Digest - industrial safety. Working, design and test pressure

Page 1

The test pressure during hydraulic testing of pipelines is maintained for 5 minutes, after which it is reduced to the working value. At operating pressure, the pipeline is inspected and the welded seams are tapped with a hammer to identify welding defects. The results of the pipeline test are considered satisfactory if during the test there is no pressure drop on the pressure gauge, and there are no signs of rupture, leakage and fogging in the welds, pipes, housings, fittings and other elements.

The test pressure is maintained for 5 minutes, after which it is reduced to the working one. At operating pressure, the pipeline is inspected with tapping of the welds with a hammer weighing not more than 0 5 kg. The results of the hydraulic test are considered satisfactory if the pressure has not decreased, and there are no signs of rupture, leakage or sweating in the welds, pipes, valve bodies and other parts.

Test pressure during hydraulic testing of pipelines must be maintained for 5 minutes, after which the pressure must be reduced to working pressure. At operating pressure, the pipeline is inspected and the welds are tapped with a hammer weighing no more than 15 kgf.

The test pressure must be maintained for 5 minutes, after which it is reduced to the working one. At operating pressure, the steam pipeline is inspected and the welded joints are tapped with a hammer weighing no more than 15 kg. A hydraulic test is considered satisfactory if there was no pressure drop on the pressure gauge during holding the test pressure in the steam pipeline and its elements (in welds, valve bodies, flange connections, etc.).

The test pressure for cylinders made of material with a ratio of tensile strength to yield strength greater than 2 may be reduced to 125 times the operating pressure.

Test pressure in the boiler must be generated by a hand pump. When using machine-driven pumps, a gradual and planned increase in pressure must be ensured.

Test pressure - excess pressure at which the reinforcement must be subjected to a hydraulic test with water for the strength and density of the material at a temperature not exceeding 100 C.

Trial pressure during hydraulic tests is assumed to be 125 rrab, but not less than rrab 3 kgf/cm.

Test pressure during hydraulic testing is selected in accordance with the conditional pressure. For all pipes, as well as fittings, flanges and studs supplied for installation, the manufacturer draws up a factory certificate, which indicates their design characteristics and the grade of steel used.

The test pressure for cylinders made of material with a ratio of tensile strength to yield strength greater than 2 may be reduced to 125 times the operating pressure.

The test pressure for cylinders made of material with a ratio of tensile strength to yield strength greater than 2 may be reduced to 125 times the operating pressure.

The test pressure for cylinders made of material with a ratio of tensile strength to yield strength greater than 2 may be reduced to 125 times the operating pressure.

The test pressure determined according to this table at a temperature from 200 to 400 C should not exceed the working pressure by more than 15 times, and at a wall temperature above 400 C - by more than 2 times. When testing high apparatuses, it is necessary to take into account the hydrostatic pressure of the liquid column, therefore, for example, when columns are tested hydraulically before installation in a horizontal position, then to the value of the hydraulic test pressure determined from Table. 3, add the hydrostatic pressure, which will be when the column is filled with water in a vertical position. In all cases, the stresses in the walls of the vessel during a hydraulic test should not exceed 90% of the yield strength of the material at 20 °C.

Industrial pipeline fittings - the name of a number of devices intended for installation on units, vessels or pipelines. The main operational task of pipeline valves is the control (distribution, shutdown, discharge, regulation, etc.) of the flows of gaseous, powdery, liquid, gas-liquid working media by increasing or decreasing the flow area.

Traditionally allocate two main operating parameters pipeline fittings: nominal size (nominal passage) and nominal (nominal) pressure.

Nominal passage (DN or Du) - a parameter by which the connecting elements of the pipeline are characterized: the nominal passage (nominal size of the reinforcement) is expressed in millimeters and is approximately equal to the internal diameter area of ​​the connected element.

* It is allowed to use for hydraulic and pneumatic devices.
** Not allowed for general purpose fittings.

Rated (conditional) pressure (PN or Ru) - the maximum overpressure in the system at a working medium temperature of 20 ° C, which allows to ensure the operational life of individual elements of the connecting fittings and pipeline. Designations and values ​​of nominal pressure must correspond to the ratings specified in GOST 26349-84.

The choice of nominal pressures less than 0.01 MPa is carried out from the R5 series, more than 100 MPa - from the R20 series (according to GOST 8032-84).

When marking pipeline fittings, the design of which was developed before 01/01/1992, it is allowed to use the designation of nominal pressure Ru. Nominal pressure designation PN6 can be used instead of designation PN 6.3.

Operating pressure Pр - maximum overpressure at operating temperatures that provide a given mode of operation of pipeline valves.

Trial pressure Ppr - excess pressure at which it is possible to carry out hydraulic tests of pipeline fittings and connecting elements for tightness and strength. Test pressure values ​​are determined according to GOST 356-80. If the value of the working pressure is below 20 MPa, then the test pressure will be approximately 1.5 times higher than Pp.

The classification of industrial pipeline fittings is carried out taking into account several technical, functional and operational characteristics.

Application area

Depending on the area and scope of application, the following types of industrial pipeline fittings are distinguished: general-purpose pipeline fittings, fittings for special working conditions, special fittings, transport and ship fittings, sanitary fittings.

