Definition of Movement & Construction

Axial Compression

Reduction of face-to-face dimension measured along the axis.


Axial Elongation

Increase of face-to-face dimension measured along the axis.


Transverse or Lateral Movement

The movement of the joint perpendicular to the axis.


Angular Movement

The displacement of the longitudinal axis of the joint from its initial straight line position (a combination of axial elongation and axial compression)

See section on this site entitled "Additional Considerations for PTFE Style Expansion Joints" regarding damage which can result if they are removed. Rotation (or "torsion") about the longitudinal axis of an expansion joint is prohibited and can lead to premature failure and/or rupture of the unit and may result in property damage, serious personal injury, or death.

Use of these units either when improperly installed or beyond the Pressure/Temperature Rating or vacuum Rating may cause premature failure and/or rupture of the Unit and may result in property damage, serious personal injury, or death. Safety sheilds must be used in hazardous service.

If components show significant deterioration due to abrasion, damage, or corrosion, the assembly should be removed from service. Failure to periodically perform inspection for abrasion, damage, or corrosion may lead to failure and/or rupture of the assembly resulting in property damage, serious personal injury, or death.

Do not install nuts or connecting bolt heads behind expansion joint flanges or accidental wrench damage may occur to the PTFE element. Do not drill out threads.
An internal sleeve should be used where abrasive slurries or solids are or may be present.

Flexibility is the Key to our Success

UNAFLEX® offers the greatest variety of Expansion Joints available to industry. Extensive inventory of standard products as represented on this web site to custom variations of almost any configuration imaginable, are capabilities we pride ourselves on!

Tapered Joints

Tapered joints are used to connect pipelines of unequal diameter. They may be manufactured as concentric or eccentric, depending upon pipe alignment.

Tapered Joints

Offset Joints

Offset joints are used to correct initial misalignment greater than 1/8 inch. Drawings must accompany orders with inquiries for offset joints.

Offset Joint

Sleeve-Type Joints

This type of joint is constructed as a standard spool-type joint minus the integral flanges. The I.D. of the sleeve end is the same as the O.D. of the pipe.

Sleeve Type

Filled Arches

Filled arches are built as an integral part of the carcass. Their function is to reduce turbulence and prevent the collection of sediment in the archway. Although they are of low durometer filler stock, movement of the joint is reduced approximately 50%.

Filled Arches

Multiple Arches

The purpose of additional arches is to increase movement to the joint. Movement of a multiple arch joint can be calculated by multiplying the movement of a single arch joint by the number of arches.

Multiple Arches


Rectangular or square expansion joints are available in light-weight ducting constructions to heavy duty styles for connection between turbine and condensers.


No Arch

These joints are available for applications where vibration or sound is a factor, but movement is not.

No Arch

Wide Arch

This type of joint is available when the greatest amount of movement in the shortest possible space is required. Wide arch constructions are available with all the above mentioned variations.

Wide Arch

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