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XP Externally Pressurized Expansion Joints

FIT, FORM and FUNCTION

Externally pressurized expansion joints are specialized components used in piping systems to accommodate axial movement resulting from thermal expansion or contraction.

Unlike traditional designs, these expansion joints place the system pressure outside the bellows, allowing for greater movement capabilities and reducing the risk of instability caused by pressure thrust. Their importance lies in their ability to safely absorb large axial movements in long, straight pipe runs, all while maintaining system integrity and minimizing maintenance needs. These characteristics make externally pressurized expansion joints essential in applications such as heating, cooling, and industrial process lines where temperature fluctuations are common and reliability is critical.

XP Expansion Joint Fit:

Bellows may be attached or linked to piping flanges, pipe, or other typicalindustrial connections.
End connections may conform to standards such as ASME B16.5, ASME B36.10, or customer designed.
Fittings may be the same at each end or different.

XP Form:

Single circular metal bellows, or 1 or more convolutions.
Typical dimensions of ½” ANSI NPS to 240” ID. Overall length may vary,
typically within the range of 6” to 30”.
Bellows may include reinforcement or controlling members
Convolutions may be U shaped or toroidal
Additional accessories may be incorporated such as drains, anchor load bearing restraints.
restraints, movement limiters, protection devices.

XP Function:

Absorbs piping (thermal) movement, primarily axial but may include small lateral and/or angular movements.
Movement amplitude varies, typically within the range of 3” to 16”.
Movement frequency may be extreme low cycle (1 per year), or high cyclic (such as vibration at 60 Hz).

Metal Bellows Catalog

Catalog

This catalog contains excellent technical references to help you understand how expansion joints work, how to apply them, and how to select the expansion joint best suited for your application.

Features

Simplest, most economical design
Accepts axial, lateral, angular movements
Versatile and common throughout all industries
Use of tie rods contain pressure thrust. Can also include hinges or gimbals

Applications

The unrestrained EJ is appropriate for any application where pressure thrust can be handled by external anchorage.

Operating Range

Full vacuum to 2000 psig depending on size
Cryogenic to 1650°F+
Sizes from 1” NPS to > 240” NPS

Materials

3XX Series Stainless Steel
Nickel Alloys
Carbon Steel
Titanium
Zirconium

Industrial Applications

District Heating and Cooling Systems: Used to absorb the thermal expansion in long pipeline runs that transport hot or chilled water between facilities.
Power Generation Plants: Employed in steam, condensate, and water transfer lines to accommodate substantial axial movements caused by temperature cycles.
Chemical Processing Facilities: Protect piping systems from thermal stresses and pressure variations while ensuring safe operation of hazardous fluid lines.
Petrochemical and Refinery Installations: Enable safe expansion and contraction in high-temperature or high-pressure pipelines.
Industrial HVAC Systems: Maintain system integrity in ventilation and air conditioning networks subject to temperature fluctuations.
Water Treatment Plants: Help manage pipe movements due to heated effluent or variable process temperatures.
Marine and Shipbuilding: Used in onboard piping systems exposed to temperature changes and axial movement constraints.
Pulp and Paper Mills: Allow for flexible thermal expansion in steam and process water lines throughout the facility.