Steel flanges - flat, collar, loose. Flanges. Appointment. Execution

Transportation of gaseous, liquid and even bulk compositions today is carried out through special pipelines. Where each differs not only in length and overall dimensions, but also in a number of technical parameters. The main one is the maximum pressure of the transported composition. Hence, there are certain requirements for sealing seams and joints, both the main fittings and the additional elements of pipelines. And here you can not do without flanges that provide maximum tightness, strength and even reusability, which is provided by the steel collar welded flange GOST 12821-80.

Flange flange strife

A wide range of pipelines used, as well as the media transported through them, contributes to the expansion of the species diversity of flanges.

flat flanges according to GOST 12820-80 pipeline they are distinguished by an increased inner diameter compared to the outer one, because they are welded to the rear surface of the pipes;
welded steel collar flange according to GOST 12821-80 butt welded, so its inner diameter is equal to the diameter of the pipe;
threaded flanges according to GOST 9399-81 rarely used;
pipe
fitting
gross
large fasteners
connecting ledge
gaskets
alloy steel
stainless steel
carbon steel.

That allows you to create pipelines with specified technical parameters.

Flange Manufacturing Basics

The most widespread factory manufacturing method is the hot stamping method, produced using special presses. Where the force index does not exceed 4500 kN. Further, lathes are connected to the work, on which further processing of all surfaces is carried out. Today, CNC machines are used. Everything is done as accurately and quickly as possible. Because the collar butt-weld flange GOST 12821-80, for example, is not an element of the fastening spectrum. He, like any other of his analogues, is responsible for the tightness and durability of the connection. Fasteners are attached to it or through it.

Pipeline analogues and flanges of vessels and apparatuses

The wide range of both varieties and requirements of modern transport networks imposes a number of requirements on flanges. Hence there is a flange standardization system different kind. Moreover, there are several such systems in the world.

The domestic manufacturer adheres to the regulatory requirements of the GOST system.

Where are they distinguished:

GOST 12821-80 collar flanges butt-welded steel, reliably seal conveying systems, where the pressure parameter of the transferred medium is 0.1-20.0 MPa;
GOST 12820-80 flat flanges designed for wires with pressure parameters in the range of 0.1-2.5 MPa;
GOST 12822-80 steel loose flanges, fixed with a special welded ring, used in pipelines with a pressure of 0.1-2.5 MPa;
GOST 28759.1/2/3/4-90 flat or ordinary flanges for apparatuses and vessels with welded type of fastening in a regular butt or butt using a gasket with an octagonal or oval cross section;
GOST 28919-91 flanges with fastening of the mouth type;
GOST 9399-81 flat flanges or their threaded counterparts made of steel with a welded type, designed for a pressure of 20.0-100.0 MPa.

OST 34-42-836-86 flat flanges designed as an additional element for retrofitting heat and / or nuclear power plants;
OST 26-842-73 flanges with fastening through a gasket of oval or octagonal shape in cross section, but installed end-to-end by welding;
ATK 26-18-12-96 special threaded flanges for fastening a wide variety of measuring equipment. A distinctive quality is high resistance to corrosion at a pressure of transported media of 4.0-16.0 MPa.

Standards of foreign manufacturers

Foreign manufacturers adhere to their own standards. They have standards ansi flanges" or " asme flanges, which in principle implies similar parameters. The classification is based on the nominal diameter of the flanges Du / DN / Dy, which is expressed in inches. An inch is approximately equal to 2.54 cm. In this case, the conditional pressure or Ru / PN is normalized. What forms classifications like class, pound, psi, pounds per squared inch. Hence, such varieties as 150; 300; 400; 600; 900; 1500; 2000; 2500; 3000; 5000; 10,000; 15,000; 20,000.

