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Ifs connection. Insulating flange connections

It is a combination of two or three flanges, between which are installed gaskets made of insulating material. Apart from gaskets, in the holes for fasteners, additional insulating sleeves. can act as an insulating material paronite, graphite And fluoroplast. insulating flange connections(abbreviated as IFS) are used to protect the pipeline or any section of the pipeline from electrochemical corrosion. Electrochemical corrosion appears on the pipeline as a result of the influence on the pipeline of electrical, or so-called "stray" earth currents. As a result of the impact of such corrosion on the pipeline, cracks are formed on the pipeline, and leakage of the transported medium may occur. Wandering earth currents appear on those parts of the earth where the earth is used as a conductive medium. These are areas located near tram or railway depots and tracks, as well as near any power plants. (IFS) isolate the pipeline section from stray currents by interrupting the metal structure of the pipeline with an insulating material, thereby preventing the occurrence of electrochemical corrosion. In the figure below, you can see how schematically they look :

As can be seen from the schematic diagram above, represents a from insulating gasket between flanges, as well as with bushings in mounting holes. This type is used in most cases of pipeline laying, but in the gas industry, where the transported medium is gases with an overpressure of not more than 7.0 MPa, another type is used insulating flange connections are compounds made up of three flanges. In the figure below, you can see how schematically they look insulating flange connections (IFS) consisting of three flanges:

As can be seen from the diagram above, this insulating flange connection (IFS) represents a connection of two collar flanges welded to the pipeline, through the third flange, which is between them. Between flanges also available insulating gaskets, and in the holes for fasteners are installed insulating sleeves. As a third flange, usually acts flat flange, the thickness of which does not exceed 20mm. Everything gaskets for IFS are covered with a special electrically insulating bakelite varnish, this is done to protect the gaskets from moisture saturation.

Insulating flange connections are of the following types

  • - insulating flange connections
  • - insulating wafer connections
  • - detachable insulating flange connections
  • - insulating flange connections one-piece

Usually, insulating flange connections (IFS) are used in pipelines in the following cases:

  • near objects that are sources of stray currents;
  • on branches of the pipeline from the main line;
  • in order to disconnect an electrically insulated conduit from any non-insulated earthed structure;
  • at the junction of pipelines that are made of different metals;
  • in order to disconnect an electrically insulated pipeline from any explosive underground structure;
  • when entering a heating network to objects that are sources of stray currents;
  • at gas distribution points and gas distribution stations, etc.

Insulating flange connections produced according to two main regulatory documents: GOST 25660-83 And TU 3799. IFS according to GOST 25660-83 can be made in one version. In the figure below, you can see how this implementation looks schematically:

Insulating flange connections according to GOST 25660-83 are used to protect underwater, underground and surface pipelines from electrochemical corrosion at a pressure of 10.0 MPa and an ambient temperature not exceeding 80°C.

IFS according to GOST 25660-83 manufactured and assembled exclusively in the factory, because when assembling, you must follow a certain clear sequence, namely:

  1. Before assembly IFS, flange sealing surface covered with a special insulating varnish.
  2. Hardware with which insulating flange connection connected, isolated with bushings or insulating gaskets from flanges.
  3. flanges are connected by sequential tightening of diametrically opposite studs in order to avoid their distortion.
  4. After insulating flange connection assembled, ends insulating gaskets and washers, as well as the inner surface of pipes and flanges covered with insulating varnish, and flanges dried at temperatures up to 200 °C.

After assembly, insulating flange connections according to GOST 25660-83 pass certain electrical and hydraulic tests provided by the documentation developed by the manufacturer IFS, and are also checked for compliance with the general requirements, which are set out in the "Rules for the device and safe operation technological pipelines". IFS according to GOST 25660-83 tested in a dry room, using a megohmmeter, at a voltage of 1000V, and insulating flanges tested both wet and dry.