1. General purpose pipe fittings is produced serially and is intended for operation in any spheres and branches of industry.
2. Pipe fittings for special working conditions designed for operation in power systems with high technological characteristics. In addition, industrial fittings of this type are used in the installation of pipelines, through which highly toxic and aggressive working media are transported.
3. Development and production special fittings carried out, as a rule, on special orders of individual departments or state enterprises. The scope of special fittings is ship power plants, objects of the Ministry of Defense, nuclear power plants, etc.
4. Transport and ship fittings produced for operation in the transport industry and, in particular, is used in shipbuilding. The reinforcement of this class is subject to increased technical requirements: in the production of transport reinforcement, the dimensions, weight of products, the possibility of operating the reinforcement in various climatic zones and other characteristics are taken into account.
5. Plumbing fittings It is used to complete and organize the functionality of various types of household equipment. Reinforcement of this type, as a rule, has a small diameter and does not cause any difficulties in operation. Production and release of sanitary fittings is carried out on production lines. In the production of sanitary fittings, special attention is traditionally paid to consumer characteristics and, in particular, product design.

Functional purpose

Depending on the functional purpose, the following types of industrial pipeline fittings are distinguished: shut-off, control, distributive-mixing, safety, protective and phase-separating.

1. Functional purpose stop valves- full opening or blocking of the flow in the pipeline. The operation of shut-off valves is determined by technological requirements.
2. Pipeline control valve used to control the parameters of working media by changing the flow rate. Control valves are various models of pressure regulators, liquid level regulators, throttling fittings, control valves, etc.
3. The main purpose dividing and mixing fittings(valves, cocks) – mixing of the working medium flows, redirecting the flows in the required direction.
4. Safety fittings used for automatic protection of pipelines and equipment from overpressure. During the operation of safety fittings, emergency situations are prevented by dumping excess working medium from the system. The most common types of safety fittings are impulse safety devices, safety valves, bypass valves, diaphragm rupture devices.
5. Functional purpose protective fittings(shutoff and check valves) - automatic protection of pipelines and equipment from failures in the technological process due to changes in the parameters of working media, changes in the direction of flows. During the operation of protective fittings, emergency situations are prevented without the release of excess working medium from the system.
6. Phase separating pipeline fittings will be used if it is necessary to organize automatic separation of working environments, taking into account their current state and phase. The most common types of phase separation fittings are gas separators, steam traps, air separators and oil separators.

Construction types

Depending on the design features, the following types of industrial pipeline fittings are distinguished: gate valves, valves (gates), taps, gates.

1. gate valve- constructive type of pipeline fittings, the movement of the working body of which is perpendicular to the direction of the flow of the working medium. As a rule, gate valves are most often used as shut-off pipeline valves.
2. Valve (valve)- a constructive type of industrial valves, the movement of the regulating or shut-off body of which is carried out parallel to the axis of the flow of the working medium. There is a variety of this type of fittings - membrane valves. In the design of a membrane valve, a membrane acts as a shut-off element, which is fixed between the body and the cover along the outer perimeter and performs the function of sealing the shut-off body, body parts and moving elements relative to the external environment.
3. Tap- a constructive type of pipeline industrial fittings, the regulating or shut-off body of which has the shape of a body of revolution (or part of it), rotates around its axis and is located arbitrarily with respect to the direction of flow.
4. Gate- a constructive type of pipeline fittings, the regulating or shut-off body of which has the shape of a disk and rotates around a non-own axis.

Conditional pressure of the working medium

• Vacuum fittings (working medium pressure below 0.1 MPa abs.)
• Low pressure (0-1.5 MPa)
• Medium pressure valves (1.5-10 MPa)
• High pressure (10-80 MPa)
• Pipe fittings of ultrahigh pressure (80 and more MPas)

Method of connection to the pipeline

Depending on the method of fastening to the pipeline, the following types of industrial fittings are distinguished: coupling, nipple, fittings for welding, coupling, pin, flange, fitting.

1. Accession coupling industrial fittings to the pipeline is carried out using couplings having an internal thread.
2. Accession nipple fittings to the pipeline is made using a nipple.
3. Accession pipeline fittings intended for welding carried out by welding. This method of connecting fittings to the pipeline has both advantages and obvious disadvantages. In particular, high-quality welding of fittings guarantees absolute tightness of the connection, does not require maintenance (tightening of flange connections), however, it can cause certain problems during repair work, work on replacing fittings.
4. Fastening tie rod to the pipeline is made using nuts and studs.
5. .Connection flange fittings to the pipeline is made using flanges. This fastening method also has advantages (possibility of multiple installation and dismantling of fittings, high strength, possibility of operation under a wide range of operating pressures and passages) and disadvantages (possible weakening of fastening, loss of tightness of the connection, large weight and dimensions).
6. Mounting pin fittings to the pipeline is made on an external thread with a collar for sealing.
7. Choke fittings attached to the pipeline with fittings.

Sealing method

Depending on the method of sealing, the following types of industrial pipeline fittings are distinguished: membrane, bellows, stuffing box.

1. With help membrane fittings the sealing of the housing elements, movable connecting elements relative to the external environment is carried out. In addition, membrane fittings allow sealing in the valve.
2. Gland fittings allows to ensure the sealing of the spindle or rod relative to the external environment: the sealing of the connection is carried out with the help of stuffing box packing, which is in direct contact with the movable spindle or rod.
3. Bellows fittings used to seal moving parts (spindle, rod) relative to the external environment. As a seal, a bellows is used, which is a power or sensitive element of the structure.

