Has an internal threaded connection. Thanks to this threaded connection, the coupling valve has a shorter overall length and weight.
Diagram of a coupling ball valve
The advantage of the crane is that additional fasteners are not needed for a reliable connection. It is also indispensable in those sections of the pipeline where there is not enough space to work with a wrench.
Flange ball valve
Attaches to flanges. Connection is ensured by two flanges, an O-ring, connecting bolts and nuts.
Diagram of a flanged ball valve
The cranes are easy to install and maintain; they can be mounted and dismantled many times, while flanged valves are large in size and weight. Typically used on pipelines where it is required frequent installation and dismantling of cranes.
Ball valve
This is a valve with an external thread, to which a nipple with a union nut is attached. The design ensures the small size and weight of the product, while this crane is easy to maintain and install.
Diagram of a ball valve
They are easy to install and maintain, they can be mounted and dismantled many times. Unlike flanged valves, it takes less space and can be installed in hard-to-reach places.
Welded ball valve
Has welded ends. Such taps are lightweight, hermetically attached to the pipe, but are difficult to maintain: dismantling and replacing them is quite labor-intensive.
Diagram of a welded ball valve
Intended for high pressure working environment, therefore they have high tightness of the overlap and strength of the connection.
The word "flange" came into Russian from German language together with the flange itself, and was not assigned on the basis of some analogies. In German, the noun Flansch means exactly the same thing as its derivative Russian word“flange”, ─ a flat metal plate at the end of a pipe with holes for threaded fasteners (bolts or studs with nuts). It is more common when this plate is round, but the shape of the flanges is not limited to one disk. For example, square and triangular flanges are used. But round ones are easier to make, so the use of rectangular or triangular flanges can be justified for really good reasons.
The material, types and design features of the flanges are determined by the nominal diameter, pressure of the working medium and a number of other factors.
For the manufacture of pipeline valve flanges, gray and ductile cast iron is used, different varieties become.
Ductile iron flanges are designed to withstand higher pressures and a wider temperature range than flanges made from gray cast iron. Cast steel flanges are even more resistant to these factors. Welded steel, just as easy to carry high temperatures, are inferior to cast flanges in the maximum permissible pressure.
Design features of flanges may include the presence of projections, chamfers, spikes, annular recesses, etc.
The prevalence of flanged connections for pipeline fittings is due to their many inherent advantages. The most obvious of them is the possibility of repeated installation and dismantling. The temptation to add the adjective “easy” to the noun “installation” is somewhat reduced if we remember how many bolts will need to be unscrewed and tightened when disassembling and joining flanges of large diameters (flange connections are usually used for pipe diameters of 50 mm or more). Although in this case the labor intensity installation work will not go beyond the bounds of reason.
Flange connections are durable and reliable, which allows them to be used to complete pipeline systems operating under high pressure. Subject to certain conditions, flange connections provide very good tightness. To do this, the flanges being joined must have similar flanges that do not go beyond permissible error, connecting dimensions. Another condition is mandatory periodic tightening of joints, which allows maintaining the “grip” of bolted joints at the proper level. This is especially important when they are constantly exposed to mechanical vibrations or there are significant fluctuations in temperature and humidity environment. And the larger the diameter of the pipeline, the more relevant this is, because as it increases, the force on the flanges increases. The tightness of flange connections largely depends on the sealing ability of the gaskets installed between the flanges.
Deformations cannot be discounted. Moreover, flanges made of different materials, are subject to them to different degrees, so the material from which it is made is the most important parameter flange. Thus, ductile steel flanges are deformed more easily than those made of cast iron, which is more brittle but holds its shape much better.
The disadvantages of flanged fittings are a continuation of its advantages. High strength results in significant overall dimensions and weight, which, in turn, mean increased metal consumption (in the manufacture of large flanges it is necessary to use thick a metal sheet or round profiles large diameter) and labor intensity of production.
Weld fittings
Welding of reinforcement is resorted to when the reliability and tightness of other types of connections is considered unsatisfactory. Welding is especially in demand when constructing pipeline systems in which the working environment is toxic, poisonous or radioactive liquids and gases. In this case, a welded connection, which, if properly executed, provides 100 percent tightness, may be the optimal, and often the only acceptable solution. It is only important that such a section of the system does not require frequent dismantling of equipment, the implementation of which will each time lead to complete destruction welded joints.
