June — 2013 — The Expansion Joints Blog


Archive for June, 2013

Externally Pressurized Expansion Joints

June 30th, 2013 Comments off

Externally pressurized expansion joints are suited for piping systems that require large amounts of axial compression or extension. In externally pressurized expansion joints, the bellows elements are arranged so that the media flow is on the external surface of the bellows. Externally pressurizing the bellows eliminates pressure instability as a limitation to the design and permits the absorption of large amounts of axial expansion.

Typical movement conditions that occur in a piping system:

  • Installation: allow one cycle for installation misalignment
  • Start-up / Shut down: movements produced between the minimum ambient temperature and the maximum start-up temperature. This is normally a very low number of cycles.
  • Operating: movements produced due to temperature fluctuations during system operation. This is typically a very small movement for a very large number of cycles.
  • Excursion: movement resulting from a worst case / upset scenario, occurring during system operation. This is normally a very low number of cycles.

U.S. Bellows externally pressurized expansion joints are designed for 1000 cycles for any one tabulated movement shown. Movement may be increased, decreasing the cycle life, by using the graph below. This graph may also be used for superimposing more than one movement condition on the bellows at one time.

Cycle Life / Movement Conversion GraphRead more about Externally Pressurized Expansion Joints


59″ Dia. Single Hinged Expansion Joint Refurbished in Two Weeks

June 3rd, 2013 Comments off

59" Dia. Single Hinged Expansion Joint Refurbished in Two Weeks

Within a two week deadline, U.S. Bellows refurbished a 59-1/4″ diameter single hinged expansion joint for a refinery in Louisiana. The expansion joint is 119-3/4″ in overall length and designed for .82″ angular rotation at 1380°F and 35 psig. The bellows are fabricated from Inconel 625 LCF, and the entire assembly is 304H stainless steel. Before shipment, the bellows were x-rayed and the assembly was 100% dye penetrant and air tested to 52 psig.


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