Insulating flange connections according to GOST 25660-83 can withstand pressure up to 10.0 MPa, and their diameter varies from 200mm to 500mm. The table below shows all types IFS according to GOST 25660-83 supplied by our company, as well as the characteristics of the data IFS:

Insulating flange connections according to GOST 25660-83:

Conditional passage Dyd1DD1dshl1, sq at leastHWeight, kg, no more
200 190 430 360 M36 2,0 293 129,6
250 236 505 430 333 195,2
300 284 585 500 M42 375 303,8
350 332 655 560 M48 2,5 405 411,3
400 376 715 620 414 502,2
(450) 456 770 675 3,0 459 615,2
500 506 870 760 M56 499 843,4

Below is an example symbol insulating flange connections according to

INSULATING FLANGED CONNECTIONS

The plant of details of pipelines "RECOM" makes insulating flange connections according to TU 3799-005-31049454-2009. IFS manufactured by the RECOM plant are guaranteed to provide electrical isolation of one section of the pipeline from another in order to counteract electrochemical corrosion.

PURPOSE OF INSULATING FLANGED CONNECTIONS (IFS)

They are used to ensure the protective electrical potential of electrochemical protection installations (cathode ECP) ​​of gas distribution stations (points) of GDS (GRP). They provide interruption of the flow of electric current through pipelines (electrical conductivity), also to protect various underground utilities from electrocorrosion. It is placed in the open air on pipelines at the input and output of the GDS (GRP) buildings, residential buildings in various climatic zones.

The design of the IFS consists of two flanges, an insulating gasket between them, insulating bushings that are installed in the mounting holes, as well as studs, nuts, and insulating washers.

TECHNICAL CHARACTERISTICS OF IFS

Maximum allowable pressure (no more, MPa) 10,0
Conditional pass, Du
20...1200

Workspace

 Fresh and superheated water, saturated and superheated steam, air, inert gases, natural gas and LPG, heavy and light oil products, oils
Working environment temperature, not more than °С +350°С
Material performance
Steel 20, 09G2S, 12X18H10T, VT 0.1
Climatic version according to GOST 15150-69 У1 (-40°С...+40°С)
ХЛ1 (-60°С...+40°С)
Water absorption of insulating materials no more than 0.01%
Dielectricity of the insulating gasket in a dry state, Ohm
0,2*106
Dielectricity of the insulating gasket in the wet state, Ohm
10*103

CLASSIFICATION OF IFS MANUFACTURED BY ZDT RECOM LLC

Parameters IFS classification
IFS type Type 1-1 Type 2-3 Type 7-7
Nominal pressure, MPa up to 2.5 up to 6.3 up to 10.0
Working temperature,°C no more than 300°C
Climatic performance U/HL
Insulation resistance, KΩ 200
Flange execution in accordance with GOST 12815-80 1-1 2-3 7-7
1. IFS 1-1 up to 2.5 MPa (25kgf/cm2)

1. Flanges according to GOST 12821 (version 1-1);

2. Insulating gasket;

3. Bushings insulating;

4. Insulating washer;

7. Nuts for flange connections GOST 9064;

2. IFS 2-3 up to 6.3 MPa (63kgf/cm2)


1. Flanges according to GOST 12821 (version 2-3);

2. Insulating gasket;

3. Bushings insulating;

4. Insulating washer;

5. Washers for flange connections GOST 9065;

6. Studs for flange connections GOST 9066;

3. IFS 7-7 up to Ru 10.0 MPa

1. Flanges according to GOST 12821 (version 7-7);

2. Insulating gasket;

3. Bushings insulating;

4. Insulating washer;

5. Washers for flange connections GOST 9065;

6. Studs for flange connections GOST 9066;

7. Nuts for flange connections GOST 9064.

In order to correctly place an order for the production of IFS at ZDT RECOM LLC, it is necessary to indicate in the application:

1. Product name - IFS;

2. Nominal passage Dy, mm;

3. Nominal pressure Ru, MPa (kgf / cm 2);

4. Brand of material - art. 20, art. 09G2S, Art. 12X18H10T, art. 15X5M, VT 1-0, etc.

Additionally:

1. Working temperature, ºС;

2. Working environment.

Symbol example:
IFS 50-63 2-3 Art.20
IFS 50-16 1-1 Art.20
IFS 50-160 7-7 Art.20

If you are interested in purchasing IFS, you can fill out the terms of reference and send it to ZDT RECOM LLC.

Consequences of exposure to electrochemical corrosion on pipelines

Ensuring electrochemical protection is provided for by official documents:

VSN-009-88 – Departmental building codes “Construction of main and field pipelines. Means and installations of electrochemical protection.

GOST R 51164-98 - Main steel pipelines. General requirements for corrosion protection, etc.

Insulating joints are used on pipelines to provide electrochemical protection.