Control method

Depending on the control method, the following types of industrial pipeline valves are distinguished: actuated valves, valves with remote, automatic and remote control.

1. main feature fittings designed for remote control, - the absence of a governing body. The connection with the control body is made with the help of transitional elements (columns, rods, etc.).
2. Control actuated pipeline fittings by means of a drive (remotely or directly).
3. Control industrial pipeline fittings designed for automatic control, carried out without the participation of the operator. Automatic control is provided due to the direct impact of the working environment on the power or sensing element, or by means of signals coming to the drive from instruments and devices of the automatic control system.
4. Control manual valve performed by an operator.

According to GOST 9544-93, for all types of valves (with the exception of special valves and valves with an electric drive), the following classes of joint tightness are established at a conditional pressure of 0.1 MPa or more.

Table of the minimum duration of hydraulic tests of the blockage:

Table of the dependence of the values ​​of media and pressures for hydraulic tests on nominal (conditional) pressures and diameters:

The choice of medium for hydraulic testing is carried out depending on the functional purpose of pipeline fittings and compliance with the requirements of GOST (water - GOST P 51232-98, air - class 0 GOST 17433-80). When conducting hydraulic tests, the temperature of the test medium must be less than 5 ° C, but not more than 40 ° C. Permissible error in measuring leaks: ± 0.01 cm³ / min. for leaks less than 0.1 cm³/min. and ±5% for leaks greater than 0.1 cm³/min.

Reinforcement symbol according to the classification of TsKBA (table-figure)

Classification of pipeline industrial fittings (classification of TsKBA) is made on the basis of accepted symbols, consisting of letters and numbers. The first two digits in the product marking indicate the type of industrial fittings (see Table 1). The letter (or combination of letters) after the first two digits indicates what material the body of the product is made of (see Table 2). Letters (or a combination of letters) are followed by one or two digits indicating the model number. If three digits are indicated after the letter designation, then the first one is the type of drive (see table 3), and the next two digits are the model number. The last letters in the marking indicate the material from which the sealing surfaces are made (see Table 4) or indicate the method by which the internal coating of the product body was carried out (see Table 5). Reinforcement made without welded or plug-in rings is designated "bk".

Table 1

table 2

Table 3

Table 4

Table 5

In parallel with the classification system of TsKBA, a system of codes obtained as a result of abbreviation of the factory name of products is often used to classify industrial fittings. For example, to designate a ball valve with a nominal pressure of 16 kg / cm³ and a nominal bore of 15 mm, the designation KSh-16/15 is used. To designate some types of reinforcing structures, only the number of the drawing documentation is used, according to which they were manufactured. Often, when classifying products, a letter indicating the name of the manufacturing plant is indicated.

To classify valves intended for operation in such industries as oil refining and oil production, a symbol of numbers and letters is also used. If the letters indicate the type of reinforcement, then the digital value indicates the operational parameters of the product. For example, a cast wedge gate valve of the 2nd modification, having a nominal pressure of 16 kg / cm³ and a nominal bore of 200 mm, is designated as ZKL2-200-16.

It is customary to use abbreviations to designate the working environment in catalogs of industrial pipeline fittings (see Table 6).

Table 6

Selection of valves for gas distribution systems

When choosing pipeline valves intended for operation in gas distribution systems, it is necessary to be guided by the following provisions and regulatory documents: PB 12-529-03, SNiP 42-01-2002 and SP 42-101-2003. In gas supply networks with pressure up to 1.6 MPa, it is recommended (depending on operating conditions) to use the types of pipeline fittings indicated in the table:

When installing pipeline fittings on external gas pipelines in areas with cold climatic conditions, it is necessary to use products in the climatic version UHL1, UHL2, HL1, HL2. When carrying out installation work of pipeline fittings on internal gas pipelines in heated premises, it is necessary to choose products in the climatic version U1, U2, U3, U5, UHL4, UHL5, HL5, and for unheated premises it is recommended to use UHL3, HL3 (according to GOST 15150-69).

When installing pipeline fittings on internal (in unheated premises) and external gas pipelines in areas with a moderately cold climate, it is necessary to choose products in the climatic version U1, U2, U3, UHL1, UHL2, UHL3 (according to GOST 15150-69).

It is recommended to choose pipeline fittings for external and internal gas pipelines in unheated premises, taking into account the operating pressure in the system, climatic conditions, body material, based on the data given in the table:

Carbon steel

* Manufacture of body parts of fittings should be carried out from the following materials: stamped and forged products - wrought alloy grade D-16 (alloy D-1 can be used), cast products - guaranteed quality with mechanical properties not lower than grade AK - 7ch (AL-9) (according to GOST 1583-93).

It is customary to choose the temperature of the coldest week with a probability of 0.92 (according to SNiP 23-01-99) as the design temperature for the operation of the fittings and the temperature of the working medium.

The hermetic density of the gate of taps and gate valves with a conditional (nominal) passage of up to 80 mm must correspond to class B. If there is a conditional passage of more than 80 mm - class C (according to GOST 9544-93).

The hermetic tightness of the gate of tension cone valves with a nominal pressure of up to 0.1 MPa, which are not subject to GOST 9544-93, must comply with the class standards for a working pressure of 0.1 MPa (according to GOST 9544-93).