Our most common varieties from ANSI / ASME are sizes 16.6 and 16.47, and API - 6A. Where the first standard includes steel flanges butt-welded varieties according to GOST 12821-80 with a nominal diameter parameter of 0.5´´-24´´. Higher models comply with the ASME/ANSI16.47 variation. And the API6A modification introduced by the American Petroleum Institute is close to their own standard from ANSI 16.5 and not only in size. Distinctive here are the materials of manufacture and the pressure required for the required adhesion of the starting materials used in the production process. And also the fact that threaded flanges according to the API system have a higher collar height than their counterparts from ASME16.5. Each of the American standards has an exact analogue of the domestic GOST.

Flanges SO or weld-on steel flat flanges;
Weld Neck or WN - welded collar flanges made of steel;
Socket Weld Flanges or socket flanges, that is, supplemented by a recess for welding;
Threaded Flanges or Screwed - threaded steel flanges;
Lap Joint or Lapped Flange - overlap welded flanges, called loose;
Blind Flanges Flange stubs made of steel.

Each variety allows you to choose exactly those flanges that will provide maximum tightness, durability and proper patency for any even the most highly specialized transportation network.

purpose

Flanges are used to connect fittings to pipelines, connect individual sections of pipelines to each other and to connect pipelines to various equipment.
Flange- usually a flat ring or disk with evenly spaced holes for bolts and studs, used for strong and tight connection of pipes and pipeline fittings, attaching them to machines, apparatus and containers, for connecting shafts and other rotating parts ( flange connection). Flanges are used in pairs (as a set).

purpose
Flanges are used to connect fittings to pipelines, connect individual sections of pipelines to each other and to connect pipelines to various equipment.

Execution
GOST provides for 9 versions of flanges that differ in shape and geometric dimensions of the mating surfaces. The most widely used flanges are the 1st version. flanges on high pressure PN 10.16, 20 MPa cannot be manufactured with the sealing surface of version 1. For flanges operating at high pressures, with aggressive working media, etc., as a rule, other versions are used. Depending on the method of welding flanges to the pipeline, they are of two types:

welded flat;
butt-welded (collar).

Material
Flanges are made of carbon, alloy and stainless steels:

Art 3;
Art 20;
09G2S;
15X5M;
12X18H10T.

GOST 12820-80

Designed to connect pipelines for nominal pressure from 0.1 MPa to 2.5 MPa (from 1 kgf / cm2 to 25 kgf / cm2) and medium temperature from -70 C to +300 C. Flanges must be manufactured with a sealing surface of version 1.2 ,3. It is allowed to manufacture flanges with a sealing surface of execution 4,5,8 and 9. Connecting dimensions and dimensions of sealing surfaces in accordance with GOST 12815-80. Technical requirements, material of flanges, fasteners and gaskets, as well as marking, packaging, transportation in accordance with GOST 12816-80.

GOST 12821-80

Designed to connect pipelines for conditional pressure Ru from 0.1 MPa to 20 MPa (from 1 kgf / cm2 to 200 kgf / cm2) and medium temperature from -70 C to +450 C. Flanges must be manufactured with a sealing surface of version 1, 2, 3, 4, 5, 6, 7, 8, 9; flanges for high pressure Ru 10, 16, 20 MPa (100, 160, 200 kgf/cm2) cannot be manufactured with a sealing surface of version 1. Connecting dimensions and dimensions of sealing surfaces in accordance with GOST 12815-80. Technical requirements, material of flanges, fasteners and gaskets, as well as marking, packaging, transportation in accordance with GOST 12816-80.

GOST 12822-80

Designed to connect pipelines for nominal pressure from 0.1 MPa to 2.5 MPa (from 1 kgf/cm2 to 25 kgf/cm2) and medium temperature from -30 C to +300 C. Rings must be manufactured with a sealing surface of version 1.2 ,3. In technically justified cases, it is allowed to manufacture rings with sealing surfaces of execution 4,5,8 and 9. Connecting dimensions and dimensions of sealing surfaces in accordance with GOST 12815-80. Technical requirements, material of flanges, fasteners and gaskets, as well as marking, packaging, transportation in accordance with GOST 12816-80.

For connecting shafts and other flanged elements.

