Type of connection to the pipeline. Comparison of dependent and independent heating systems. Video: installing a flanged LD ball valve on a pipe using

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 with a diameter of 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 of various grades. 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 overall dimensions of the 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 of 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 a thread on a pipe using special tools if it does not exist and the equipment has not been installed before. 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 for making threaded connections: internal or external thread. The fittings may have an internal thread on one side and an external thread on the other, 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.
• They do not require additional parts for installation, such as the 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 tap to a pipe, you will not have to tighten the bolts, as with a flange connection, and 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 simplest welding method.

Advantages of a welded connection

• Absolute tightness when the welding procedure is performed correctly.
• 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)

A modern quick-release connection for pipeline fittings, used mainly in the 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.

Ball valve is one of the most popular types of pipeline fittings. One of its main classifying features is the method of attachment. “Coupled”, “flange”, “welded” are commonly used attachments for ball valves. Less commonly used are “pin”, “nozzle”, “nipple”, “solder”.

Types of connections for industrial pipeline fittings are defined in the current interstate standard GOST 24856-81 (analogous to ISO 6552-80). In the “description” cell of the GOST table of terms and definitions regarding types of connections there is a dash; there is only a graphic sketch. It is understood that the meaning of the term should be clear literally from the name. However, for a person who is not interested in technology, the marking “socket ball valve” or “flanged ball valve” may be incomprehensible.

Ball valves by connection type

Coupling

The coupling ball valve is connected using internal threads cut into the body along the edges. A coupling is a connecting part of pipelines that has the shape of a hollow cylinder with a thread cut inside.
Socket ball valves are often used in both the domestic and industrial sectors. They are very convenient, since installation requires only a pair of wrenches (open-end, pipe, adjustable) depending on the installation location. To prevent leakage, the threads of the coupling valve are packed with strands of flax with Unipack, FUM tape, sealing thread or anaerobic sealant. Installation of a coupling ball valve is quick, and the fittings themselves are relatively inexpensive. The most commonly used sizes are corresponding to the connecting thread ½, ¾, 1, 1 ¼, 1 ½, 2 inches. Also on the market there are smaller diameters - ¼, ⅜ inches, large ones - 2 ½, 3, 4 inches.

Flanged

The connection of a flanged ball valve is made in the form of a flat, most often round, part located perpendicular to the axis, with holes for fasteners (bolt and nut). There are always two flanges in the connection. One on the pipe, the second on the fittings. The flange connection is highly reliable. The thickness of the flange and the number of holes depends on the maximum pressure for which the ball valve is designed. In the domestic sector, flanged ball valves are practically not used, except when connecting to a central water supply or gas pipeline. Such shut-off valves are mainly used in public utilities and industry.

Welded

Weld-on ball valves are mounted on the pipeline by welding. The connecting pipes of such fittings are made in the shape of a pipe and do not have threads or connecting parts. They are often also called (as GOST 24856-81 regulates) “ball valves for welding.” Weld-on ball valves can be made of carbon, low-alloy, stainless steel, and have a one-piece or collapsible design. The scope of application of welded fittings is industry and public utilities.

Fittings

Union ball valves are similar in design to coupling valves, with the only difference being that the thread on the connecting pipe is not internal, but external. The selection of a coupling or fitting product is made based on the thread on the mating part. Sellers, installers, and many manufacturers call such fittings “nipple taps,” which is the same thing. Their distinctive feature is connections with external threads. The price of a coupling ball valve is lower than that of a nipple valve. The installation and standard sizes of such fittings are mostly similar.
A ball valve with external thread can be equipped with half-bends on one or both sides. Such a connection will be dismountable and the valve can be removed for replacement or maintenance. The half fitting can be threaded or welded. A fitting with a half-fitting on one side is often called an “American tap”.

Tsapkovye

The pin-type ball valve has connecting pipes (one or both) with external threads and a collar. Such products are intended for installation directly on a tank, equipment (boiler, boiler), etc. An example of trunnion cranes can be seen below. For example, these are taps with a fitting for irrigation, water taps, drainage taps.

Solderable

Connection of ball valves is also possible by soldering. Basically, such fittings are installed on copper and polypropylene systems. The use of solder ball valves makes the connection more durable and aesthetically pleasing; the use of additional fittings is not required. It should be noted that it is correct to use the word “welding” when referring to polypropylene, but “soldering” is more often used among installers and consumers.

Names of ball valves

It just so happens that the standard establishes certain terms for fittings, installers and designers use others, and Chinese manufacturers use others. Here are some commonly used names and their meanings:

• ball valve NN - fittings on both sides with external thread (other names, “male-male”, “fitting on both sides”, “nipple”);
• ball valve BB - fittings on both sides with internal thread (“female-female”, “coupling”);
• ball valve VN has an external thread on one side and an internal thread on the other (“male-female”);
• faucet with a gander - pin-type water dismounting with a fitting for a hose;
• American tap - fittings with a collapsible connection (with a half-fitting).

