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Expansion Joints
1 - Expansion Joints
The elastic metal bellowed parts absorbing the heat induced expansion or contraction of pipelines conveying hot or cold fl uids or subject to drastic changes in ambient temperatures are called expansion joints. If no measures are taken against changes in size of pipelines, high pressure resulting from expansion or contraction creates problems at connection points and equipment. The most proper and affordable solutions to eliminate those problems are the metal bellow expansion joints designed to compensate different types of size chances, which do not necessitate any maintenance. In brief, assemblies comprising single or multiple bellows used to compensate the change in size and to eliminate the problems caused by it due to the heat induced expansion and contraction in pipelines, ducted air systems and tanks can be called expansion joints.
The main components of expansion joints are bellows. Produced of multi-layer stainless-steel they function as springs. Expansion joints should be designed in regard to the working conditions of the systems (temperature, pressure, amount of movement, characteristics of the fl uid, etc.) where expansion joints are needed.
Production Of Expansion Joints ?
Production Of Expansion Joints
Rectangular sheets of stainless steel are rolled along the long edge of the rectangular sheet in a tube and the tube is welded. The tube is then worked up into bellows using mechanic and hydraulic forming methods. Bellow units of expansion joins are produced from stainless steel of thickness 0,1 to 0,3 mm according to EJMA (Expansion Joint Manufacturers Association) standards. However specifi c applications can also be designed and produced using nonstandard and distinctly shaped bellows. Before the design phase all design conditions and constraints have to be determined accurately. The diameter of the pipe where the expansion joint is to be mounted, the type of fluid coming in contact with, the maximum values of pressure and temperature to occur in the pipeline, the amount of expansion at the pipeline are the most important conditions of design. In addition to these lateral or angular designs for other specific systems can also be made.
Fixed Points
Fixed Points
Main Anchors: These types of anchors are the most important ones in the pipeline, because they resist the forces acting upon them. Intermediate
Anchors: Intermediate anchors do not resist the pressure thrust. However this type of anchors withstands spring resistance of the bellows as well as the frictional forces.
Pipe Guides: Pipe guides provide the proper alignment of the expansion joint movements and prevent the bowing and buckling of the pipeline. Hence they are one of the most important components of the system. Click Here.
Guides & Anchors
Alignment Guides
Axial expansion joints are not provided with attachments to restrain pressure thrust, such as limit rods or hinges. Therefore the over-extension and distortion of expansion joints can be prevented by alignment guides under all kinds of operating conditions in a correctly designed piping system. They allow the axial movement of the pipes. The Pipe Guide Spacing Chart should be used to determine the distance between guides. For the first guide next to the expansion joint the 4D + 14D principle should be used. For more information Click Here.
Axial Types
DN 25 - DN 2400
Axial expansion joints are used to absorb the thermal expansion parallel to the axis of the straight pipelines. Long piping systems are divided into shorter expanding sections, and isolated by main anchors. Thus the movements in the individual expanding sections are absorbed by the axial expansion joints in this section. Click Here.
Lateral Types
DN 25 - DN 500
Lateral expansion joints are specific expansion joints, consisting of one or more angular expansion joints used to absorb the thermal expansion in a plane vertical to the axis. The potential expansion amount to be absorbed can be augmented by increasing the distance between the bellows. This type of expansion joints may absorb big amounts of expansions. Especially the assemblies consisting of more than one lateral expansion joints are the most effective ones to absorb big amounts of expansions. Click Here.
Angular Types
DN 25 - DN 500
Angular expansion joints are the specific ones, absorbing the thermal expansion of the pipeline by transforming them to angular movements in a plane vertical to the axis. They may absorb the movements in one or more directions (in a plane vertical to the axis of the pipe). The assemblies consisting of two or more lateral expansion joints may absorb big amounts of expansions. Click Here.
Nom. Pressure
Ap ve Af Factors
In various form in 20 °C is assigned as referance and given as the maximum pressure applicable in normal working conditions. The allowed working pressure decreases as the temperature increases. The decrement can be calculated by an (AP) factor provied in the table. Other loads should be considered while determinig the maximum working pressure. Click Here.
Pipe Expansion
Tables
The most important characteristic of an expansion joint is the required expansion amount. The system is divided into various expansion sections as the piping system is designed. The thermal expansion must be determined acc. to length of the said sections and the material used for the pipe. For more information. Click Here.
Pre-Tension
Mounting
The expansion joints always must be mounted with pre tension. The amount of pre-tension must be calculated considering the mounting temperature and a distance must remain in order to leave mounting space by adding the free length of the expansion joint. Click Here.
2 - Special Expansion Joint Types
Special Compensator Applications
District Heating Compensators
District Heating Systems
The elastic metal bellowed parts absorbing the heat induced expansion or contraction of pipelines conveying hot or cold fluids or subject to drastic changes in ambient temperatures are called district heating compensator. Click Here.
Lens Compensators
Special Applications
On special inquiries, bellow part sheet thickness of the compensators increases over 2 mm, we suggest Lens type of expansion joints. These expansion joints can be produced both stainless steel and carbon steel. For more information please consult us.
Rectangular Expansion Joints
These can absorb axial, lateral & angular movements.
In case of pipelines or connection types are rectangular, we suggest rectangular expansion joints. Please consult us for your inquiries and more information about rectangular expansion joints. Please see photos during production step. Click Here
Pressure Balanced Expansion Joints
It provides great solutions in limited fields.
Pressure balanced expansion joints are used in the piping systems where the fl ow direction occurs to change counteracting the pressure thrust and absorbing axial and lateral movements. For installation instructions and more information about pressure balanced expansion joints Click Here.
Teflon (PTFE) Expansion Joints
4 Different Types ( Clients usually ask)
PTFE compensators have 2-3-5 and 7 convolutions acc.to its type. These compensators with ptfe bellow elements can absorb movements or compressions can cause diamentional changes. For more information Click Here.
Fabric Expansion Joints
For Special Applications
The elastic metal bellowed parts absorbing the heat induced expansion or contraction of pipelines conveying hot or cold fluids or subject to drastic changes in ambient temperatures are called fabric expansion joints. These expansion joints can be used for vibrations or assembly parts which can solve problems during installation. For more information please consult us.
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3 - Expansion Joint Applications
What is axial movement ?
The movements of expansion or contraction parallel to the axis of the bellows are called axial movements. KRS-14 Axial expansion joints are used to absorb the thermal expansion parallel to the axis of the straight pipelines. Long piping systems are divided into shorter expanding sections, and isolated by main anchors. Thus the movements in the individual expanding sections are absorbed by the KRS-6 axial expansion joints in this section.
FIGURE 1: This fi gure shows the simplest and most basic application of an axial expansion joint. The sequence of installation steps to pay attention to follows:
1. Only one expansion joint may be installed between two main anchors.
2. Main anchors are located in the direction of pipeline.
3. An expansion joint is located next to each main anchor.
4. The fi rst pipe alignment guide is located within the distance of 4 pipe diameters next to the axial expansion joint.
5. The second pipe alignment guide is located within the distance of 14 pipe diameters next to the fi rst pipe alignment guide.
6. The distances between the other pipe alignment guides to be located are determined according to the Pipe Guide Spacing Chart by EJMA (Expansion Joint Manufacturers Association).
