What is flanged connections?

often used in industry flanged connections.They should ensure integrity and durability of assembled structures.The role of secure connections is important, because the fragile bond can lead to large losses and threaten the health of service personnel.The main element is a flange connection.This component is a metal disk and provides a strong and tight plug connection.His use of a flange found in the industry pipeline transportation, utilities.Through the use of different materials for its production, it becomes almost universal element of pipeline construction.

Types of flanges

for technological pipelines developed a large number of constructions of this part.All flanges consist of the following elements - the flanges, gaskets, fasteners.The main task, which is assigned to this node - the union of the parts of the pipe or pipe connection to additional equipment.The flanges are divided into types depending on various parameters.By design, they are divided into:

• whole;
• free.

difference is that the entire flange with the housing, respectively, undergo the same load.They are produced together with the reinforcement during casting or forging, and the combination can be made by welding.As for free, they are a drive that is attached to a welded flange or the flanged edge of the pipe.In both species, there are both disadvantages and advantages.Loose flanges are easy to assemble, their design makes it easy to combine holes for studs.The disadvantage is a reduction in strength and stiffness than solid flanges.

Separation flanges intended:

• For valves and pipelines.Flanged pipe connections of this type are used for all kinds of pipe and industries, transport, housing and communal services.
• for vessels and apparatuses, such compounds are used for the distillation of crude oil, heating systems, equipment and containers for the reservation.

Standards

All flanges are divided into several types according to GOST and execution:

1. alloy flanges are made integral with the body.They can be cast from steel or iron.
2. steel flanges, which are threaded on the neck.This type has a rather limited use and is mainly used for low pressure conduits.
3. Collar flanges.They are a product made of steel, which is obtained by butt welding.Appointment of collar flange is connected by pipelines with high and medium pressure.The advantage of this type lies in the simplicity and mounting economy.Compared with the flat flanges welded, we consider the following paragraph, they reduce the complexity of manufacturing an average of 20% and the amount of work on welding two times.
4. flat flanges welded.They are made of steel and are used for flanged connections of industrial pipelines.
5. loose flange.This species has its own characteristics and is subdivided into three subspecies:

• to shoulder, they are used for pipes with aggressive media, against which the shoulder prevents the flange itself;
• on flanged pipe;
• on the welded ring, they are used for pipes of non-ferrous metals - copper and its alloys, aluminum and stainless steel;

Selection and connection

1. form flange connection.Flanges can be: round, oval or rectangular.
2. Orifice.Its size corresponds to the internal cross-section of the flange, which will take place on Wednesday.
3. Design.This parameter regulates the flanges GOST 12815-80 includes 9 different categories of performance.
4. pressure.The compounds can withstand the maximum nominal pressure, it depends on the performance and the geometric dimensions of the flange.This option also provides a basic regulatory document.
5. material.For making use cast iron, carbon, alloy, stainless steel.The material is selected in accordance with the use environment of use.It may also be employed and expensive metals.

electrically insulating compound

flange connection has a number of differences from other species, and bears the task obstructed electric current, as well as protection against galvanic corrosion.Most pipelines are laid underground where possible the risk of stray currents.In general, they do not carry the danger around the pipe at the entrance, but it is very dangerous to the point where they exit.Such exposure can lead to the destruction of the metal, cracking and leakage of the fluid or gas, insulating flange connection provides the necessary security.It consists of flanges, special insulated spacers, bushings and fasteners.Apply such a connection in the following cases:

• on the border of the pipeline and its transition from the supplier to the consumer;
• when flanged pipe provides the combination of different materials from which they are made;
• on the pipelines, which are laid in the sources of stray currents;
• output insulated pipe network, which is connected to uninsulated pipe;
• on land plots distribution stations.

Other types of flange connections

• Measuring flange connections. They provide docking pipeline networks with additional equipment and measuring devices.
• connections working under great pressure. Such components are subject to variable loads from the working mechanisms.Therefore, to ensure that the density and strength, and durability, must comply with a number of technological nuances installation.Tightening stud gradually made circular and in sequence.Flanged joints can become stronger by use of a lens type gasket.To use this kind of gasket, you first need to polish the surface and gaskets and pipe itself.The best option for this type are threaded flanges.It may also be used along with a lens pad, flat metal.
  maximum density flange connection is provided using such materials for flat gaskets such as copper or aluminum.

