Metal Bellows Correctedn 7/11/00 2:41 PM Page 14
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ACCESSORIES
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STANDARD LINERS (PART NUMBER L)
Liners can be installed inside the expansion joint to protect the bellows
from damage. Liners should be specified by adding the letter L to the
part number when the following conditions exist:
• Smooth flow or low pressure drop is required.
• Velocities which may produce flow induced vibrations described below.
• For air, steam and other gases
a) Up to 6” Dia. flow greater than 4 ft/sec per inch of Dia. (Up to 150 mm Dia. flow greater than
0.05 M/sec per mm of Dia.)
b) Over 6” Dia. flow greater than 24 ft/sec (over 150-mm Dia. flow greater than 7.5 M/sec)
• For water and other liquids
a) Up to 6” Dia. flow greater than 1.67 ft/sec per inch of Dia. (up to 150 mm Dia. flow greater than
0.02 M/sec per mm of Dia.)
b) Over 6” Dia. flow greater than 10 ft/sec (over 150 mm Dia. flow greater than 3.0 M/sec)
HEAVY-DUTY LINERS (PART NUMBER HL)
Heavy-duty liners should be used in the following conditions:
• When high velocity, extremely turbulent or damaging two-phase flow exists upstream of the bellows.
• When extremely high temperatures are present, the liners can create an insulating barrier which would
permit the bellows to operate at lower temperatures ensuring longer life and resisting oxidation. Steam
purging and/or insulation can be added to enhance protection.
• When the media is erosive such as in catalyst carrying services.
• When an expansion joint is located within 10 pipe diameters downstream of an elbow, tee or valve.
When liners are specified, Senior Flexonics Pathway should be provided with the axial, lateral and angular
movement expected. This is required so that the diameter of the liner can be properly determined to avoid
interference with the downstream pipe or flange.
TIE RODS OR LIMIT RODS (PART NUMBER T)
This part number designation adds threaded rods that are designed to contain
pressure thrust. The rods will have nuts or stops on the ends of the assembly to limit
the overall length. When an expansion joint is designed for pure lateral offset the
rods are defined as Tie Rods. If the expansion joint is intended to absorb axial
motion as well as lateral offset, the rods will have outboard stops to limit the expansion joint to the installed
length plus any specified axial extension. This is defined as a Limit Rod. The designation “T” applies to
either purpose. The required movements determine if the rods are Tie Rods or Limit Rods. Limit rods are
generally used to limit expansion joint movement in the event of main anchor failure. During normal
operation Limit Rods do not contain pressure thrust.
COVERS (PART NUMBER C)
Covers should be specified when:
• Protection from falling objects or protection from traffic is needed.
• Protection of personnel is needed.
• Insulation will be applied over the expansion joint.
• When high flow velocities may exist around the outside of the
expansion joint, such as in the exhaust of a steam turbine.
Senior Flexonics Pathway always recommends a cover. The small cost for the cover is insurance against costly
downtime due to damage. The standard cover is a removable design.
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