The Ultimate Flue Gas Ducting Expansion Joint
Reliability AND cost savings
The most cost effective, longest-lasting flue gas metal rectangular expansion joint is a round corner, U-profile, integral flange design made with a heavy gauge of Corten or carbon steel material.
Features not to be compromised
The two features that will ensure long life on a metal rectangular expansion joint are a U-profile onvolution
and a round radius corner.
The U-profile is much more flexible than a V-profile and reduces stresses in the corner. The round radius corner further reduces those stresses. These two features eliminate the most common field failures of metal rectangular expansion joints. See past issue #17 – https://www.oakridgebellows.com/metal-expansion-joints/technical-articles/metal-rectangular-expansion-joints-that-last
along with the video – https://www.oakridgebellows.com/metal-expansion-joints/technical-videos/metal-rectangular-expansion-joints
Substitutions that cut big costs
Consider using a thick ply (1/8″) of carbon or Cor-ten
steel instead of expensive stainless steel. These carbon steels are common bellows material in boiler systems supplied by companies such as Combustion Engineering, Riley Stoker, and Babcock & Wilcox. And those parts often lasted 30+ years. An added bonus of the thicker material is the ease of field weld repairs.
Another major cost saver is eliminating the typical angle flanges and using the 1/8″ thick lip of the bellows. This lip can be seal welded to the adjacent ducting angle or channel in the field.
Many of the original angle flange connections end up
being seal welded anyway instead of the designed bolted connections. It’s rare for a bolted connection on a large duct to fit up; often in the field new holes need to be drilled, adding expense.
The Bottom Line
The ultimate flue duct metal rectangular expansion joint that is very reliable AND inexpensive has all of the above features – round corners, U-profile, integral flanges, made of thick carbon steel.