Insulating flange connections (IFS) are two flanges connected to each other and welded to the two ends of the pipeline. To achieve electrical isolation between them, a two-millimeter paronite gasket coated with bakelite varnish is installed.

Thus, it simultaneously does not absorb moisture and avoids the passage of electric current through the pipeline. Sometimes gaskets are also made from PTFE or vinyl plastic. The IFS also contains tightening studs, polyamide bushings, washers and nuts. Thanks to these hardware, the flanges are pulled together and fixed in this position. Order only from us.

In general, insulating flange connections are a strong connection between two pipeline elements. An important role in it is played by an electrically insulating gasket, which makes it possible to exclude the ingress of electric current into the pipeline. On average, the resistance of one insulating flange connection is at least 1000 ohms.

Insulating flange connections

IFS is a composite structure produced in the conditions of the enterprise, which has the necessary tightness and isolation. Its main function is to cathodically protect underground and above-ground pipes and thus extend their service life.

Installation process

  • The installation of the IFS is carried out at the place where the pipes come out of the ground and at the entrance to it. The need for its installation is due to the likelihood of the pipe coming into contact with electrical contacts, grounding and other communications. Including at the outlets of pipelines of GDS, GRU, GRP.
  • The installation of the IFS is immediately included in the project during its preparation and is carried out by special installation teams.

The site company specializes in the creation of IFS from various steel grades using electrically insulating gaskets from:

  • fluoroplast,
  • paronitis,
  • vinyl plastic.

Our company is ready to produce these designs of any diameter specified by the customer. Production is carried out on the basis of GOST. For example, we offer products from high-carbon brand 09g2s with steel hardware 40x., Fluoroplastic bushings.

We keep all guests

Production is regulated by GOST 12816. More detailed information about our capabilities, standard products that we design can be found on the website of the company "site". You can also leave a request or contact us by phone and e-mail. We accept orders for manufacturing throughout Russia and also organize the delivery of IFS to the customer's address.

Insulating connections

Insulating flange connections are provided to customers already assembled. All of them undergo special tests in independent laboratories cooperating with the company. The insulating and hermetic characteristics of the product are studied. After the client receives the products in his hands, it is highly not recommended to disassemble the IFS, since there is a high probability of loss of insulating qualities after self-assembly. Installation on the IFS pipeline is carried out using welding equipment.

Send your drawings or sketches to

Or call 8-800-250-88-72. Delivery across Russia and the CIS!!!

IFS are designed to block the ingress of stray electric current into the pipeline. To do this, the flange connection, assembled at the enterprise, is equipped with insulating gaskets made of dielectrics (textolite, paronite, klinergit, etc.). Insulating materials are placed not only between the flanges, hardware is also made from special materials:

  • washers,
  • bushings,
  • hairpins,
  • nuts, etc.

In other words, FSIs are used to create electrical sectioning of parts that are located underground and above it. The safety of the gas pipeline depends on the form in which the flanges will be contained.

In the manufacture insulating flange connections and installation in hazardous places (with compressor stations, tanks, etc.), where the magnitude of the current in the pipelines can be high, it is necessary to regularly check and prevent the working condition of the IFS. For this, the insulating flanges must be located in specially created working wells.

Such structures must necessarily be equipped with control conductors that go outside. This is necessary so that service workers can carry out the necessary electrical measurements without descending into the well.

IFS are not only used as protective structures on pipelines from the corrosive effects of electric current, they are also installed when gas and oil products approach pumping stations and other structures.

The topic of insulating flange connections is relevant today for many enterprises.

The insulating flange connection is one of the elements of the pipeline system and is designed to protect against the effects of electrochemical corrosion.

Since a large number of pipelines are laid underground, the problem of electrochemical impact on the pipeline is acute for those who operate these systems.
Electrochemical corrosion of pipelines is a consequence of the influence of electric currents of the earth, or, as they are also called, stray currents. Electric currents penetrate pipes that have insulation defects. Penetrating into the pipeline, electric current forms a cathode zone at the point of penetration, which is not dangerous for the system, but a dangerous anode zone is formed at the point of current exit, which leads to the destruction of the metal as a result of the current. The consequences of such an impact may be: the destruction of the metal, the formation of cracks, which in turn leads to the leakage of gas, water, oil, etc. Such changes in the system can lead to emergency situations.
Ensuring electrochemical protection is provided for by official documents, namely: Departmental building codes “Construction of main and field pipelines. Means and installations of electrochemical protection” (VSN - 009-88), GOST R 51164-98 “Steel main pipelines. General requirements for corrosion protection”, etc.
Insulating joints are used on pipelines to provide electrochemical protection.