The hermetic tightness of the gate of valves, which are installed on LPG liquid phase gas pipelines, must comply with class A. When installing valve congestion on other types of gas pipelines - compliance with class B (according to GOST 9544-93).

Pipeline industrial fittings involved in gas supply systems must have a passport in which it is recorded that the working medium for this product is liquefied or natural gas.

In a number of cases (subject to compliance with the requirements for the tightness of products; with the resistance of the sealing materials of the valve and body connectors to the transported gas), the operation of valves designed for natural or liquefied gas is possible for steam, water and ammonia.

The choice of working and conditional pressure of shut-off valves is carried out depending on the parameters of the working pressure in the system and must correspond to the data indicated in the following table:

According to the requirements of GOST 4666-75, all types of pipeline valves must be marked and have a distinctive color. The marking is applied to the body of the product and must contain the manufacturer's trademark, operating or nominal pressure, nominal bore and, if necessary, an indicator of the direction of the flow of the working medium. Coloring of a cover and the body of stop valves is carried out depending on material.

The electric drive of shut-off valves must be made in an explosion-proof design.

The main characteristic of the pipeline is the diameter and wall thickness of the pipes from which it is made. Each pipe has two diameters: inner D in and outer D n. Between the inner and outer diameters of the pipes there is the following relationship:
,
where S is the pipe wall thickness.

When the wall thickness of the pipe changes, the inner diameter of the pipe changes, while the outer diameter of the pipe remains constant, since its change inevitably causes a change in the dimensions of the attached fittings and fittings.

In order to preserve for all elements of the pipeline (pipes, fittings and fittings) the value of the flow area, which provides the design conditions for the passage of liquid, steam or gas, the concept conditional pass. The nominal diameter of pipes, fittings and fittings is understood as the average inner diameter of pipes (in the light), which corresponds to one or more outer diameters of pipes. The nominal bore is denoted by the letters DN with the addition of the nominal bore in millimeters: for example, a nominal bore with a diameter of 150 mm is indicated DN 150. The true inner diameter of pipes is usually not equal to and does not correspond (with rare exceptions) to the nominal diameter. So, for example, for pipes with an outer diameter of 159 mm and a wall thickness of 8 mm, the true inner diameter is 143 mm, and for a wall thickness of 5 mm - 149 mm, however, in both cases, the conditional bore is assumed to be 150 mm.

The nominal diameters of fittings, fittings, as well as all parts of the technological equipment of devices to which pipes or fittings are attached, are established by GOST 28338-89 “Pipeline connections and fittings. Conditional passages (nominal dimensions). Rows. These quantities have the following range of meanings:

The wall thickness of pipes and pipeline parts is selected depending on the highest pressure of the medium (gas or liquid) transported through the pipeline, on its temperature and on the mechanical properties of the pipe metal.

As is known, the mechanical strength of the metal of pipes, fittings and fittings changes with increasing temperature. To link the pressure and temperature of the medium flowing through the pipeline, the concept of "conditional pressure" was introduced, which is denoted by the letters P y.

According to GOST 356-80 “Conditional test and working pressures. Rows. Conditional pressure (P y) should be understood as the highest excess pressure at an ambient temperature of 293 K (20 ° C), at which long-term operation of fittings and pipeline parts with specified dimensions, justified by strength calculations with selected materials and their strength characteristics corresponding to temperature 293 K (20°C).

Test pressure (P pr) should be understood as excess pressure at which a hydraulic test of fittings and pipeline parts for strength and density with water at a temperature of at least 278 K (5 ° C) and not more than 343 K (70 ° C) should be carried out, if the regulatory and technical documentation does not indicate the specific value of this temperature. The maximum deviation of the test pressure value should not exceed ±5%.

The working pressure (P p) should be understood as the highest overpressure at which the specified mode of operation of valves and pipeline parts is ensured.

The values ​​of conditional pressures of fittings and pipeline parts must correspond to the following series: 0.10 (1.0); 0.16 (1.6); 0.25 (2.5); 0.40 (4.0); 0.63 (6.3); 1.00 (10); 1.60(16); 2.50 (25); 4.00 (40); 6.30 (63); 10.00 (100); 12.50(125); 16.00 (160); 20.00 (200); 25.00 (250); 32.00 (320); 40.00 (400); 50.00 (500); 63.00 (630); 80.00 (800); 100.00 (1000); 160.00 (1600); 250.00 (2500) MPa (kgf / cm 2).

For fittings and pipeline parts, the production of which was mastered before the entry into force of GOST 356-80, conditional pressures of 0.6 (6) are allowed; 6.4 (64) and 8.0 (80) MPa (kgf / cm 2).

The production of hydraulic tests with test pressure is necessary to check the reliability of the pipeline under operating conditions, therefore, the test pressure is always 1.25-1.5 times greater than the working and conditional pressure, unless the regulatory documentation establishes even higher test pressure values.

VESSELS AND DEVICES

Norms and methods for calculating strength

Vessels and Apparatus.