• locking flange. The compound of structure fully complies with the flange, the difference lies in the fact that instead of the usual fasteners - bolts and studs, a special design of the strip, which compresses the flange and tighten the bolts.In such compounds, the hole diameter of the flanges are absent.This kind of well-established himself in the nodes that require rapid and periodic disconnection connection.Use in this case can be welded flat flanges or butt welded.

Flange fasteners

for mounting flanges definitely needs fixing.For fixing pipes used such fasteners: screw, nut, bolt and washer.Since flanged pipe connections - it is a responsible design fasteners to bring a claim in accordance with the following parameters:

1. Wednesday.It can be an aggressive or not.Based on this parameter, the environment, selected fixture.For aggressive media, preference is given to steel with anti-corrosion properties.It is also possible to use special coatings to prevent corrosion.
2. temperature.It plays the role of the temperature of the liquid or gas to be transported through this pipeline and temperature conditions of the environment.Each material has a working temperature range, whereby the selected product.If the environment does not exceed -30 ° C, it is possible the use of conventional steel grades, lower temperatures are used cold-mark.
3. pressure.The higher the operating pressure, the higher the parameters should have the material used, of which the studs for flanged joints.
4. Indicators fasteners: type of thread, step length.
5. material.Steel, which is used in the production of fasteners for flange connections can be classified into four categories:

• carbon steel of general purpose, operating temperature should not exceed the value of 200 ° C and a maximum diameter - 48 mm;
• carbon steels used for the manufacturing of high accuracy, operating temperature can not be above 300 ° C;
• carbon steel with high quality fasteners made of this material can be used at temperatures above 450 ° C;
• alloy steels, which have thermally stable and corrosion protection.

limited use of fasteners

Choice fasteners due to the above parameters, but there are some limitations:

1. Clamps operated at a working pressure of 25 kgf / cm, limited to choosing the type of product.As for the pressure that exceeds this figure may be used only studs for flanged connections, the use of bolts is prohibited.
2. Steel grade for a couple of "stud-nut" can be selected as the same and different.If one material is used, the strength of the nut must be lower than the strength of the stud 20 units.

There is a special guest studs for flanged connections, according to which the selected nominal size fastener.Sizing depends on the operating pressure, which will be subject to a stud.

Gaskets

This item is part of an isolated flange connection, in order to provide the required density between the flanges.Gaskets are divided into different types according to certain parameters.Depending on the material from which they are made are distinguished categories:

• metal;
• non-metallic;
• combined.

distribution of elastic pads:

• elastic;
• hard.

This property determines the material of which the gasket for flanged connections.Elastic obtained from the combined and non-metallic species.Hard pads are basically metal and non-metal produced from materials such as fiber, hard rubber, Paronite, and so on. D.

Features pads

On this basis gaskets for flange connections are divided into:

• Flat(can be either metallic, nonmetallic and combined) and their use in joints with flat surfaces.Inner diameter of flat gaskets must be greater than the pipe diameter of 1-3 mm.
• Lens gasket made of carbon and alloy steels, they can be both rigid and elastic.
• Oval provides a reliable seal, while the load on the bolts quite moderate.Contact cushioning product occurs at the outer and inner circumferential flange.The material for these pads is a carbon steel or stainless steel.
• Corrugated gaskets can be either metallic or non-metallic.They are made of a thin sheet of copper, mild steel as a non-metallic material used is asbestos paper or paperboard.The inner diameter corresponds to the flange and the outer bolts adjusted location.
• Spiral are elastic gaskets.Such a gasket is composed of three elements - the scroll portion and two rings restrictive.
• Gear gasket material for these pads is mild or stainless steel.Isolated flange connection with this type of gasket can be operated at temperatures not exceeding 480 ° C.

calculation flanges

Once the flange type, depending on its destination, the type of cushioning products, as well as the materials from which the product is manufactured, designers select the required dimensions of the part of the special tables.They are presented in their respective guests.Although the flanges are standard items, very often there is a need for designing an individual product.The system of calculation includes the following items:

1. Calculation of plastic deformation at the base of bushes, it relates to compounds of working at low temperatures and pressures.
2. Accounting external bending moment, appearing on the load on the bolts.This parameter determines the strength properties of the flange.
3. Calculation of the stresses, especially for products that are produced by welding.
4. Selecting step bolts, incorrect identification of this parameter may cause deflection rings between flange bolts.

calculation of flanged joints should take into account a variety of loads.There are two options - in the first case, the load on the bolt is transmitted to the lining, the second - is an even distribution of load between the gasket and the support ring.