Insulating connection (IC). IP classification
Formally, insulating compounds can be classified as follows (Fig. 1):

Currently, the most common IC design is the insulating detachable flange connection.

Insulating flange connection
An insulating flange connection is a structure consisting of flanges, insulating rings (gaskets) between them, insulating bushings that are installed in the mounting holes, as well as studs, nuts, washers.

Purpose and conditions of use
IFS is used as one of the means of protection against electrochemical corrosion of underwater and underground (ground) pipelines.
An insulating flange connection is installed in the following cases:
on pipelines near objects that can be sources of stray currents (tram depots, power substations, repair bases, etc.);
on branch pipelines from the main line;
for electrical disconnection of an insulated pipeline from non-insulated grounded structures (gas pumping, oil pumping, water pumping stations, field communications, pipelines, art wells, tanks, etc.);
when connecting pipelines made of various metals;
for electrical separation of pipelines from explosive underground structures of enterprises;
at the outlet of the pipeline from the territory of the supplier and the entrance to the territory of the consumer;
at the input of the heating network to objects that can be sources of stray currents;
on the above-ground vertical sections of inputs and outputs of hydraulic distribution stations (gas distribution points) and GDS (gas distribution stations);
for electrical disconnection of pipelines from underground structures of enterprises where protection is not provided or prohibited due to explosion hazard.

Designs of insulating flange connections
At the moment, we know one national regulatory and technical document that regulates the design and dimensions of the IFS - GOST 25660-83 "Insulating flanges for underwater pipelines at Ru 10 MPa", but each manufacturer in the manufacture of IFS is guided by the requirements of the customer and according to these requirements designs the connection.
Considering the design features of the insulating flange connection, the following types can be formally distinguished:
IFS according to GOST25660-83;
IFS, consisting of three flanges;
IFS manufactured by Gazavtomat LLC (with the use of butt-welded flanges of 2 and 3 versions).
Recommendations for the manufacture of IFS, which are worth paying attention to, are spelled out in the "Rules for the Design and Safe Operation of Process Pipelines" (PB No. 003.585-03 dated 10.06.2003).
Consider various designs of IFS (Fig. 2,3,4).


IFS according to GOST 25660-83
The assembled IFS according to GOST 25660-83 is used for electrochemical protection against corrosion of underwater, underground and surface pipelines at a pressure of 10.0 MPa (100 kgf/cm2) and an ambient temperature not higher than 80 0C.
Technical requirements to flanges are set out in GOST 12816-80 "Flanges of fittings, fittings and pipelines for Ru from 0.1 to 20.0 MPa".
The ring for this connection can be made of textolite (according to GOST 5-78), fluoroplast (according to GOST 10007-80) or paronite (GOST 481-80). This is due to the fact that these types of materials are quite moisture resistant and do not allow negative impact external environment on connection elements.
According to GOST 25660-83, gasket and bushing materials must have the following properties:
breaking load - not less than 260 MPa;
electrical resistance - not less than 10 kOhm;
water absorption - no more than 0.01%.
Also, to ensure electrochemical insulation, it is necessary to cover the surfaces of the flanges that come into contact with the gasket with a special electrically protective material, polytetrafluoroethylene or a composition based on fluoroplast grade F 30 LN-E. Coating thickness 0.2 (±0.05) mm. The coating must be of equal thickness and glossy, and also must not have delaminations or swellings, porosity, cracks and chips.

