for separation is also: installation location (receiving fittings ─ check valve installed at the end of the pipeline in front of the pump) and the presence of additional options (heated fittings).
But the most compelling reason to separate the pipeline fittings for varieties ─ its purpose: control valves, anti-surge valves, pressure-reducing valves, drain valves, trial fittings, etc.
The areas of application of pipeline fittings cannot but impose special requirements on them. The fittings used in the gas industry must be sealed due to the high fire and the explosion hazard of the working medium in this case - gas.
Pipeline fittings for the oil production and oil refining industries, due to the fairly high chemical aggressiveness of oil, must have increased corrosion resistance. Even more aggressive environment, including concentrated acids and alkalis, affects pipeline fittings used in the chemical industry.

● varieties for connection to the pipeline

Based on this feature, the fittings are divided into flanged, wafer, wafer (i.e. wafer installed between the pipeline flanges). The coupling fittings are equipped with connecting pipes with internal threads. Weld fittings - pipes for welding to the pipeline. The fittings also have connecting pipes.

● variations in the design and shape of the body

Based on the position of the pipes, we can talk about through fittings (the connecting pipes are coaxial or mutually parallel) or corner fittings (the axes of the inlet and outlet pipes are located perpendicular or not parallel to each other). Fittings with offset axes of pipes are also produced.

If the cross-sectional area of the flow part less area inlet pipe openings ─ thispartial borefittings If approximately equal to or greater than ─ full bore fittings.
According to the method of manufacturing body parts, cast fittings are distinguished, lithowelded, cast-stamp-welded, stamp-welded.

● varieties by type of seals

Valves in which the sealing of a stem, spindle or other moving element relative to the environment is ensured by a stuffing box seal are called stuffing box fittings.

Valves that do not use a gland seal for sealing are called glandless valves. Bellows and membrane fittings fall into this category.

The alphabets of most languages of the world contain several dozen letters. But this did not stop them from accumulating hundreds of thousands of words, using which millions of books were written. So it is with pipeline fittings ─ its incredible diversity consists of a relatively small number of classification units, measured in units, sometimes tens. And it did not appear by chance, but due to the need to answer a huge number of questions, to find a solution algorithm large number tasks.
Pipeline fittings are subject to such a wide range of requirements that often the technical solutions with which to achieve them come into conflict with each other, and the emergence of a large number of different designs is one of the ways to overcome this. And the classification ─ The best way You won’t get lost in this diversity.

The functioning of the pipeline requires its constant maintenance. For this they use different types pipeline fittings - safety, drain, shut-off, etc. For example, to partially or completely block the movement of the working medium in the system, shut-off valves for pipelines are used. The characteristics and types of pipeline fittings will be discussed in this article.

Types of fittings for pipelines

The following types of pipe fittings are distinguished:

regulating;
shut-off and regulating;
irrevocably constipated;
constipation;
safety;
reverse;
irrevocably controlled;
mixing and distribution;
drainage (drainage);
outlet;
disconnecting (protective);
reduction (throttle);
phase separating;
control.

As you might guess, each type of product is intended for specific purposes, to which the design of pipeline fittings also corresponds.

For example, shut-off pipeline valves are used to block the movement of a working medium (or a set of media) for the purpose of carrying out preventive work on the network.

Fuses serve to protect the pipeline from exceeding the operating pressure, as a result of which the system may fail, by discharging excess fluid.

Control valves are designed to maintain the required amount of media by changing its flow rate.

The occurrence of return flow, which reduces the performance of the system, is prevented by return elements (in particular, non-return-shut-off and non-return-controlled).

Reset from pipeline system working environment is carried out through the use of descent, or drainage, devices.

Phase separation (provided that several phase states of the medium move in the pipes) is carried out using phase separating elements.

The operating pressure in the system is reduced, if necessary, through the use of pressure-reducing valves.

Types of pipeline fittings

The scope of use of pipeline fittings is quite wide; it is used in all types of industrial pipelines, including in technologically hazardous industries (when moving toxic, explosive, environmentally hazardous substances). Therefore, the characteristics of pipeline fittings must fully comply with state safety standards. Typically, large enterprises are engaged in the production of such products.

In accordance with the planned use of pipe fittings, the following products are distinguished:

General technical application.
For special conditions.
Industrial special.
Ship and transport.
Industrial plumbing.

General-purpose products are mass-produced and can be used in any field of production.

Shipping and transport operations are carried out in different climates and with varying dimensions of vehicles, which must correspond to ship or transport fittings.

Industrial plumbing elements, as you might guess, are used in the installation and operation of industrial plumbing.

Conditions for the production of fittings

The material used to manufacture pipeline fittings is determined by its future area of application. If the system (or section of the system) will operate at pressures up to 1.6 MPa, ductile cast iron is used; if more - steel. For small cross-section pipelines, high-quality copper alloys are used, which prevent corrosion of elements and sticking of fittings to the pipes.

It should be noted that the production of reinforcing elements is a complex and high-tech matter, and therefore must be carried out on special industrial equipment.

To produce products you need:

bake;
special purpose press;
diagnostic machine;
table on which assembly is carried out;
lathe;
drilling machine;
conveyor;
air compressor for painting products;
auxiliary tools and devices.

Locking devices: classification and application

The main types of shut-off valves for pipelines are valves, valves, flaps, taps and valves. Gate valves are characterized by the movement of the locking element at right angles to the longitudinal axis of the pipe, while valves are characterized by parallel movement.

Valves

It is possible to use valves on shut-off products with a diameter of up to 0.3 m. They are often used in the final (dead-end) sections of the system during repairs. The locking element, often a body of rotation or part thereof, rotates around an axis located at an arbitrary angle relative to the axis of the pipe. Valves can be used not only as shut-off valves, but also as control valves.

