Turbine Crossover Bellows
Designed for Long Life and Special Application Problems
Traces of caustic carryover at a Southern California
Edison power generating station caused stress corrosion
of the turbine crossover bellows. Typically, these
expansion joints operate at 700 degrees F., 200 PSIG.
Caustic is an aggressive corrodent of nearly all commercially
available bellows materials when the operating
temperature is in excess of 500 degrees F.
Unalloyed nickel is the only expansion joint bellows
material generally considered to be resistant to caustic
stress corrosion at high temperature. The six expansion
joints furnished to Southern California Edison to solve
the problem were designed with a nickel inner ply to
resist caustic stress corrosion and an outer ply of Alloy
625 for strength. Because of the high design pressure,
the bellows were also reinforced with stainless steel root
rings.
Custom Expansion Joint Design and Manufacturing
A previous caustic induced failure at the same location
had caused an unplanned outage. To avoid any possibility
of an unplanned outage caused by leakage of the
crossover bellows in the future, the bellows were fitted
with the Senior Flexonics Pathway patented “red top”
leak detection system. This device senses any build up
of pressure between the bellows plies and warns the
operator if a leak has developed in the inner ply. With the
“red top” in place, any repairs or replacements due to
leakage of the inner ply could be safely planned for a
future scheduled outage.
For more information about Senior Flexonics Pathway
custom expansion joint designs for utility applications,
contact: Senior Flexonics Pathway.