One of the main issues when choosing pipeline fittings is the type of connection to the system. Usually the existing pipeline system itself dictates to us which type of connection to choose. But if you are faced with the task of designing such a system, then it is important to know all the possible types of connecting pipeline fittings to the system in order to choose the ideal option for your conditions. From our article you will learn about all types, their pros and cons, and you will better understand the types of connections. We'll start with the most popular ones.
Flange connection
This is a connection using two metal plates adjacent to each other. The plates have holes through which bolts or studs pass and are tightened with nuts on the other side, thus pressing the flanges together. For greater reliability and tightness of the connection, protrusions, grooves, etc. are made on the plates, and gaskets are installed between the metal plates. Most often the plates have a rounded shape, but this is not necessary. Occasionally you can find square flanges, rectangular or with three corners, but their production is more expensive. Such forms of flanges are used only when strictly necessary, for example, if space limitations require it. Used on industrial pipelines diameter from DN 50 mm.
The word “flange” comes from the German flansch, which means the same thing as in Russian – a flat metal plate with holes.
Flange connection is one of the most popular connections in pipeline fittings. For the manufacture of flanges, cast iron is most often used - gray or malleable, as well as steel different varieties. Gray cast iron is the most inexpensive solution, but ductile iron can generally withstand a greater range of pressures and temperatures. An even more expensive and durable solution is cast steel flanges. But at the same time, steel is more susceptible to plastic deformation than cast iron, which is brittle but holds its shape well.
Video: installing a flanged LD ball valve on a pipe using
Advantages of flange connection of pipeline fittings
- Strong, reliable connection.
- Withstands high pressure.
- High tightness. But it depends on the seals used.
- Can be mounted and dismantled many times.
Flaws
- Large dimensions flange connection. Large mass.
- High metal consumption and labor-intensive production, and therefore the price.
- The bolts holding the flanges together must be tightened periodically to ensure proper tightness. This is especially important in systems where the pipe is subject to vibration (solved by installation in front of the flange connection) or temperature changes.
Threaded, coupling connection
Also one of the most popular types connections, but for pipeline systems of small diameter (usually up to DN 50) and low pressures (up to 1.6 MPa). Very often found in household pipeline fittings, for example for. Its essence is simple: the pipe has a thread and the fittings have a thread, the latter is screwed onto the former.
You can cut threads on a pipe using special tools, if it does not exist and the equipment has not been installed previously. Threaded pipeline fittings at one end are made in the form of a hexagon for gripping with an adjustable wrench and screwing the fittings onto the pipe thread.
Video: how to cut a thread on a metal pipe and install a threaded ball valve
There are various options execution threaded connections: internal or external thread. The fittings can have on one side internal thread, and on the other - external, or the same type on both sides. There are also different thread standards, for example ISO 228/1 or DIN 2999. You need to take this into account when choosing.
The word “muff” comes from the Dutch word mouw, meaning “sleeve”.
To ensure the tightness of threaded types of connections, additional sealants are used in them - special FUM tapes, flax thread, as well as especially thick lubricants on top of them. All this is applied to the external thread.
Union connection
This is a subtype of threaded connection, which is used on taps of tiny sizes - up to DN 5. When connecting, the threaded fittings are tightened to the threads on the pipe with a union nut. Used for pipes for narrow purposes, such as laboratory pipes. Also used for implanting various measuring devices into pipelines.
Advantages of threaded connections for pipeline fittings
- Low price.
- Not required additional details for installation, such as flange type.
- Easy to install, even easier to replace.
Flaws
- Not suitable for high pressures.
- The larger the diameter, the more effort must be applied to screw the fittings onto the threads with a seal.
Welded connection
If the ends of the pipeline fittings look simply like pipes without any additions, then they are connected to the system by welding. This is the most reliable and hermetically sealed connection, and if done correctly, you can obtain absolute structural compliance of the materials. By welding a valve or faucet to a pipe, you will not have to tighten the bolts, as with flange connection, besides, the cost and weight of such fittings will be significantly less.
This type of connection can often be found on pipeline systems transporting liquids and gases hazardous to health, where the slightest leaks cannot be allowed and absolute tightness is required. For a welded joint, the saying “set it and forget it” is typical. The main thing is to properly connect the pipe to the fittings so that the welding point is not weaker than the pipe wall.
The ends of the pipes must be prepared before welding, and each metal is prepared differently. We offer you a video with the most in a simple way welding
Advantages of a welded connection
- Absolute tightness correct execution welding procedures.
- Low cost of fittings.
- Light weight.
- Small size, the connection does not take up much space.
Flaws
- Qualified personnel are needed, which increases the final cost of installing such fittings.
- A labor-intensive dismantling process, such valves or taps must be installed once and for all.
Clamp quick release connection (Tri-Clamp)
Modern quick release coupling for pipeline fittings, mainly used in Food Industry, pharmacology and other industries where sterility and cleanliness are important. After all, this type of connection allows you to regularly remove, clean, and disinfect the equipment installed with this mount.
The clamp connection consists of two fittings, a seal and a clamp. The clamp presses the two fittings against the seal and against each other, resulting in a tight connection. We suggest you study what such a clamp is in the video.
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)