IFS consisting of three flanges
FSI data are widely used in the gas industry.
In their design (Fig. 3), in addition to two main flanges welded to the ends of the gas pipeline, there is a third flange, the thickness of which depends on the diameter of the gas pipeline and is in the range of 16-20 mm. To electrically isolate the flanges from each other, paronite gaskets are installed between them. Gaskets are coated with an electrically insulating bakelite varnish in order to protect them from moisture saturation. Electrically insulating gaskets can also be made of vinyl plastic or fluoroplastic.
Tightening studs are enclosed in split sleeves made of fluoroplastic, insulating gaskets made of paronite coated with bakelite varnish are also provided between the washers and flanges. Along the perimeter of the flanges there are threaded sockets into which screws are screwed, used to check the electrical resistance between each main flange and the intermediate one.
These IFS are installed on Du from 20 mm. The design mainly uses flanges according to GOST 12820-80.
The disadvantage of such a connection can be considered that it can withstand pressure only up to 2.5 MPa.
IFS, as a rule, are mounted on the above-ground vertical sections of inputs and outputs of hydraulic fracturing and gas distributing stations. To control the serviceability and repair of the IFS, they must be installed after the shut-off valves along the gas flow at a height of no more than 2.2 m.
For these IFSs, the resistance (assembly) in the wet state must be at least 1000 ohms.

IFS manufactured by Gazavtomat LLC
This type of IFS was developed by Gazavtomat LLC and complies with the requirements of all necessary regulatory and technical documents.
The main difference of this insulating flange connection is that its design uses two flanges according to GOST 12821-80 "Butt-welded steel flanges for Ru from 0.1 to 20.0 MPa": 2nd version (with a ledge) and 3 -th version (with a cavity) - with minor design modifications (the size of the protrusion is reduced and the size of the cavity is increased). This is due to the need to provide greater electrical insulation and tightness of the system. These IFS can be used for pipelines operating at nominal pressure up to 6.3 MPa and at temperatures up to 300 °C. I would like to note that the use of flanges of the 2nd and 3rd versions according to GOST 12821-80 is not accidental. In accordance with building codes and regulations (SNiP 2.05.06.85), as well as safety rules (PB) dated 10.06.2003 No. 03-585-03, it is recommended to use flanges of these designs for IFS, which ensures a high level of technological safety. pipelines.
The whole structure reliably isolates two sections of the pipeline from each other, interconnected by an insulating flange connection.
An insulating gasket is installed between the flanges, insulating bushings are installed in the fastener holes, insulating gaskets are provided between the nut washers and flanges. The material of the gasket, insulating bushings and washers must satisfy the tightness conditions of the flange connection at the operating parameters of the pipeline (pressure, temperature).
As the insulating material to be laid, paronite is used, which is pre-dried, which makes it possible to increase the electrical resistance. To protect the gaskets from moisture saturation after manufacturing, they are carefully covered with electrically insulating bakelite varnish (BT-99).

IFS assembly
The manufacture and assembly of the IFS is carried out in the factory.
When assembling insulating flange joints, a clear sequence must be observed:
1) before assembly, the sealing surfaces of the flanges are coated with insulating varnish or special spraying (IFS according to GOST 25660-83);
2) IFS fasteners are isolated from the flanges with bushings (GOST 25660-83) or insulating gaskets;
3) in order to avoid distortion, the flanges are connected by sequential tightening of diametrically opposite studs;
4) before and after assembly, the ends of the insulating gaskets and washers, as well as the inner surface of pipes and flanges, are coated with insulating varnish, and the flanges are dried at temperatures up to 200 °C.

IFS tests
In addition to the fact that FSIs are subjected to tests, which are provided for by the documentation developed by the FSI manufacturer, there are General requirements according to the tests that are set out in the "Rules for the Design and Safe Operation of Process Pipelines". According to this document, the assembled FSI must pass electrical and hydraulic tests.
The assembled insulating flange connection is tested in a dry room with a megger at a voltage of 1000 V.
During electrical tests, insulating flanges are checked both in a wet and dry state with a special device - a megohmmeter. These tests must be carried out in the following sequence:
between flanges;
between each flange and each stud.
In order to carry out the so-called wet tests, it is necessary to douse the IFS with water and hold it for one hour.
Dry insulation resistance requirements:
between flanges - not less than 0.2 MΩ;
between each flange and each stud - at least 1 MΩ.
Wet insulation resistance requirements:
between flanges - not less than 1000 Ohm;
between the flange and the stud - at least 5000 Ohm.
For hydraulic tests for the strength and tightness of the connection, the method of pressure testing with water on a special stand is used. Crimping is done with a hydraulic hand pump.
Unfortunately, hydraulic testing leads to a rise in the cost of products several times, which, most often, does not suit the client. In this case, it is possible, in agreement with the customer, not to carry out these tests, since they will still be carried out at the installation site during the verification of the entire system.
An act must be drawn up for electrical and hydraulic tests.