Valves

Gate valves are short-length shut-off elements designed to operate in systems with low hydraulic resistance.

By design, they are wedge (with a composite, elastic, solid wedge) and parallel (gate). In systems with low pressure, valves of the latest type are used.

The main purpose of valves is to perform locking functions; in most cases they are not used as regulatory elements. During operation, the valves can be set to two possible positions: closed or open.

It is best to use such elements in full-bore systems, that is, in the absence of a reduction in the cross-section of pipes in the nozzles. For example, gate valves are ideal for use in main pipelines, where the working environment moves continuously and at high speed.

A distinctive design feature of the valve is the presence of a spindle, which, depending on the design, extends or not.

As already noted, there are two main types of valves: gate valves and wedge valves.

The design of the gate elements includes a metal wedge that, when moving, cuts foreign elements of the working environment. Gate valves are equipped with pipelines for fecal wastewater, pulp and paper production, etc.

If it is necessary to carry out periodic repairs of system elements, wedge valves are installed, consisting of a cast-iron body, inside of which a rotating spindle connected to the wedge is installed. Wedge valves are used when servicing systems for transporting gases and liquids that do not react with the pipeline material. The body and cover of such products are welded from parts cut from corrosion-resistant or carbon steel sheets.

The closing and opening of the valves can be controlled manually or using electric drives - hydraulic, pneumatic or electric. When adjusting the position of the element manually, you should also take care of installing a gearbox, which allows you not to spend too much effort on the process.

Valves

The purpose of the valves is to open and close under certain conditions, for example, when a certain pressure level is reached or the direction of movement of the working fluid changes.

Products are divided into single- and double-saddle, and usually the second type is used in production, which simultaneously performs distribution and control functions.

Based on the direction of flow of the working medium, valves are divided into angular (the direction changes by 90°), through (the direction does not change) and straight-through (the line of movement of the medium is straightened).

To completely block the flow inside the pipes, shut-off valves are used. This fittings ensure maximum reliability and tightness of the system.

If there is a need to prevent a change in the movement of the working medium (for example, if the pump fails and the carrier channel is damaged or broken), check valves are used.

With the help of control valves, you can control the amount of liquid or gas supplied to the system by changing the size of the inlet.

Shut-off and control valves, as the name implies, perform two functions simultaneously.

All valves, provided they are of proper manufacturing and installation quality, are suitable for use in vacuum, corrosive environments, elevated temperatures and pressure. These pipeline fittings are relatively easy to repair and maintain.

Cranes

A more universal option for pipeline fittings is taps. They can be used as shut-off, control or distribution devices. The taps are suitable for any, including viscous, liquids and gases. Repairing these devices requires a lot of effort and experience.

Valves consist of a valve (or plug) of spherical, cone-shaped or cylindrical geometry, with a hole in the center, and a body. These locking elements are made from brass, bronze, cast iron and steel, and in the case of more aggressive internal conditions - from porcelain or special plastic.

Cranes are usually divided into groups depending on:

direction of flow and number of nozzles (through, three-way, angled, multi-pass);
the principle of shutter movement (with spin, or lifting, or with rotation, without lifting, shutter);
control method (manual, with electric, pneumatic, hydraulic drives);
shutter geometry (needle, cone, ball, cylindrical);
method of ensuring tightness (stuffing or tension).

The main advantage of the tap is the ability to regulate the volume of flow. If the valve operates only in two modes - open or closed - then the valve device allows, by changing the position of the valve opening relative to the axis of movement of the working medium, to achieve a complete cessation, strengthening or weakening of the flow. Therefore, the tap can serve as both a shut-off and a regulating device.

Shutters: practice of use

Gates are the most important part of shut-off valves of any type. It is thanks to the serviceability of the valve that timely and complete (or, if necessary, partial) blocking of the movement of liquid or gas flow in the pipeline is possible.

Accordingly, if the valve is faulty or poorly manufactured, the consequences can be anything - from a minor, harmless leak, eliminated by simply replacing structural elements, to a full-fledged environmental disaster or explosion of the carrier. Therefore, special attention is paid to the material used to manufacture the valves and their operating conditions.

The most common type of valve is a butterfly valve. They are used in heating systems, water supply, steam supply, non-aggressive working environments or petroleum products. Flange valves are also used, distinctive feature which is the presence of a flange in the design.

Gates can be made of cast iron, but the use of steel products (alloy, stainless or carbon steel) is preferable.

Steel valves have a number of significant advantages:

operation at temperatures down to -60°C is possible;
such valves can operate in environments with temperatures up to 700°C;
designed for use in aggressive working environments;
withstand high pressure (up to 10 MPa).

How rotary shutter mechanisms differ:

ease of installation and repair;
compactness (they can be mounted in confined spaces);
small, compared to gate valves, weight and dimensions;
ease of replacement when the product wears out and has a long shelf life;
low price;
no risk of jamming or sticking during use.

We can say that shut-off valves, with their simplicity and relatively low price of products, are not only the most useful element of the pipeline design, but also the main guarantee of the safety of both the operation of the system and the health and life of operating personnel. After all, it is thanks to the shut-off elements that you can stop the leak of a dangerous liquid or poisonous gas in time and block the movement of the medium at the desired point, without disrupting the entire operating cycle of the system.

Therefore, the selection, quality and installation of shut-off valves should be approached as responsibly as possible, basing your decisions not only on the price of the product or country of origin, but also on pre-made calculations. And, of course, we must not forget about timely maintenance and scheduled replacement of elements that are so important for any pipeline.