Thanks to welding, which combines fragments of a pipeline system into a single whole, it is possible to ensure harmony, or, in technical terms, structural compliance between all its elements - pipes and pipeline fittings. The main thing is that because of the differences mechanical properties welded joint and other components of the pipeline system, it did not become its weak link.
The connecting ends of the reinforcement are prepared for welding by leveling and grinding the surface of the welded fragments, removing the required chamfers.
Welded joints can be made in socket and butt. In the first case, the welding seam is located on outside pipes. This option is usually used for steel reinforcement of relatively small diameter, installed in pipelines operating at high pressure and temperature of the working environment.
In the second case, the connection can be supplemented with a backing ring, which prevents distortion of the parts being connected. It is precisely these connections, characterized by reliability and absolute tightness, that are used when installing pipeline systems of hazardous production facilities, for example, power units of nuclear power plants.
Important advantages of welded connections, especially compared to flanged ones, are minimum weight, compactness and space saving.
Coupling fittings
One of the most common in technology is the coupling connection of reinforcement.
It is used for various types valves of small and medium diameter, operating at low and medium pressures, the body of which is made of cast iron or alloys of non-ferrous metals. If the pressure is high, then it is preferable to use pin fittings.
In the connecting pipes of the coupling fittings, the thread is with inside. As a rule, this is a pipe thread ─ inch thread with small steps. It is formed different ways─ knurling, cutting, stamping. It is important that with a fine thread pitch, the height of the teeth does not depend on the diameter of the pipeline.
On the outside, the connecting ends are designed in the form of a hexagon to make it convenient to use the key.
The word “coupling” came into Russian from German, and possibly from Dutch, where mouw means sleeve. The coupling, like the valve, is an example of how tailoring and the production of pipeline fittings each use, in their own special terminology, the same sound, but carrying different semantic load words. In engineering, a coupling is not a sleeve, but a short metal tube that provides connections to the cylindrical parts of machines.
The fine thread of the coupling connection plus the use of special viscous lubricants, flax strands or fluoroplastic sealing material (FUM tape) guarantee its high tightness. The coupling connection does not require the use of additional fasteners (for example, bolts or studs, as in flange connection). But one cannot fail to take into account that screwing a coupling onto a thread with a seal requires considerable effort, the greater the larger the diameter of the pipeline.
Union fittings
The German origin of the term “fitting” from the verb stutzen (to trim, cut) even reveals its sound. This is the name given to the muskets used to arm armies up until the 19th century, due to the presence of a rifled barrel. In modern technology, this noun is used to define a short piece of pipe (in other words, a sleeve) with threads on both ends, used to connect pipes and pipeline fittings to units, installations and tanks. In a fitting connection, the connecting end of the valve with external thread is pulled to the pipeline using a union nut. It is used for fittings of small and ultra-small (with a nominal diameter of up to 5.0 mm) diameters. As a rule, this is laboratory or other special fittings. For example, reducers installed on compressed gas cylinders. Using a union connection in pipeline networks Various control and measuring instruments are “implanted”, evaporators, thermostats, and many types of equipment that are part of chemical production lines are installed.
Pin fittings
The term “pin joint” came into widespread use at the end of the 19th century. Its main attributes for pipeline fittings are connecting pipes with external threads and the presence of a collar. The end of the pipeline with the flange is pressed against the end of the fitting pipe using a union nut.
Pin connection is used for high pressure fittings small sizes, in particular, instrumentation devices. It is effective when screwing fittings into the body of vessels, devices, installations or machines. Its tightness is ensured by the presence of gaskets and special lubricants.
An example of a pin connection would be the connection of a fire hose to a fire hydrant.
All threaded connections have such advantages as a minimum number of connecting elements, low metal consumption and, accordingly, low weight, and manufacturability. Efficient installation threaded connections requires a coincidence of internal and external thread, use of soft or viscous materials for compaction. But it should be taken into account that threading reduces the thickness of the pipe wall, so this type of connection is not suitable for thin-walled pipes.