Threaded and other shut-off valves can be the same type of connecting pipes or different - combined. For example, a ball valve has an internal thread on one side and an external thread on the other (VN). Or one connection is flanged and the other is welded.

Large selection of ball valves in our UniDim online store. Our brands are GIACOMINI, RBM, WATTS.

Electric drives are produced with the highest torques from 0.5 to 850 kgf-m in normal and explosion-proof versions with different explosion protection categories. These and other parameters of electric drives are reflected in the drive designation, consisting of nine characters (numbers and letters). The first two characters (numbers 87) indicate an electric drive with an electric motor and gearbox. The next sign is the letter M, A, B, C, D or D, indicating the type of connection of the electric actuator to the valve. The M type connection is shown in Fig. II.2, types A and B - in Fig. II.3, types B and D in - fig. II.4, type D - in Fig. P.5. The dimensions of the connecting elements are given in table. 11.106.

11.106. Dimensions of connecting elements of unified electric drives of valves

All electric actuators are connected to the valves using four studs. The diameters of the studs and the dimensions of the supporting pads are different for different types of connections. With an increase in the torque developed under water, they increase. In connections of types B, D and D, two keys are provided in order to relieve the studs from shearing forces created by the torque transmitted from the drive to the valve.

The next figure conventionally indicates the torque of the electric drive. A total of seven gradations are provided for the general range of torques from 0.5 to 850 kgf-m (Table 11.107). Within the specified interval, adjustment to the required torque is made by adjusting the torque limiting clutch.

11.107. Symbols for electric drive parameters

The next number conventionally indicates the rotational speed (in rpm) of the drive shaft of the electric drive, which transmits rotation to the valve running nut or spindle. There are eight rotation frequencies of the electric drive drive shaft - from 10 to 50 rpm (Table 11.107).

Then the conditionally complete number of revolutions of the drive shaft is indicated, which it can make depending on the design of the box of limit and torque switches. There are six gradations in total (Table 11.107).

This limits the first group of signs. The second group consists of two letters and a number. The first letter of the second group of designations indicates the design of the drive according to climatic conditions: U - for moderate climates; M - frost-resistant; T - tropical; P - for elevated temperature. The second letter indicates the type of connection of the control cable to the electric drive box; Ш - plug connector; C - gland entry. The last digit indicates the explosion protection version of the drive. Number 1 indicates normal version H; the remaining numbers from 2 to 5 indicate explosion protection categories: 2 - VZG category; 3 - category B4A; 4 - category V4D; 5 - category RV. Thus, the electric drive under the designation 87B571 US1 has the following data: 87 - electric drive; B - type of connection; 5 - torques from 25 to 100 kgf-m; 7 - drive shaft rotation speed 48 rpm; 1 - total number of revolutions of the drive shaft (1 - 6); U - for temperate climates; C - control cable gland entry; 1 - standard explosion protection version N.

Below are brief technical characteristics and dimensional data of electric drives of the unified series.

Electric drives of normal design with M type connection with a double-sided torque limiting clutch (Fig. A.6). Symbols 87M111 USH1 and 87M113 USH1. Designed to control pipeline fittings in structures with a maximum torque of up to 2.5 kgf-m. Torque control limits are from 0.5 to 2.5 kgf-m. The total number of revolutions of the drive shaft is 1 - 6 (87M111 USH1) and 2 - 24 (87M113 USH1). Drive shaft rotation speed 10 rpm. The drive is equipped with an AB-042-4 electric motor with a power of 0.03 kW and a rotation speed of 1500 rpm. Gear ratio from the handwheel to the drive shaft = 1. A force of up to 36 kgf can be applied on the flywheel rim. Electric drives have a built-in box! travel and torque switches. Electric drive weight 11 kg. The overall dimensions of electric drives 87M111 USH1 and 87M113 USH1 are shown in Fig. P.6.

11. 108. Symbols of electric drives

11.109. Brief technical characteristics and weight of electric drives

11.110. Symbols of electric drives

Electric drives of normal design with type A connection with a double-sided torque limiting clutch (Fig. II.7). The maximum torques created by the drives are 6 and 10*kgf-m. There are eight modifications of electric shelters (Table 11.108). Technical characteristics and weight of electric drives are given in table. 11.109. Electric motor shaft rotation speed 1500 rpm Gear ratio from the handwheel flywheel to the drive shaft i = 3. Electric drives have a built-in box of travel and torque switches. Overall dimensions of electric drives are shown in Fig. P.7.

Electric drives of normal design with connection type B with a double-sided torque limiting clutch (Fig. II.8). The maximum torque on the drive shaft is 25 kgf-m (control interval from 10 to 25 kgf-m). There are twelve modifications of electric drives (Table 11.110). Technical characteristics of electric drives are given in table. 11.111. Motor shaft rotation speed 1500 rpm. Overall dimensions of electric drives are shown in Fig. II.8. Electric drive weight 35.5 kg.

