PB Expansion Joint

Pressure Balanced Expansion Joint
  • Accepts axial, lateral and angular movements
  • Eliminates Pressure Thrust
  • Pressure balance are used when pressure thrust needs to be eliminated
  • There are two types of PB, with an elbow requires a 90 degree turn in the piping system, and inline can be put in a straight piping system
Operating range
  • Full vacuum to 2000 psig depending on size
  • Cryogenic to 1650°F+
  • Sizes from 1” NPS to > 240” NPS


  • 3XX Series Stainless Steel
  • Nickel Alloys
  • Carbon Steel
  • Titanium
  • Zirconium
  • Bellows may be a attached or linked
    to piping anges, pipe, or other typical industrial connections.
  • End connections may conform to standards such as ASME B16.5, ASME B36.10, or customer designed.
  • Fittings generally not the same at all locations: interface connections may be as noted above. Connections within the assembly are typically to pipe.
  • At least Two circular metal bellows, each with 1 or more convolutions. Can have Four bellows.
  • Typical dimensions of 2”ANSI NPS to 120” ID. Overall length may vary, typically within the range of 36” to 240”.
  • Bellows may include reinforcement or controlling members.
  • Convolutions maybe U shaped or toroidal.
  • Additional accessories maybe incorporated such as load bearing restraints, movement limiters, protection devices.
  • Absorbs movement, primarily axial, but may include small amounts of lateral and/or angular movement.
  • Use of controlling members, typically tie rods, is required to cancel the bellows pressure thrust forces on adjacent equipment/piping.
    (some mes referred to as PA loads).
  • Movement amplitude varies, typically within the range of 1/4” to 10”.
  • Movement frequency may be extreme low cycle (1 per year), or high cyclic (such as vibration at 60 Hz)