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Spiroflex d.o.o.
Ljudevita Gaja 7
35 208 Ruščica
Croatia

 

Phone: +385 35 _212420
Telefax: +385 35 _457105
e-mail: info@spiroflex.hr

 

Restrained expansion joints

Application of lateral, hinged and gimbal expansion joints

Tied expansion joints are used where the equipment and structure of pipeline systems cannot accept pressure thrust forces. For tied expansion joints it is not allowed to install them as axial bellows to absorb axial movement. In the piping systems, such as “L”, “Z” and “U” bends they accept lateral or angular movement. Expansion joints are equipped with restraints such as tie rods, hinges and gimbals. The total force acting at fix points is less for pressure thrust and the main advantage ofa tied expansion joints is that they need very light anchors and intermediate anchors.

Two hinged expansion joints assemblies in a plane

Two hinged expansion joints assemblies in a plane

A pair of hinged expansion joints is used in a plane “L” bend to absorb thermal movement in horizontal leg. The pressure thrust is restrained by the hinges and only light anchors are required.

 
Three hinged expansion joints in a plane

Three hinged expansion joints in a plane

Three hinged expansion joints system is designed to absorb thermal movement in horizontal and vertical legs. Center expansion joint B must be capable of absorbing the total of rotation of A and C. The distance L1 and L2 should be maximum possible and L3 minimum possible.

Pipe loop with three hinged expansion joints

Pipe loop with three hinged expansion joints

This system of hinged bellows assemblies in pipe loop is recommended in long pipe systems to reduce the number of expansion joints. The hinge restraints are designed to absorb pressure thrust and weight of the pipe between two hinge units. Cold pulling is recommended to increase the ability of absorbing the angle movement of hinged expansion joint.

 
Two gimbal and one hinged expansion joints in three-dimensional system

Two gimbal and one hinged expansion joints in three-dimensional system

In this application two gimbal expansion joints absorb thermal movement from horizontal legs. Hinged angular expansion joint in pair with upper gimbal expansion joint takes the vertical movement. The pressure thrust is restrained by gimbal and hinge assemblies, only light fix points are required.

Lateral expansion joint in "Z" pipeline

Lateral expansion joint in "Z" pipeline

Tied lateral expansion joint used to absorb lateral deflection in pipeline plane “Z”. The pressure thrust is restrained by two tied bars and both fix points need to be only light anchors.

 
Lateral and one hinged expansion joint in three-dimensional system

Lateral and one hinged expansion joint in three-dimensional system

Lateral and one hinged expansion joint are used to absorb thermal movement in three-dimensional system. Lateral expansion joint is used in similar way as two single hinged or gimbal expansion joints. The difference is that thermal expansion between flanges remains inside the expansion joints. Forces on anchors are reduced because the pressure thrust is restrained by tied bars and hinged assemblies.