11.111. Brief technical characteristics of electric drives

Electric drives of normal design with connection type B with a double-sided torque limiting clutch (Fig. II.9). The maximum torque on the shaft is 100 kgf m (control interval from 25 to 100 kpm). There are twelve modifications of electric drives (Table 11.112). Technical characteristics and weight of electric drives are given in table. II. 113. Waxing frequency of the electric motor shaft is 1500 rpm. The overall dimensions of the electrical wires are shown in Fig. II.9.

Electric drives of normal design with connection type G with a double-sided torque limiting clutch (Fig. 11.10). The maximum torque on the shaft is 250 kgf-m (control interval from 100 to 250 kgf). There are twelve modifications of electric drives (Table 11.114). Technical characteristics and weight of electric drives are given in table. 11.115. Motor shaft rotation speed 1500 rpm. Overall dimensions of electric drives are shown in Fig. UFO.

11.112. Symbols of electric drives

11.113. Brief technical characteristics and weight of electric drives

11.114. Symbols of electric drives

11.115. Brief technical characteristics and weight of electric drives

Electric drives of normal design with connection type D with a double-sided torque limiting clutch (Fig. 11.11). The highest torque on the drive shaft is 850 kgf-m (control interval from 250 to 850 kgf-m). Drive shaft rotation speed 10 rpm. There are six modifications of electric drives (Table 11.116). The gear ratio from the flywheel to the drive shaft is i = 56. The permissible force on the rim of the handwheel flywheel is 90 kgf. Electric drives are equipped with an AOS2-42-4 electric motor with a power of 7.5 kW and a shaft speed of 1500 rpm. Electric drive weight 332 kg. Overall dimensions of electric drives are shown in Fig. 11.11.

Rice. 11.12. Electrical control circuit for electric drives of a unified series:

D - asynchronous electric motor with a squirrel-cage rotor; KVO, KVZ - track microswitches MP 1101 for opening and closing; KV1, KV2 - additional track microswitches MP 1101; VMO, VMS - torque microswitches MP 1101 for opening and closing; O, 3 - magnetic opening and closing starters; LO, LZ, LM - signal lamps “Open”, “Closed” and “Coupling”; KO, KZ, KS - control buttons “Open”, “Closed” and “Stop”; 7 - potentiometer PPZ-20, 20 kOhm; Pr - fuse; A - automatic; 1 - 4 - microswitch contacts

Explosion-proof electric drives are also available:

11.116. Symbols of electric drives

The electrical control circuit for electric drives (same for all) is shown in Fig. Item 12. In the “Open” position the LO signal lamp is on, in the “Closed” position the LM and LM lamps are on, in the “Emergency mode” position the LM lamp is on. The operation of microswitches is clear from the table. 11.117.

11.117. Operation of microswitches (Fig. 11.12)

In apartment buildings, residents mainly use the central heating network to heat the premises. The quality of these services is influenced by many factors: the age of the house, wear and tear of equipment, the condition of the heating main, etc. A special scheme for connecting to the heating network is also of significant importance in the heating system.

Connection types

Connection schemes can be of two types: dependent and independent. Connecting using the dependent method is the simplest and most common option. An independent heating system has gained popularity recently and is widely used in the construction of new residential areas. Which solution is more effective for providing warmth, comfort and coziness to any room?

Dependent

This connection scheme, as a rule, provides for the presence of in-house heating points, often equipped with elevators. In the mixing unit of the heating station, superheated water from the main external network is mixed with the return water, thereby acquiring a sufficient temperature (about 100°C). Thus, the internal heating system of the house is completely dependent on external heat supply.

Advantages

The main feature of this scheme is that it provides for the supply of water to the heating and water supply systems directly from the heating main, and the price pays off quite quickly.

Flaws

Along with the advantages, such a connection also has some disadvantages:

• uneconomical;
• temperature control is significantly difficult during weather changes;
• overconsumption of energy resources.

Connection methods

Connection can be made in several ways:

Independent

An independent heat supply system allows you to save consumed resources by 10-40%.

Operating principle

The consumer heating system is connected using an additional heat exchanger. Thus, heating is carried out by two hydraulically isolated circuits. The external heating circuit heats the water of the closed internal heating network. In this case, mixing of water, as in the dependent version, does not occur.

However, such a connection requires considerable costs for both maintenance and repair work.

Water circulation

The movement of the coolant is carried out in the heating mechanism thanks to circulation pumps, due to which there is a regular supply of water through the heating devices. An independent connection circuit may have an expansion vessel containing a supply of water in case of leaks.

Components of an independent system.

Scope of application

Widely used to connect multi-storey buildings or structures to the heating system, which require an increased level of reliability of the heating mechanism.

For facilities that have premises where access to outside service personnel is undesirable. Provided that the pressure in return heating systems or heating networks is higher than the permissible level - more than 0.6 MPa.

Advantages

Negative points

• high price;
• difficulty of maintenance and repair.

Comparison of the two types

The quality of heat supply according to a dependent scheme is significantly affected by the operation of the central heat source. This is a simple, cheap method that does not require special maintenance or repair costs. However, the advantages of a modern independent connection scheme, despite the financial costs and complexity of operation, are obvious.