Norms and methods of strength calculation

MKS 71.120.01

Date of introduction 01.01.90

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of Chemical and Petroleum Engineering

2. APPROVED AND INTRODUCED BY Decree of the USSR State Committee for Standards dated 18.05.89 No. 1264

3. REPLACE GOST 14249-80

4. The standard fully complies with ST SEV 596-86, ST SEV 597-77, ST SEV 1039-78, ST SEV 1040-88, ST SEV 1041-88

5. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

6. EDITION (April 2003) as amended (IUS 2-97)

This standard establishes the norms and methods for calculating the strength of cylindrical shells, conical elements, bottoms and covers of vessels and apparatus made of carbon and alloy steels used in the chemical, oil refining and related industries, operating under conditions of single and repeated static loads under internal overpressure, vacuum or external overpressure and under the action of axial and transverse forces and bending moments, and also sets the values ​​​​of allowable stresses, the modulus of longitudinal elasticity and the strength factors of welds. The norms and methods for calculating strength are applicable subject to the "Rules for the Design and Safe Operation of Pressure Vessels" approved by the USSR Gosgortekhnadzor, and provided that deviations from the geometric shape and inaccuracies in the manufacture of the calculated elements of vessels and apparatus do not exceed the tolerances established by the regulatory technical documentation.

GENERAL REQUIREMENTS

Design temperature

1.1.1. The design temperature is used to determine the physical and mechanical characteristics of the material and the allowable stresses.

1.1.2. The design temperature is determined on the basis of thermal engineering calculations or test results.

The maximum value of the wall temperature is taken as the design temperature of the wall of the vessel or apparatus. At temperatures below 20°C, the temperature of 20°C is taken as the design temperature when determining the allowable stresses.

1.1.3. If it is not possible to carry out thermal calculations or measurements and if during operation the wall temperature rises to the temperature of the medium in contact with the wall, then the design temperature should be taken as the highest temperature of the medium, but not lower than 20°C.

When heated by an open flame, exhaust gases or electric heaters, the design temperature is assumed to be equal to the ambient temperature increased by 20 ° C for closed heating and by 50 ° C for direct heating, unless more accurate data are available.

Working, design and test pressure

1.2.1. The working pressure for a vessel and apparatus should be understood as the maximum internal overpressure or external pressure that occurs during the normal course of the working process, without taking into account the hydrostatic pressure of the medium and without taking into account the permissible short-term pressure increase during the operation of the safety valve or other safety devices.

1.2.2. Under the design pressure under operating conditions for the elements of vessels and apparatuses, one should understand the pressure at which their strength calculation is carried out.

The design pressure for the elements of the vessel or apparatus is usually assumed to be equal to the working pressure or higher.

When the pressure in the vessel or apparatus increases by more than 10% during the operation of the safety devices, compared to the working one, the elements of the apparatus must be designed for a pressure equal to 90% of the pressure when the valve or safety device is fully opened.

For elements separating spaces with different pressures (for example, in apparatuses with heating jackets), either each pressure separately or the pressure that requires a greater wall thickness of the calculated element should be taken as the design pressure. If the simultaneous action of pressures is ensured, then it is allowed to carry out the calculated pressure difference. The pressure difference is taken as design pressure also for elements that separate spaces with internal overpressure from spaces with an absolute pressure less than atmospheric pressure. If there are no exact data on the difference between absolute pressure and atmospheric pressure, then the absolute pressure is assumed to be zero.

Main parameters

Under the term "pipe fittings" understand a device installed on pipelines, units, vessels and designed to control (shutdown, distribution, regulation, discharge, mixing, phase separation) flows of working media (liquid, gaseous, gas-liquid, powder, suspension, etc.) by changing the area of ​​the passage sections.

Pipe fittings are characterized by two main parameters:

• conditional passage (nominal size),
• conditional (nominal) pressure.

Nominal size (nominal size) (D y or DN) is a parameter used for piping systems as a characteristic of connected parts, such as piping connections, fittings and fittings. The nominal diameter (nominal size) is approximately equal to the inner diameter of the pipeline to be connected, expressed in millimeters. The values ​​​​of conditional passes must correspond to the numbers of the parametric series established by GOST 28338-89 (a total of 50 indicators from 2.5 to 4000).

The conditional passage or nominal size is indicated using the designation Dy or DN and a numerical value selected from a range. For example, nominal bore (nominal size) 200 should be designated: Dy 200 or DN 200.

Conditional (nominal) pressure (P y or PN)- the highest excess working pressure at a working medium temperature of 20°C, at which the specified service life of pipeline and valve connections of certain dimensions is ensured, justified by the strength calculation for the selected materials and their strength characteristics at a temperature of 20°C.

GOST 26349-84 defines a parametric series of nominal pressures, consisting of 27 parameters from 0.1 to 1000 kgf / cm 2

Conditional (nominal) pressures less than 0.1 kgf / cm 2 are determined according to GOST 8032-56.

In contrast to conditional pressure, test and working pressures are distinguished.

Trial pressure (P pr)- this is the excess pressure at which a hydraulic test of fittings and pipeline parts for strength and density with water at a temperature of at least 5 ° C and not more than 70 ° C should be carried out, if the specific value of this temperature is not indicated in the regulatory and technical documentation.

Working pressure (P)- this is the highest overpressure at which the specified mode of operation of fittings and pipeline parts is ensured, that is, at a given operating temperature. The temperature of the medium should be taken equal to the temperature at which the product is operated for a long time without taking into account short-term deviations allowed by the relevant regulatory and technical documentation.

