Externally Pressurized Expansion Joints — The Expansion Joints Blog
Home > Externally Pressurized Expansion Joints > Externally Pressurized Expansion Joints

Externally Pressurized Expansion Joints

December 7th, 2010

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.

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.

Bellows Cycle Life / Movement Conversion Graph

Using the graph: example: 2500 cycles reads C.F. of 1.23

  • Enter the graph horizontally at the number of anticipated cycles or the movement condition being considered
  • Move vertically until the graph I intercepted
  • Move horizontally and read conversion factor

Fourteen Externally Pressurized Expansion Joints Designed for NASA

Fourteen Externally Pressurized Expansion Joints Designed for NASA

  • 4″ to 14″ diameter range
  • 21″ to 42″ O.A.L. range
  • 304 stainless steel bellows
  • 300 lb. carbon steel flanges
  • Design conditions: 200 PSIG at 500ºF
  • Internal guide rings serve as limit stops
  • 100% dye-penetrant examined
  • Hydrostatically tested

Externally Pressurized Expansion Joints for a Steam Plant in Kent, Ohio

Externally Pressurized Expansion Joints for a Steam Plant in Kent, Ohio

  • 10″ to 24″ diameter range
  • 304 stainless steel bellows
  • Carbon steel shell and flanges
  • Design conditions: 150 PSIG at 350ºF
  • Maximum of 4″ compression
  • Hydrostatically tested
Comments are closed.
border

Contact Us: +1 (281) 241-9418 Toll Free: (855) 591-0906 Fax: +1 (713) 731-8640 sales@usbellows.com
Our Parent Company: Piping Technology Pipe Supports, Pipe Clamps, Pipe Hardware & Insulated Pipe Shoes
Fellow Subsidiaries: Sweco Fab: ASME Vessels, Pig Launchers, Duct Work, Strainers & Spectacle Blinds
 Pipe Shields: Pre-Insulated Pipe Supports, Slides, Guides & Anchors

Fronek Anchor/Darling
: Snubbers, Sway Struts & Sway Braces


Copyright © 2017  U.S. Bellows, Inc. All Rights Reserved. Privacy Policy