Flange - the manufacturing process is not so simple

Many domestic manufacturers produce large-sized steel flanges, collar flanges and flange plugs (blind flanges) in accordance with GOST, DIN, ANSI and ASME.
The flange differs in types:
flat flange;
flange collar and threaded.

A flat steel flange is welded to the back of the pipe. Accordingly, the inner diameter of the flat flange is slightly larger than the outer diameter of the pipe.

The collar steel flange is butt welded to the pipe, and its inner diameter is equal to the diameter of the pipe. Collar flanges are used on pipelines at pressures over 16 MPa. Threaded flanges in pipe fittings are used extremely rarely.
The flange also differs in the method of fastening:
pipe flange;
fitting flange;
shaft flange;
flange for body parts.

Sometimes a steel flange is welded or screwed to the ends of the parts to be joined as a separate element. The sealing surface of the flange in pipelines depends on the pressure of the operating medium and the material from which the gasket is made. Gaskets made of cardboard, rubber and paronite are used at pressures up to 40 atm., and asbestos-metal and paronite gaskets - at pressures up to 20 atm. Steel flange with a conical sealing surface - at pressures above 64 atm.
The flange is manufactured by hot stamping at factories using special presses with a force of up to 4500 kN. Then the process continues with drilling and surface treatment on CNC lathes. Flanges do not play the role of fastening parts, but serve as a support for fastening bolts or rivets.

To ensure high tightness, the flange in different versions is connected different ways: using a thorn, groove, cavity or connecting protrusion.

As a material for the production of flanges, carbon, alloy and stainless steel are used.

The use of flange connections in critical sections of the pipeline

Modern pipelines are designed to transport various types of liquids, as well as combustible mixtures and other types of working media. In order for this whole process to occur without any problems, it is necessary that all the components of the system work as a single mechanism. The most dangerous places in the pipeline are the junctions of the pipes with each other, as well as the junction of the equipment and the pipeline. Flanges are mounted on these sections. It is worth noting that special attention must be paid to these connecting parts. After all, the smooth operation of the entire pipeline system depends on how reliable the joints will be. At present, steel flanges differ in several basic characteristics. The most important of them are technological and constructive. According to technological features, round and square flanges are distinguished. Their use is determined by the types of pipes used and stop valves. As for the design features, they depend on the standards governing the production and quality control of flanges in Russia and the CIS countries. Types of standards currently in use:
GOST 12820-80
GOST 12821-80
GOST 12822-80.

GOST 12820-80 covers a flat steel flange, which is connected to the pipeline with two seams. To date, this type of connection is not very popular. GOST 12821-80 - butt-welded steel flange. This type of installation is used for nominal pressures up to 200 kgf/cm2. This results in only one stitch. GOST 12822-80 - free steel flange on a welded ring. In this case, a welded ring is connected to the pipe.

Loose steel flanges

A loose flange on a welded ring according to GOST 12820-80 is used to connect pipelines under pressure from 0.1 MPa to 2.5 MPa and at an ambient temperature from -30oC to +300oC. It is made with a sealing surface of execution 1,2,3. In some cases, it is allowed to manufacture rings with execution 4,5,8 and 9.

Flat steel flanges

Flat welded steel flange according to GOST 12820-80 is used to connect pipelines under pressure from 0.1 MPa to 2.5 MPa and at ambient temperatures from -60o C to +300o C. Such flanges are manufactured with a sealing surface of execution 1,2,3 . Production with a sealing surface of execution 4,5,8 and 9 is allowed.

The flat steel flange is the most commonly used connecting element. For its manufacture are used different kinds steels, of which carbon, alloy and stainless are the most popular. One of the main factors by which a steel flat flange is selected is the value of nominal pressure. As mentioned above, with a value of this value up to 200 kgf / cm.kv. butt welding is used. This is the most secure mounting method. With lower values of internal pressure in the pipeline, the steel flat flange can be welded with two seams, or a mounting element on the welded ring is used. The flat steel flange used for fastening the components of the pipeline is made of various steel grades, selected taking into account the following factors:
the effect of operating temperature on the flat steel flange
conditional pressure effect on the flat steel flange
the impact of the transport medium on the steel flat flange.