The working pressures are equal to conventional ones for carbon steel fittings at an ambient temperature from -20 to +200°С, for gray cast iron fittings from -15 to +120°С, for malleable iron fittings from -30 to +120°С, for fittings made of brass and bronze from -30 to +120°С, for titanium alloys from -40 to +50°С. With an increase in the working temperature of the medium, the permissible working pressure is reduced depending on the material of the valve body parts. Armature is made from carbon steel for operating temperatures up to 445°C, from gray cast iron - up to 300°C, from ductile iron - up to 400°C, from bronze and brass - up to 250°C, from titanium - up to 350°C.

The value of the test pressure for fittings and pipeline parts designed for a working pressure of less than 1 kgf / cm 2 and for operation in vacuum is taken equal to:

• at an operating pressure of less than 1 kgf / cm 2 P pr \u003d P + 1 kgf / cm 2
• in vacuum P pr \u003d 1.5 kgf / cm 2

Examples of designations according to GOST 356-80

• conditional pressure 40 kgf / cm 2 - R y 40 or PN 40
• test pressure 60 kgf / cm 2 - R pr 60
• operating pressure 250 kgf / cm 2 at a temperature of 530 ° C - P 250 t 530

General basic terms and concepts

Along with the main concepts listed above, the following terms are most often used in valve building, reflecting specific elements, objects and parameters of manufactured products.

• Reinforcement type- classification unit, characterized by the interaction of the movable element of the valve (closing body) with the flow of the working medium and determines the main design features of pipeline valves. For example gate valve, faucet, valve, etc.
• Reinforcement type- classification unit characterizing the functional value of pipeline fittings. For example, shut-off, regulating, etc.
• Valve size- the design of pipeline fittings, regulated by the conditional passage and conditional pressure and having the designation of the group main design document (the main version of the product).
• Valve design- the design of one of the types of pipeline valves, regulated, in addition to the nominal diameter and nominal pressure, by variable data: the material of the main parts, connection to the pipeline, type of control, etc., about which information is contained in one group or basic design document. The execution corresponds to a specific OKP code.
• Structural range- pipeline fittings of the same design, differing only in conditional passages.
• parametric series- designs of pipeline fittings of various conditions of passages, having the same nominal parameters.
• Ratings- pressure and temperature of the working medium, specified to take into account deviations in tolerances.
• Workspace- liquid, gas, slurry or mixtures thereof and other substances, for the control of which (shutdown, distribution, regulation, discharge, mixing, phase separation), pipeline valves are intended.
• External (environment) environment- atmospheric air, gas, liquid or other substances surrounding pipeline fittings.
• Control environment- liquid, gas or other substances used as a working fluid in valve actuators, that is, creating a shifting force on a locking or regulating element.
• Team environment- liquid, gas or other substances used to transmit command signals to the valve actuator.
• Absolute pressure (P abs)- pressure measured taking into account atmospheric pressure.
• Overpressure (P)- pressure measured without taking into account the action of atmospheric pressure - atmospheric pressure (P, a) is taken as the reference zero, P \u003d P abs - P a. When P abs > P, and the pressure P is also called gauge pressure.
• Vacuum (W)- positive difference between atmospheric pressure and absolute pressure - W = P, a - P abs (when P, a > P abs). In engineering calculations, P is usually taken, a \u003d 1 kgf / cm2.
• Working temperature (T p, °С)- the maximum temperature of the working medium, acting during the normal course of the technological process, without taking into account random short-term increases.
• Construction length of fittings (L)- the linear size of the reinforcement between the outer end planes of its connecting parts (flanges, couplings, fittings, nipples, welding pipes).
• Structural height of reinforcement (H)- distance from the axis of the valve body bushings to the highest point of the structure (spindle or drive) with the product open.
• Hydraulic resistance coefficient- the ratio of the lost pressure to the velocity (dynamic) pressure in the agreed (accepted) flow section.
• v Flow section - the area formed by the mutual arrangement of the movable and fixed elements of the shutter.
• Leak (leak)- the volume or weight of the working medium passing through the gate closed with nominal pressure per unit time at given parameters (pressure, temperature, density).
• tightness- the property of the connection (detachable, one-piece, with movable or fixed contact) to prevent leakage.
  The tightness class for stop valves is indicated in the technical specifications for a specific type of valve. The leakage values ​​correspond to the case of outflow into the atmosphere. When determining leaks, the nominal diameter is taken in millimeters.
• impenetrability- a property of the material of the part, characterized by the absence of cracks, friability, gas inclusions through which the working medium can penetrate.
• Reliability- the property of pipeline valves to perform the specified functions, maintaining the established values ​​of operational indicators over time within the required limits and taking into account the mode of operation, the conditions for its use and maintenance, as well as taking into account repairs, storage and transportation. The property is complex, it includes such requirements as reliability, durability, etc. These requirements can be considered separately or included in the form of a certain combination in the assessment of the reliability of the valve or its individual components and parts.
• Reliability- a single indicator of the reliability of pipeline valves, which characterizes the ability of valves to maintain operability continuously for some time or some operating time.
• Durability- a single indicator of reliability that characterizes the ability of the valve to remain operational until the limit state occurs with the necessary interruptions, determined by the established system of maintenance and repairs. An indicator of durability is the service life or resource.
• performance- the state in which pipeline fittings can perform the specified functions.
• Operating time- the duration of operation of pipeline valves in time or in quantitative terms in the form of “closed-open” operation cycles. The operating time can continue continuously or intermittently, in the latter case, the total operating time is taken into account.
• Cycle- movement of the locking element from its original position ("closed", "open") to the opposite and vice versa, associated with the performance of the main function of this type of reinforcement.
• Life time- calendar duration of valve operation from its beginning or renewal after an average or major overhaul until the limit state of the valve.
• Resource- valve operating time from the start of operation or its restoration after a medium or major overhaul until the onset of the limit state specified by the regulatory and technical documentation.
• limit state- the state of pipeline fittings, in which it performs its functions, but cannot be used for further operation, which must be terminated due to an unrecoverable violation of safety requirements. The limiting state can occur either as a result of the departure of the specified parameters beyond the established limits, or due to the need for medium or major repairs, as well as due to a decrease in the efficiency of valve operation.
• Long lasting strength- the ability of the material of the part to maintain strength under prolonged stress in it (especially important at high temperatures).
• Cycle strength- the ability of the material of the part to maintain strength with the periodic occurrence of stresses in it.
• thermal shock- sudden action on the metal of high temperature (with a sudden entry into the fittings of a highly heated liquid, for example, a metal coolant).
• Thermal cycle strength- the property of the material to maintain strength when exposed to thermal shocks.
• Flammable, explosive or toxic environment- a gas or liquid capable of igniting, exploding or having a harmful effect on humans or animals.

