systems containing bellows and external main anchors (compression
system) must be guided by full lateral restraint type guides.
No more than one bellows should be used between any two
anchors. Hence if more than one bellows is required, the
piping system should be divided up into sections, containing
one bellows each, by intermediate anchors. Intermediate
anchors do not carry pressure thrust load, but must be designed
for bellows deflection forces and frictional forces from
supports and guides. See reference1 for more
information on this subject.
are several important reasons for the requirement for guides:
motion into the bellows
the ends of the bellows against "squirm"
buckling of the pipe due to pressurized fluid column effect
for guiding of pipe containing bellows are given in Reference1
of pipe due to the compression effects of a pressurized
fluid column is not a widely understood phenomenon. In a
"tension system", where normal longitudinal tensile
load is maintained, this cannot happen, no matter how long
the un-supported (or guided) length of pipe. However, in
a "compression system" a column buckling effect
can occur, even when there is no externally generated longitudinal
compression load on the pipe. Normally, with a bellows there
is a longitudinal compression in the pressurized pipe due
to bellows sidewall load. However it is the full bellows
thrust area which determines the buckling pressure.
the following arrangement: