Machinery

The bellows compensator: varieties and main characteristics

April 2, 2020

The bellows compensator is a device in the form of a flexible insert element, which is used in various pipeline designs. This product performs a very important function - to compensate for changes in the length of sections of a communication. The length of the pipes changes, usually, due to temperature effects or due to installation work.

In all types of pipelines, in which there is a risk of thermal expansion, compensators are installed

Bellows expansion joints - what is it?

Today bellows expansion joints are used in various fields of human activity. Among the main such industries can be noted:

  • energy industry;
  • metallurgical sphere;
  • oil refining;
  • as well as utilities.

Such devices are very important components of various communications and are used almost everywhere, where it is necessary to compensate for the thermal expansion of the pipeline. Steel pipes have the lowest coefficient of thermal expansion, and the largest - polyethylene products. Compensator for polyethylene pipes is a necessary measure to prevent deformation. It is worth noting, that bellows expansion joints for polyethylene pipes are connected to the communication by means of flanges. In addition to its main task, bellows expansion joints perform several other important functions:

  • protection of the pipeline from mechanical damage, which can lead to deformation of pipes and their destruction;
  • compensation of shortcomings, which could be during the laying of communications. Usually, due to such mounting errors, individual sections of the pipeline are not on the same line with other sections of communication;

Useful Information! Bellows expansion joints can also act as an adapter. In this case, they are used to connect pipes with different cross-sectional indicators.

  • vibration damping, which arise in communication when moving the working environment. And also worth noting, that vibrations in the system are formed not only from the movement of the medium through the pipes, but also from the work of various equipment;
  • ensuring the required indicator of tightness in transport pipeline structures.

Bellows expansion joints are universal devices and can perform several functions simultaneously

Technology of manufacturing bellows expansion joints

The most important part of the design of such a device is a bellows. Bellows corrugated tube is made, usually, stainless steel.

Stainless steel is a reliable material, which has high strength characteristics, as well as the following benefits:

  • resistance to harmful corrosion;
  • resistance to aggressive chemicals;
  • resistance to temperature changes;
  • environmental friendliness;
  • aesthetics (does not require additional paint treatment);
  • durability.

The process of production of bellows corrugated pipes is performed in two main stages:

  1. Steel thin-walled sheets are welded longitudinally by means of welding equipment, resulting in a cylinder.
  2. A ribbed surface is formed on the obtained cylinder. So, corrugation is performed.

To achieve maximum flexibility bellows, bellows walls are multilayered. Due to such manipulations the finished product is highly resistant to pressure, but at the same time remains quite flexible.

Compensators are made of high-strength steel and have high resistance to high pressure

All auxiliary parts of bellows expansion joints are made of high-strength carbon steel and have high technical characteristics..

The principle of operation of the bellows compensator

To understand that, how exactly the bellows compensator works, you need to learn one important point. Ambient temperature, transported in communication, usually, has a clearly defined indicator, while the ambient temperature cannot be stable.

Importantly! At low ambient temperatures, the pipeline, consisting of metal, compresses and shortens, and at high temperatures, vice versa, expanding.

The processes of compression and expansion adversely affect communication. Ultimately, a change in the length of the pipeline structure can lead to the loss of the required sealing performance at the joints of the pipes. To avoid such negative consequences, use special bellows compensators, which neutralize deformation influences and do not allow the pipeline to lose the operational qualities.

The principle of operation of this device is based on that, that all the extra effort, which appear when expanding or narrowing other areas of communication, are not transferred further by the pipeline. This additional effort is assumed by the bellows compensator. Due to this, the deformation can affect only certain areas and is not transmitted further through the system. The same can be said about vibrations inside the system. Such products have high elasticity. To date, several modifications of bellows compensating elements.

At temperature expansion of pipes the compensator accepts all loading, preventing deformation and destruction of the pipeline

As the ambient temperature rises, the pipeline expands in two planes: horizontal and vertical. Therefore at installation it is necessary to fix correctly sliding and static sites of system.

Varieties of bellows expansion joints

Today on sale you can find several modifications of this device. The required type of bellows expansion joint is selected depending on operating conditions, namely - the type of load, which will need to be stabilized. Consider the main types of bellows models:

  • compensator bellows-sealed axial under welding (SWR);
  • bellows flange compensator (KSF);
  • corner;
  • cardanic.
  • sliding.
  • start.

Axial. It is mounted on a direct section of communication between two static supports. Such supports can be of two types:

  • intermediate;
  • final.

This compensator is used to stabilize the deformation effects in the axial direction. It should be noted, what are welded models, in addition to flexibility, have high strength characteristics.

Consider the most common mistakes when installing an axial compensator for welding:

  • Failure to install may be due to non-compliance with the installation instructions;
  • application of bellows axial compensator for welding in conditions, when two pipes are in a state of misalignment in relation to each other;
  • getting foreign elements into the inter-corrugated space;
  • guide supports, made of low quality material, which contribute to subsidence of the soil, resulting in axial shifts between the pipes;
  • use of KSN in communication, transports the environment with the raised maintenance of chlorides. This leads to corrosion of the bellows.

Compensators are available with different types of attachment to the pipes, one of the main models is axial, is mounted by welding

If you consider all the above rules, then axial bellows (interstitial) the compensator will last long enough, effectively coping with the tasks assigned to him.

Flantseve. This model is one of the most common. It is used everywhere and is different, that for connection with a pipe has special connecting elements - flanges. CSF is used to stabilize loads in the axial direction.

Useful Information! It should be noted, that such compensators differ in excellent heat resistance and can be mounted on communications, the temperature of the medium which reaches 250 ° C.

Compensator bellows axial flange. Is a reliable product, which protects pipes from static, as well as dynamic loads. CSF is an indeterminate compound, which stabilizes thermal changes in the length of communication.

Corner. Such models are used to connect communication at turns. This connection can be made at different angles. Angular rotary compensators are designed to stabilize the effort, arising on turns of a pipeline design.

These models, usually, are equipped with a special hinged element, which determines the nature of the movement of the device. The angular model can move only in one plane, excluding axial movements. Thanks to the hinged element, the bellows is also protected from twisting.

Cardan. Unlike the previous model, this device can move in any plane. It is also worth noting, that the gimbal model is equipped with two hinged parts. This design allows it to bend in the axial direction.

Cardan-type compensators allow to compensate for angular displacements in pipeline systems

Sliding. This compensator is mounted at communication points, where effort may arise, which will entail a mutual shift of individual segments of the pipeline structure. One of the most common options for using this model is to install it at the point of entry of communications into the building. In this case, when the structure subsides, the compensator will protect the pipe from deformation and prevent an emergency. exept this, shear device is used to stabilize the shortcomings, committed during the communication. Sliding models, usually, have two bellows, therefore, they are also called two-section bellows expansion joints.

Compensator starting bellows-sealed. According to its design, it is included in the axial model, however, has one difference - it is made with a protective cover, which consists of two parts.

Bellows compensating device (SKU)

Bellows compensator UWC is made of stainless steel and can be of two types depending on design features:

  • one-section;
  • two-section.

Bellows compensating devices are equipped with a special protective case, which protects the bellows from mechanical deformations, and also contributes to the alignment of the device.

Such a device, usually, insulated with a special material - polyurethane foam (PPU). PPU insulation is a reliable and modern option for insulation. And also worth noting, that in addition to thermal insulation, The UWC is also equipped with waterproofing. There are two options for waterproofing bellows compensation device:

  • waterproofing with polyethylene;
  • galvanized steel waterproofing.

pay attention! Models with galvanized waterproofing are used in communications, laid in an open way (on the surface of the earth). And compensatory devices with a waterproofing from polyethylene are operated at the closed installation of communications (underground).

Consider the main benefits of using a UWC:

  • such a device does not require preventive examinations;
  • such products, usually, have the same service life, as well as in communication in PPU of thermal insulation;
  • The UWC can be installed at almost any point of communication, however, it is worth noting, that when choosing the location of such a device, it is desirable to provide for the possibility of shifting the protective case over its entire length.

When the UWC is installed open, a protective box must be installed, which will protect the compensator from access by third parties, and also protect the device from precipitation.