Axial Metal Expansion Joints

                  In Pipeline systems, such as the ones in Pharmaceutical, Chemical, Power, Glass, Petrochemicals, Oil and Gas, and Steel Industries, expansion and contraction of metal takes place, with variations in temperature. With this expansion and contraction of metal, there is variations in movement of the individual sections of the pipes.
                  If the movement cannot be absorbed by the piping system, then metal expansion joints are used to compensate the movements that occur. Apart from the thermal movement, other applications such as vibrations and noise in pumps, compensator, turbines, motors and vessels is also compensated by using metal expansion joints.
                  Depending upon the nature of movement that needs to be compensated ( axial, lateral or angular ), expansion joints are designed. Ocelflex’s Metal Expansion Joints are designed to absorb the movement, as well as withstand other operating conditions such as ,i>temperature, pressure and the inner media. Our design is in accordance with international standards such as E.J.M.A. and A.S.M.E..
Single Circular Metal Expansion Joint / Expansion Bellow
                  Single Axial Expansion Joints consists of a single circular metallic bellow welded to end connections. The expansion bellow can absorb all three movements – axial, lateral and angular. Since it is capable of carrying all the three movements, it is necessary that the piping be controlled/guided as to the direction of movements required by the applications.

                  Even though a single circular expansion joint can absorb all the three movements, it is more capable of absorbing movement in the axial directions and less in the lateral or angular directions.

                  This simple circular expansion joint, also known as Single Axial Expansion Joint, is used in applications which require minor movements, such as vibrations or thermal fluctuations, applications such as in pumps and compressors, boilers, engines and pressure vessels.

                  The metal expansion joint cannot resist any deflections with force except the resistance of the metal expansion bellows, which is a function of the spring rate times the deflection amount.

                  Optional Stainless Steel Covers or Inner Sleeve ( Inner Liners ) are available on request. It is recommended to use inner sleeve in applications where there are high frequency vibrations caused by the inner media flow or where the inner media is corrosive enough to damage the inner thin wall of the metal expansion bellow.

  • ⇨ Bellow Inner Diameter : DN 40 to DN 5000 ( 40 NB to 5000 NB, 40 mm to 5 mtrs)
  • ⇨ Bellow Length : 4" to 20" Long ( 100 mm to 450 mm ). Also available as per your specification
  • ⇨ Design Standard : Bellow : E.J.M.A. 9, A.S.M.E., End Fittings : Custom Made or Standardized
  • ⇨ Pressure & Temperature : Temperature : upto 700 C, Pressure : upto 30 Kg/cm2
  • ⇨ Additional Accessories : Lugs and Tied Rods, Inner Sleeve, External Protective Cover
  • ⇨ Bellow Material : Stainless Steel 300 Class ( AISI 304, AISI 316, AISI 321, AISI 316L, AISI 304L), Inconel.
  • ⇨ Inspection Documentation : Leakage Test Reports, Specification Inspection Report, Material Test Report.
Material & Standard
Fill Specification Sheet
Technical Details
Tied Circular Metal Expansion Joint / Expansion Bellow
                  Metal Expansion Joints are available as tied or untied type. Single Axial Tied Metal Expansion Joints are Axial Expansion Joint where the end connections is welded to tie rods using lugs, which are capable to carry the pressure thrust of the system, to provide protection in case of failure in the main anchors.

                  Tie Rods are usually in the form of threaded rods, attached to the Metal Expansion Joint Assembly, fitted to metal lugs / ears using nuts, so as to restrict the movement of bellows above the specified range ( axial, lateral, angular ) during normal operation.

                  In case of some failure, or some unexpected movement, the limit rods also designed to prevent the over extension or over compression of the metal expansion joints. However, in any case, the Tied Rods are not designed to absorb the internal pressure. These are more appropriately known as limit rods, since it limits the movement of an expansion bellow.

                  Tied Rods are generally threaded and composed of Mild Steel, with nuts on either sides, adjusted to the specifications of the expansion joint, as per the movement required by an application.

                  If two tie rods are placed 90 degree opposite to the direction of rotation, then angular movement can be accommodated. These are also suitable for small amounts of lateral movements.
Types of End Fittings for Axial Metal Expansion Joints / Expansion Bellows

Axial Metal Expansion Joint with
Fixed Flanged End

-  Either side the flange is welded to the Metal Expansion Bellow
-  Common flange Standards: BS – A Table, E table, F table, PN 16, PN 10, PN 25, ASA 150
-  Care should be taken to avoid torque during installation of the expansion joint
-  Manufactured either in tied or untied type metal expansion joints
-  Material: Mild Steel, Stainless Steel, or as per application required.

Axial Metal Expansion Joint with
Pipe / Weld End

-  Pipe ends can be either plain weldable pipe or with threading.
-  The expansion joint is welded to a pipe end, which can be used onsite to be welded to the application part.
-  Weldable end make the expansion joint installation easier.
-  Manufactured either in tied or untied type metal expansion joints
-  End Fitting can be either Mild Steel, Stainless Steel, or as per application.

Axial Metal Expansion Joint with
Loose / Rotating Flanged End

-  Also known as Van Stone Metal Expansion Joints.
-  The flanges are kept loose / rotating, over the metal expansion bellow making installation easier.
-  Manufactured either in tied or untied type axial metal expansion bellows.
-  End Fitting can be either Mild Steel, Stainless Steel, or as per application required.

Axial Metal Expansion Joint with
Vacuum Flange End

Types of Metal Expansion Joints / Expansion Bellows

                   Depending upon the nature of movement, and upon the piping system where the expansion joint has to be installed, there are different types of Metal Expansion Joints. Review the metal expansion joints below to choose the optimal design for your applications. Click on any to understand how the expansion joint works :

Understanding Expansion Joints Terminology & Definitions
                   Many parameters are to be considered to design an expansion joint. To understand these and other expansion joint terminology, refer the below links.
                   Depending upon your application and requirement, you can fill out the metal expansion joint specification sheet for us to understand your enquiry, and based on our experience we shall quote the most suitable metal expansion joint for your application, at the most competitive rates. In case you already have a sample, and would like us to manufacture a similar product, then you can send us the photographs, dimensions and/or drawings.

  • Expansion Bellows, Expansion Joints, Pressure & Temperature Parameters
  • Inner Sleeve, Multi Ply, No. of Convolutions, Material of Construction
  • Axial, Lateral and Angular Movement
  • Pipe Guides and Anchoring, End Fittings / Connections & Standards
  • E.J.M.A. standard and other designs