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 insulation 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 (cathodic 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 |
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Working environment |
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 °C | +350°C |
| Material execution |
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
| Options |
IFS classification |
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| 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, ° С | no more than 300°C | ||
| Climatic performance | U/HL |
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| Insulation resistance, KΩ |
200 |
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| Flange execution in accordance with GOST 12815-80 | 1-1 | 2-3 | 7-7 |
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.
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.
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. Entering the pipeline electricity forms a cathodic zone at the point of penetration, which is not dangerous for the system, but at the point of current exit a dangerous anode zone is formed, which leads to the destruction of the metal as a result of the current. The consequences of such an impact may be: destruction of the metal, the formation of cracks, which in turn leads to 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: building codes“Construction of main and field pipelines. Means and installations of electrochemical protection "(VSN - 009-88), GOST R 51164-98" Main steel 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 uninsulated 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 is prohibited due to explosion hazard.
Designs of insulating flange connections
At the moment, we are aware of one nationwide regulatory and technical document regulating the design and dimensions of 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 connection.
Considering design features 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 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 the external environment to adversely affect the 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 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 the 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 IFS 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.
In electrical tests, insulating flanges are tested both wet and dry special device- megger. 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.
An insulating flange joint (IFS) is an element of a pipeline system that is used to protect pipelines from electrochemical corrosion.
Insulating flange connections (IFS) provide electrical isolation of one section of the pipeline from another. This is necessary to combat electrochemical corrosion - a process that leads to accelerated destruction metal parts. In most cases, IFS is placed at pipeline crossings from an underground or underwater section to an aboveground one. This is due to the fact that it is the underground part of the pipeline that is affected by stray currents, leading to electrochemical corrosion. The working medium transported through insulating flange connections are dielectric liquids and gases with an overpressure of not more than 7.0 MPa (70 kgf/cm2).
These connections consist of two or three flanges separated by dielectric spacers and dielectric bushings for electrical insulation of the studs.
Insulating flange connections from two flanges:
The IFS uses flat flanges according to GOST 12820-80, or butt-welded ones according to GOST 12821-80, with sealing surface designs 2 (with a protrusion) and 3 (with a cavity). Very common in Russia are IFS according to GOST 25660-83, used for electrochemical corrosion protection of underwater, underground and surface pipelines at a pressure of 10.0 MPa (100 kgf / m 2).
LLC Germes offers insulating flange connections of standard size: Du 25-219.
The composition of the insulating flange connections includes:
- flanges;
- insulating rings (paronite gaskets) between flanges;
- insulating bushings (installed in mounting holes);
- hairpins;
- nuts;
- washers.
The production of IFS is regulated by GOST 25660-83 "Insulating flanges for underwater pipelines at Ru 10 MPa".
Insulating rings (paronite gaskets) are coated with electrically insulating bakelite varnish to protect them from moisture saturation. Viniplast or fluoroplast can also be used for the manufacture of electrically insulating gaskets.
LLC "Germes" offers a wide range of insulating flange connections.
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Insulating flange connections (IFS) |
Insulating flange connections (IFS) P<=1,6 МПа |
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IFS 25 |
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IFS 25 |
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Welded insulating joints IS (Gas) P<=1,6 МПа |
Insulating connections - shackles |
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IS 25 |
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IS-SG Du 15 |
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Insulating connections small-sized ISM |
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ISM Du 15 |
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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 uninsulated grounded structures (gas pumping stations, oil pumping stations, water pumping stations, field communications, pipelines, 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 is prohibited due to explosion hazard.
Insulating flange connections are assembled at the factory. When assembling insulating flange joints, a clear sequence must be observed:
1. Before assembly, the sealing surfaces of the flanges are covered with an insulating varnish or a special coating (IFS according to GOST 25660-83);
2. IFS fasteners are isolated from the flanges with bushings (GOST 25660-83) or insulating gaskets;
3. To avoid distortion, the flanges are connected by successively tightening diametrically opposed studs.
According to the Rules for the Design and Safe Operation of Process Pipelines, the assembled IFS 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. 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.
In addition to IFS, Germes LLC sells welded fittings made of low-pressure polyethylene, base inlets, permanent polyethylene steel joints and other necessary products for gasification and water supply.
Check prices with managers