Conventions

The use of a system of symbols for fittings allows you to briefly record some of the main technical parameters of the product. The use of the index system provides the possibility of the correct selection of reinforcement, its intended use and increases the possibility of control of reinforcement during installation. The TsKBA (Central Design Bureau of Valve Building) system, which contains a digital and alphabetic code for the main valve data, has received the greatest distribution. According to the TsKBA system, the product index includes five elements arranged in series (in the absence of a drive, the product index consists of four elements).

The first two digits indicate the type of valve (table 1), the letters after them indicate the body material (table 2), one or two digits after the letters indicate the model number (design features of the product), if there are three digits: the first of them indicates the type of actuator (table 3) , and the next two are the model number; the last letters - the material of the sealing surfaces (table 4) or the method of applying the internal coating of the body (table 5) .

In some cases, after the letters indicating the material of the sealing surfaces, a number is added that indicates the version of the product or its manufacture from another material. A product without insert or welded rings, that is, with sealing surfaces made directly on the body or valve, is indicated by the letters "bk" (without rings).

For example:

• 15s922nzh Flanged steel shut-off valve with electric actuator
• 15 - according to the table 1 - shut-off valve
• c - according to table 2 - from carbon steel
• 9 - according to table 3 - with electric drive
• 22 - model number
• nzh - according to table 4 - sealing surfaces welded with corrosion-resistant steel

For valves with electric actuators in an explosion-proof version, the letter B is added at the end of the symbol (for example, 30ch906brB), and in a tropical version, the letter T (for example, 30ch906brT). The letters B and T are indicated when ordering.

Along with the TsKBA system, they use a code obtained by abbreviating the name of the product, for example, KTS - a three-way steel crane, etc. Individual structures are designated only by the number of the drawing according to which they are manufactured. Sometimes a letter is entered into the designation indicating the valve manufacturer.

The symbolic designation of valves intended for the oil refining and oil production industry consists of letters and numbers. The letters indicate the type of fittings, the numbers behind the letters - the parameters of the product, for example, ZKL-200-16 - a cast wedge valve with a nominal bore of 200 mm, for a nominal pressure of 16 kgf / cm 2 or YuL-160 - a feed valve for a nominal pressure of 160 kgf / cm 2. Products that do not have a symbol are indicated by a drawing number.

At present, many new symbols of reinforcement have appeared that are not amenable to any systematization. These designations are given in the handbook as they were accepted by the manufacturer (or developer)

Tables!

Rebar classification

1. By scope:

• General purpose industrial pipeline valves- used in various sectors of the national economy. It is mass-produced in large quantities and is intended for media with frequently used pressures and temperatures. These fittings are equipped with water pipes, steam pipelines, city gas pipelines, heating systems, etc.
• Industrial valves for special working conditions- is intended for operation at relatively high pressures and temperatures, at low temperatures, in corrosive, toxic, radioactive, viscous, abrasive or friable media. These fittings include: power fittings of high energy parameters, cryogenic, corrosion-resistant, fountain fittings, heated fittings, fittings for abrasive slurries and for bulk materials.
• Special fittings designed and manufactured according to individual orders based on special technical requirements. Often such fittings are manufactured, for example, for experimental or unique industrial installations, including nuclear power plants.
• Marine fittings is produced for operation in specific operating conditions on river and sea vessels, taking into account increased requirements for minimum weight, vibration resistance, increased reliability, special control and operating conditions.
• Plumbing fittings various household appliances are equipped: gas stoves, bathroom units, kitchen sinks, etc. These fittings are manufactured in large quantities at specialized enterprises, have small passage diameters and are mostly controlled manually, with the exception of pressure regulators and safety valves for gas.