It is by the combination of all of the above factors that the selection of connecting elements for all types of pipeline takes place. The technical documentation regulating the selection of materials and types of products for the flow of the working medium through the pipeline describes in detail which products can be used in a particular case. This is due to the type of working medium, and its aggressiveness, and pressure on the pipe walls. Do not forget that the internal pressure can reach very high values, so it is necessary to exclude all possible gaps and accidents. Repairing the piping system can be quite expensive. In some cases, failures in the system can cause a chain reaction and lead to sad consequences. To prevent this from happening, it is necessary to select equipment in strict accordance with the recommendations offered by the regulatory and technical documentation.

Steel collar flanges

Collar flanges - the key to the reliability of the pipeline structure

Collar flange according to GOST 12821-80 is designed to connect pipelines under pressure from 0.1 MPa to 20 MPa and at ambient temperatures from -70oC to +450oC. Manufactured with sealing surface version 1, 2, 3, 4, 5, 6, 7, 8, 9.

The flange connection is widely used in piping systems, hot and cold heating systems, and other industries. Flanges provide a reliable and tight connection of pipes to each other, the connection of pipes to machines and other equipment. Now the so-called collar flanges are widespread, which are flanges welded to the connecting parts of the pipeline. All collar flanges produced and used in Russia must comply with GOST 28919-91 Flange connections of wellhead equipment. Types, basic parameters and sizes?. Type flange connection allocate:
Collar flanges with a gap between the ends,
Collar flanges without a gap between the ends.

They are used as connecting flanges for fittings to connect parts of automatic machines, apparatuses, various tanks and pipelines. For each separate type flange connection, there are two connection options: flange-flange and flange-flange with body. Now collar flanges are made of steel grades St 20, 15Kh5M, 12Kh18N10T, 10Kh17N13M2T, 06KhN28MDT and 09G2S, if necessary, they can be equipped with studs.

At the moment, there are collar flanges on the market for pipelines with pressure from 1.0 MPa to 20 MPa, for which various grades of steel and Constructive decisions. In construction and installation practice, flanges are indicated by a set of numbers and letters, for example, flange 1-65-25 st. Ru", and 25 st. 09G2S GOST 12821-80 is the steel grade and GOST, according to which the flange is made. The main advantage of the flange connection is reliability, simplicity of design and the possibility of replacing components.

In addition, it is impossible not to take into account that collar flanges provide high reliability and tightness of the joint, allow you to connect not only pipes, but also devices, machines and large containers. Flanges now offered on the market are suitable for almost any pipe and pressure, which greatly expands the range of their application. The disadvantages include the need for regular tightening of the flanges, the likelihood of a decrease in tightness, often - big sizes and weight.

The fact is that the design of the flange is extremely simple and even primitive, respectively, for large pipes and systems with high pressure, very large collar flanges are required, which are difficult to mount, disassemble and assemble if necessary. At the same time collar flanges can be used for pipelines with liquid and gaseous media and operated at temperatures from -40 to +200 degrees Celsius. Now collar flanges are indispensable when installing butterfly valves, since in this case it is possible to choose a flange with an inner diameter equal to the diameter of the valve.

In the case of using flat flanges, it is necessary to take flanges with a large internal diameter, which interferes with the clamping of the elastomer and even destroys it over time. But collar flanges ensure the correct and uniform clamping of the saddle seal. As already mentioned, in Russia flanges are manufactured in accordance with GOST, it is also possible to produce products that meet Western standards: ANSI (American national institute standards), ASME (American Society of Mechanical Engineers), DIN (German Institute for Standardization) and OST (industry standards). It is also possible to manufacture flanges according to customer drawings.

Our Firm offers a full range of pipe fittings, including flanges, bends, transitions from one pipe diameter to another. with an assortment and technical specifications You can find it on the website page.