Metallic Expansion Joints - Thorburn Flex Inc

THORBURN
FLEXIBLE PIPING SPECIALIST
ACCESSORIES
CONTROL RODS
Control rods are utilized to prevent excessive displacement of the bellows in a
universal expansion joint. These rods also control the relatively free centerspool
between the two bellows. These rods are not designed to restrain pressure
thrust forces.
TWO-PLY TESTABLE EXPANSION JOINT
The purpose of the 2-ply testable bellows is to provide a safety ply design. Each
bellows ply is designed to withstand the system design pressure independently,
so that in the event one ply fails for any reason, the remaining ply will enable the
expansion joint to continue to function in a normal condition. The space between
the bellows plies can be connected to a pressure gauge or a continuous
monitoring system. It would register any change in pressure and thus trigger
action to program replacement of the expansion joint on a routine basis.
TOROIDAL EXPANSION JOINT
Toroidal expansion joints are used in very high pressure systems. This type of
construction transmits most of the hoop loading from the convolutions to the
adjacent rings. This design allows relatively thin bellows to accept very high
pressures.
MULTI-PLY BELLOWS
Multi-ply bellows construction is used when increased fatigue life and lower forces
are required while still maintaining the same pressure capacity. The multiple plies
act in unison as far as hoop pressure loading is concerned, but act individually
when fatigue life and forces are calculated. Thorburn can also manufacture multiply
bellows with varying materials. This is especially useful when the media dictates
a material for corrosion protection, but one that is not strong enough to take the
pressure loading. This type of construction allows Thorburn to supply the most
economic bellows of optimum design for any individual application. Small holes
are drilled into the outer ply cuffs of a multi-ply bellows to provide for expansion of
entrapped air between the plies during high temperature operation.
HEAVY WALL BELLOWS
As a result of significantly improved fabrication capabilities, Thorburn now offers heavy wall single ply bellows to 3/16 of an inch (.187
inches, 4.76 mm) thickness and convolution heights ranging to 15 inches. These bellows possess reasonable spring forces as a result
of the high convolution configuration.
Bellows of this thickness quite often enable maintenance personnel to make temporary weld repairs, in many cases without system
shutdown. Such repairs might allow the system to continue to operate until a regularly scheduled shutdown occurs.
Heavy wall bellows are less susceptible to damage during installation and systems start-up. Multiple-ply bellows are available to a
thickness of 1/4 inch (.250 inches – 6.35 mm).
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