2. By functional purpose (type):

• Shut-off valves designed to completely shut off the flow of the working medium in the pipeline and start the medium, depending on the requirements of the technological process ("open-closed" cycle). The main purpose of shut-off valves is to shut off the flow of the working medium through the pipeline and re-start the medium, depending on the requirements of the technological process served by this pipeline, ensuring tightness both in the gate and in relation to the external environment. Shut-off valves in terms of the number of units used make up 80% of all valves.
• Control valves is designed to regulate the parameters of the working medium by changing its flow rate. It includes control valves, pressure regulators, liquid level regulators, throttling fittings, etc.
• Distribution-mixing (three-way or multi-way) fittings is designed to distribute the working medium in certain directions or to mix medium flows (for example, cold and hot water). This includes control valves and faucets.
• Safety fittings is designed for automatic protection of equipment and pipelines from inadmissible pressure by dumping excess working medium. This includes safety valves, impulse safety devices, diaphragm rupture devices, bypass valves.
• Protective fittings is designed to automatically protect equipment and pipelines from unacceptable or envisaged by the technological process changes in the parameters or direction of the flow of the working medium and to turn off the flow without ejection of the working medium from the technological system. This includes non-return valves, shut-off valves.
• Control armature used to check the presence and determine the level of liquid in boilers, tanks and vessels, as well as to connect instrumentation in hydraulic and pneumatic systems. This includes pilot and bleed valves, level indicators, cocks and valves for pressure gauges.
• Phase dividing fittings is designed for automatic separation of working environments depending on their phase and state. These include steam traps, air vents and oil separators.

3. By constructive types:

• gate valve- pipeline fittings, in which the locking element moves back and forth perpendicular to the direction of the flow of the working medium. It is mainly used as shut-off valves: the locking element is in the extreme positions "open" and "closed". A variation of this type of fittings are pinch valves, in which the medium flow is shut off by a shut-off device that compresses an elastic hose, inside which the transported working medium passes.
• Valve- pipeline valves, in which the locking or regulating element moves back and forth parallel to the axis of the flow of the working medium in the saddle of the valve body. A valve in which the closing element is moved by means of a screw pair and is manually controlled is called a valve. This name is now obsolete. A variation of this type of fitting is a diaphragm valve, in which a diaphragm is used as a shut-off element. The membrane is fixed along the outer perimeter between the body and the cover, it performs the function of sealing body parts and moving elements relative to the external environment, as well as the function of sealing the shut-off body.
• Tap- pipeline fittings, in which the locking or regulating element has the form of a body of revolution or part thereof; rotates around its axis perpendicular to the direction of the flow of the working medium.
• Shutter (shutter disk)- pipeline fittings in which the locking or regulating element has the form of a disk and rotates around an axis perpendicular to the axis of the pipeline.

4. Depending on the conditional pressure of the working medium:

• vacuum(medium pressure below 1 kgf/cm abs),
• low pressure(from 0 to 16 kgf / cm 2 excess),
• medium pressure(from 16 to 100 kgf / cm 2),
• high pressure(from 100 to 800 kgf / cm 2),
• ultrahigh pressure(from 800 kgf / cm 2).

5. According to the temperature regime:

• cryogenic(operating temperatures below -153°С),
• for refrigeration(operating temperatures from -153 to -70°С),
• for low temperatures(working temperatures from -70 to -30°С),
• for medium temperatures(working temperatures up to +455°С),
• for high temperatures(working temperatures up to +600°С),
• heat-resistant(working temperatures over +600°С).

6. According to the method of connection to the pipeline:

• Coupling fittings. It is connected to the pipeline or container with the help of couplings with internal thread.
• Tsapkovy armature. It is connected to a pipeline or container on an external thread with a shoulder for sealing.
• Weld fittings. Attaches to a pipeline or container by welding. The advantages are complete and reliable tightness of the connection, minimum maintenance (no tightening of the main flange connections is required). The disadvantage is the increased complexity of dismantling and replacing fittings.
• Coupling fittings. The connection of the inlet and outlet pipes with flanges on the pipeline is carried out using studs with nuts passing along the valve body.
• Flanged fittings. Attaches to a pipeline or container using flanges. The advantage is the possibility of multiple mounting and dismounting on the pipeline, good sealing of the joints and the convenience of tightening them, greater strength and applicability for a wide range of pressures and passages. Disadvantages - the possibility of loosening and loss of tightness over time, large overall dimensions and weight.
• Fittings fitting (nipple). It is connected to a pipeline or container with a fitting (nipple).

7. According to the method of sealing (sealing) relative to the external environment:

• Valves are stuffing box. The sealing of the rod or spindle relative to the external environment is provided by an elastic element that is in contact with the movable rod (spindle) under a load that excludes leakage of the working medium.
• Membrane fittings. A membrane is used as a sensitive element. It can perform the functions of sealing body parts, moving elements relative to the external environment, as well as sealing in the gate.
• Bellows armature. To seal moving parts (rod, spindle) relative to the external environment, a bellows is used, which is also a sensitive or power element of the structure.
• Hose fittings. An elastic hose ensures the tightness of the entire internal cavity of the fitting in relation to the external environment.

8. According to the method of control:

• Fittings for remote control. It does not have a direct control, but is connected to it using columns, rods and other adapters.
• Drive armature. The control is carried out by means of a drive (directly or remotely).
• Valves with automatic control. The shutter is controlled without the participation of the operator under the direct influence of the working medium on the shutter or on the sensitive element, either by acting on the valve actuator of the control medium, or by a command signal coming to the valve actuator from the ACS devices.
• Valves with manual control. The control is carried out by the operator manually remotely or directly.