METAL HOSE & BELLOWS - Formely Hydraquip Metal Hose
PLUMBING & COOLING - Formely Hydraquip Braided Hose



Design Pressure

16 Bar

Operating Temperature



Hydraflex`s GB.FS type angular expansion joints are designed to permit angular rotation in any plane by the use of two pairs of hinges affixed to a common floating gimbal ring. The gimbal ring, hinges and pins are designed to restrain the thrust of the Expansion Joint due to pressure and extraneous forces, where applicable.

Integrated liners minimize contact between the inner surface of the bellows and the fluid to hold friction losses and provide a smooth flow. Stainless steel bellows (membranes) are designed according to EJMA coding system and manufactured acc. to European Standard EN 14917:A1.

GB.FS type expansion joints are finished with Nickel plated carbon steel, oval flanges (EN:1092/1-PN16 or BS4504-PN16). Stainless steel flanged version provides high corrosion and temperature resistance up to 550°C. Van stone end configuration for swivel flanges provides complete stainless steel surface which is in contact with the fluid.


    • All GB.FS type expansion joints are produced by fully penetrated TIG welding method acc. to Hydraflex’s approved WPSs.
    • Design GB.FS is type approved by hydrostatic pressure test @1.5 times of the design pressure.
    • PED 2014/68/EU approval and material certificates acc. to EN 10204 is available for all sizes on request.


    • Building services, HVAC-R piping systems
    • Pump connections, vibration producing systems
    • Industrial process & applications
      Steam & condensate pipelines


    • Gimbal hardware is an indicator attached to the hinge pin with an angular scale attached to the hinge arm. This allows one to quickly determine the extent of angular offset.
    • Minimum application area in comparison with pipe loops.
    • Long service life, easy installation and maintenance free design.


We strongly advise not to use expansion joints to handle the piping misalignments. Torsion on bellow parts is not desirable and should be eliminated.



    • Store in clean dry area where it will not be exposed to heavy traffic or damaging environment.
    • Care shall be exercised to prevent any damage to the thin bellows section, such as dents, scores, arc strikes and weld splatter.
    • No movement of the Expansion Joint (compression, extension, lateral offset, rotation) due to piping misalignment shall be imposed.
    • Any field pre-positioning shall be performed in accordance with specific instructions which include both the direction and magnitude of movement.
    • It is good practice to leave one flange loose until the expansion joint has been fitted into position. Make necessary adjustment of loose flange before welding.
    • Anchors, guides, and pipe supports shall be installed in strict accordance with the piping system drawings.
    • The Expansion Joint, if provided with internal sleeves, shall be installed with the proper orientation with respect to flow direction.
    • Once the pipeline anchors or other fixed points are in place, the piping is properly supported and guided and the Expansion Joint installed, the shipping devices should be removed in order to allow the Expansion Joint to compensate for changes in ambient temperature during the remainder of the construction phase.
    • Do not use chains or any lifting device directly on the bellows or bellows cover.
    • Do not force-rotate one end of an expansion joint for alignment of bolt holes. Ordinary bellows are not capable of absorbing torque.
    • Do not use cleaning agents that contain chlorides.
    • Do not use steel wool or wire brushes on bellows.


No more than only one expansion joint must be installed between two main anchors. If the thermal expansion of the pipeline is too big to be handled by single expansion joint, pipeline should be divided in sections by additional intermediate anchors.


If possible, expansion joints are advised to be located as close as possible to one of the anchors to prevent buckling risk.  Hydraflex, Spring Lane, Northampton NN1 2JW  Sliding guides & anchor allocations should be completed as shown below, L4 &L5 values should be selected from the 


The attachment edges of the pipe should be smooth, clean and parallel to each other. Don`t use bellows to correct for misalignment of piping unless this has been considered in the
design of the expansion joint.

Counter flanges should be placed vertically to the pipe axis.
Using the proper electrode, weld the expansion joint to adjacent piping. Damages caused by arc sparks through welding process should be prevented. Bellows must be protected by a wet towel or cloth during the welding
Orient expansion joint flanges so that the bolt holes are aligned with the mating flanges
Do not torque the expansion joint to match the bolt holes of the mating flange. This causes torsion on the bellows and will severely reduce the bellows capability during operation and may lead to premature failure of the expansion joint.


Restrained expansion joints; i.e. angular and lateral expansion joints, are able to absorb angular rotation or lateral deflexion which is perpendicular to the centreline. They are equipped with restraining parts (hard ware) that can absorb the pressure thrust and additional loads that may occur in the pipe system. This type of expansion joints absorb the thrust loads caused by internal pressure, So piping engineers do not have to include this force while calculating the anchor loads.

Both types of expansion joints require a pipe run with changes in direction. The different possibilities of compensation systems are explained below.


If you are working with the installation of unrestrained expansion joints with no built-in restraining hardware like tie rods, hinges gimbals etc... Fixed points should be created as to withstand springing force and the pressure thrust. We strongly advise not to use of expansion joints to handle the piping misalignments.

Pressure thrust is the most important force encountered in pressurised pipe systems and if ignored or incorrectly calculated, it can have a major impact on the pipe systems and the anchors. Pressure thrust can`t be eliminated as long as the axial bellows movement exist in the pipeline, and it must be calculated very carefully. Bellows usually have a cross-sectional area, which is slightly larger than the pipe diameter due to the height of the convolutions.

Fp = P x A
Fp = Pressure thrust force [N]
P = Pressure [bar]
A = Bellows mean diameter area [mm2]

Flexible bellows can be compared to a steel spring in its flexible motion. The spring rate is an expression of the force required to compress
or extend the bellows, or alternately its resistance to deflect, which is another factor to take into account when calculating loads on fix points.
The amount of the spring force is dependent on the bellows spring rate and the amount of the bellows movement, which is calculated as follows:

Two gimbal and one hinge angular expansion joint
in a three‐dimensional system

F = K x X
F = Force [N]
K = Spring rate [N/mm]
X = Movement [mm]


If you are working with the installation of unrestrained expansion joints with no built-in restraining hardware like tie rods, hinges gimbals etc... Fixed points should be created as to withstand springing force and the pressure thrust. We strongly advise not to use of expansion joints to handle the piping misalignments.


A careful inspection of the entire piping system shall be made with particular emphasis on the following:

    • Are anchors, guides and supports installed in accordance with the system drawings?
    • Is the proper Expansion Joint in the proper location?
    • Are the Expansion Joint flow direction and pre-positioning correct?
    • Have all of the Expansion Joint shipping devices been removed?
    • If the system has been designed for a gas, and is to be tested with water, has provision been made for proper support of the additional dead weight load on the piping and Expansion Joint? Some water may remain in the bellows convolutions after the test. If this is detrimental to the bellows or system operation, means shall be provided to remove such water.
    • Are all guides, pipe supports and the Expansion Joints free to permit pipe movement?
    • Has Expansion Joint been damaged during handling and installation?
    • Is Expansion Joint misaligned? This can be determined by measuring the joint overall length, inspection of the convolution geometry, and checking clearances at critical points on the Expansion Joint and at other points in the system.
    • Are the bellows and other movable portions of the Expansion Joint free of foreign material


For any more information that you may require then please contact one of our team. 

Northampton: 01604621964  Bolton: 01204529536  Rugby: 01604621964

Email: [email protected]

Technical Info

UNIT C, Spring Lane, Northampton, NN1 2JW

+44 (0)1604 621 964
[email protected]


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