In addition to those listed, there are other ways to connect fittings. Thus, durite compounds can be used in pipeline systems. These are connections through cylindrical couplings consisting of several layers of rubberized fabric (saying in simple words─ fragments of hoses) pushed onto the projections made on the pipes and fixed with metal clamps.
Another way to connect fittings is soldering, which is used for copper pipes with a small diameter. The end of the pipeline, treated with solder, is inserted into the groove made in the pipe.
The functionality, operability and reliability of a pipeline system is determined not only by the parameters of the fittings included in its composition, but also by the quality ofdone reinforcement connection , the selection and implementation of which should always be given special attention.
FEDERAL AGENCY FOR TECHNICAL REGULATION AND METROLOGY
NATIONAL
STANDARD
RUSSIAN
FEDERATION
Pipeline fittings ROTARY ACTUATORS Connection dimensions
Industrial valves - Multi-turn valve actuator attachments
Industrial valves - Part-turn valve actuator attachments
Official publication
Standardinform
Preface
1 DESIGNED Closed joint stock company"Research and production company "Central Design Bureau of Valve Engineering" (JSC "NPF "TsKBA") based on ST TsKBA 062-2009 "Pipeline fittings. Drives rotational movement. Connecting dimensions"
2 8NESEN Technical Committee for Standardization TC 259 “Pipe fittings and bellows”
3 APPROVED AND 8PUT INTO EFFECT by Order of the Federal Agency for Technical Regulation and Metrology dated August 20, 2013 No. 529-Art.
4 This standard takes into account the main regulatory provisions of the following international standards:
ISO 5210 “Pipeline fittings. Connecting dimensions of multi-turn actuators" (ISO 5210 Industrial valves - Multi-turn valve actuator attachments", NEQ):
ISO 5211, “Pipeline fittings. Connecting dimensions of part-turn actuators" (ISO 5211 "Industrial valves - Part-turn valve actuator attachments", NEQ)
5 INTRODUCED FOR THE FIRST TIME
The rules for applying this standard are established by GOST R 1.0 - 2012 (section 8). Information on changes to this standard is published annually (as of January 1 current year) information index “National Standards”, and the official text of changes and amendments is in the monthly information index “National Standards”. In case of revision (replacement) or cancellation of this standard, the corresponding notice will be published in the next issue of the monthly information index “National Standards”. Relevant information, notices and texts are also posted information system common use- on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet (gost.ru).
© Standardinform. 2014
This standard cannot be fully or partially reproduced, replicated or distributed as an official publication without permission from the Federal Agency for Technical Regulation and Metrology
1 ... 1 ... 1 ..2 16
1 area of use............................................... ...........................................
3 Terms and definitions................................................... ....................................
4 Types of connections................................................... ...........................................
5 Designation of connection types.................................................... ...................
Appendix A (mandatory) Connecting dimensions of multi-turn valves
drives for connection types MCH. MK. AC. AK. B. C. D. D...........................
Bibliography
NATIONAL STANDARD OF THE RUSSIAN FEDERATION
Pipeline fittings
ROTARY DRIVES
Connection dimensions
Pipeline valves. Drives of rotary action The connecting dimensions
Date of introduction -2014-02-01
1 area of use
This standard applies to drives and actuators rotary action (hereinafter referred to as actuators) (multi-turn and part-turn, electric, pneumatic, hydraulic, as well as gearboxes) and establishes the types of connections of actuators to pipeline fittings, the connecting dimensions of the actuators and the dimensions of the counter connections of the pipeline fittings controlled by them.
2 Normative references
This standard uses normative references to the following standards:
GOST R 52720-2007 Pipeline fittings. Terms and Definitions
GOST 22042-76 Studs for parts with smooth holes. Accuracy class B. Design and dimensions
3 Terms and definitions
In this standard the following terms are used with their corresponding
definitions:
3.3 multi-turn actuator: A device that imparts a torque to the valve sufficient for at least one revolution. May have the ability to withstand axial load (1].
3.4 part-turn actuator: A device that transmits torque by rotating its output element by one revolution or less, and does not have the ability to withstand an axial load.
3.5 gearbox: A mechanism designed to reduce the torque required to control pipeline fittings)