Single Axial Tied Expansion Bellow

About Single Axial Tied Expansion Bellow

A Single Axial Tied Expansion Bellow is a type of metallic expansion joint designed to absorb axial movement ie compression or extension along the pipe axis while restraining pressure thrust using external tie rods

Components of a Single Axial Tied Expansion Bellow

Component Description

Bellows Element Corrugated metal typically stainless steel that expandscontracts along the axis to absorb movement

End Connections Welded ends or flanges used to connect the expansion joint to the piping system

Tie Rods Tie Bars One or more rods that run externally between the two ends restraining the pressure thrust and allowing only axial movement

Gusset Plates Lugs Welded to the ends of the joint to serve as anchoring points for the tie rods

NutsWashers Lock the tie rods in place and allow adjustmentpretensioning

Optional Internal Sleeve Sometimes included to reduce turbulence and protect the bellows from erosion by internal flow

Function Characteristics

Movement Type Axial only expansion and contraction along the pipe axis

ThrustRestrained Internal pressure thrust is absorbed by tie rodsnot transmitted to adjacent pipe or anchors

No Lateral or Angular Movement unless explicitly designed for limited multiaxis movement

Applications

Thermal expansion in straight pipe runs

Pump and compressor connections

Systems with welldefined anchor points and limited space

Low to mediumpressure steam gas or fluid systems

Limitations

Cannot absorb lateral or angular movement

Misalignment in installation can lead to premature failure

Tie rods must be properly aligned and tensioned to function correctly

Typical Standards Used

EJMA Expansion Joint Manufacturers Association design guidelines

ASME B313 for piping stress design

Materials often conform to ASTM standards eg A240 for SS 316L bellows