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