The document outlines guidelines and techniques for modeling expansion joints using CAESAR II software, focusing on detailed modeling inputs for bellows, hardware, and restraints. It also discusses quick modeling approaches, common errors, and addressing issues like rotation and rigidity errors in the modeling process. Furthermore, it provides information on calculating hinge friction and other critical variables relevant to expansion joint performance.

1. © Intergraph 2014
EXPANSION JOINTS WITH CAESAR II
Dan Edgar
Senior-Flexonics, Pathway Div

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CAU2014
PIPING ANALYSIS
&
EXPANSION JOINTS
Detail Modeling
Automated Modeling
Quick & Dirty Modeling
Common Errors

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DETAILED MODEL
DETAIL EXPANSION JOINT
MODELLING
° Bellows
° Hardware
° Restraints

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DETAILED MODEL
EXPANSION JOINT MODELLING
° Bellows
° Hardware
° Restraints

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DETAILED MODEL
TYPE OF BELLOWS INPUT
Long - Input length &
omit angular S/R.
Short - Leave length
blank and input all
values

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DETAILED MODEL
AXIAL INPUT

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DETAILED MODEL
LATERAL INPUT

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DETAILED MODEL
ANGULAR INPUT

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DETAILED MODEL
TORSIONAL INPUT

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DETAILED MODEL
Effective ID
Effective ID = (Af ∙ 4 / p )1/2
Af = Effective Area

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DETAILED MODEL
EXPANSION JOINT MODELLING
° Bellows
° Hardware
° Restraints

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DETAILED MODEL
HARDWARE - Input 1/4 of joint
weight for each end of the expansion
joint

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DETAILED MODEL
° Bellows
° Hardware
° Restraints

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DETAILED MODEL
RESTRANTS - Model rigid elements
and then connect with restraints
Restraint
Rigid Element

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DETAILED MODEL
TIED RESTRANTS - Tie Rods modeled as a
rigid & one end restrained by Cnodes

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DETAILED MODEL
HINGE RESTRANTS - Arms joined at
centerline and then restrained by Cnodes

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DETAILED MODEL
GIMBAL RESTRANTS - Arms joined at
centerline and then restrained by Cnodes

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DETAILED MODEL
Pressure Balanced Elbow / Tee

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DETAILED MODEL
Inline Pressure Balanced

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AUTOMATED MODEL
AUTOMATED EXPANSION JOINT
MODELING
(EXPANSION JOINT DATABASE)

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AUTOMATED MODEL

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AUTOMATED MODEL

23. © Intergraph 2014
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AUTOMATED MODEL

24. © Intergraph 2014
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AUTOMATED MODEL

25. © Intergraph 2014
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AUTOMATED MODEL

26. © Intergraph 2014
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AUTOMATED MODEL

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QUICK & DIRTY
QUICK & DIRTY EXPANSION JOINT
MODELING
(Tricking the computer)

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QUICK & DIRTY
Manipulating line input to
model an expansion joints
° Use zero length bellows
° Include weight & length in
adjacent rigid elements
° Use an infinitely large (10e6)
spring rate to model a restraint

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QUICK & DIRTY
TIED Expansion Joint:
Spring Rates:
Axial…………………. 10e6
Lateral ………………. Actual
Angular ……………… 10e6
Torsional ……………. Actual
Effective ID …………. 0
Inlet/Outlet - Ambient temperature
rigid elements with 1/2 the weight of
the unit

30. © Intergraph 2014
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QUICK & DIRTY
HINGED Expansion Joint:
Spring Rates:
Axial…………………. 10e6
Lateral ………………. 10e6
Angular ……………… Actual
Torsional ……………. 10e6
Effective ID …………. 0
° Inlet/Outlet - Ambient temperature
rigid elements with 1/2 the weight of
the unit.
° Restraint in axis perpendicular to
pins

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QUICK & DIRTY
GIMBAL Expansion Joint:
Spring Rates:
Axial…………………. 10e6
Lateral ………………. 10e6
Angular ……………… Actual
Torsional ……………. 10e6
Effective ID …………. 0
° Inlet/Outlet - Ambient temperature
rigid elements with 1/2 the weight of
the unit.

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ERRORS & OMISSIONS
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TYPICAL PROBLEMS
°Large Rotation Errors
°Relative Rigidity Errors
°Pressure Thrust Errors

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TYPICAL PROBLEMS
Large Rotation Errors

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TYPICAL PROBLEMS
Large Rotation Errors

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TYPICAL PROBLEMS
Large Rotation Errors

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TYPICAL PROBLEMS
Large Rotation Errors

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TYPICAL PROBLEMS
Large Rotation Errors

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TYPICAL PROBLEMS
Relative Rigidity Errors

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TYPICAL PROBLEMS
Pressure Thrust Errors

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TYPICAL PROBLEMS
Pressure Thrust Errors

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TYPICAL PROBLEMS
Pressure Thrust Errors

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Errors & Omissions
Hinge Friction

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Errors & Omissions
Hinge Friction
Mf = ½ • Ff • Dp = ½ • u • Pt • Dp
Or
F = Mf / ( ½ • L) = u • Pt • Dp / L
Where
Mf = Frictional moment in the plain of motion, in•lb
F = Frictional force at the bellows tangent, lbs
Ff = Frictional force at the pin surface, lbs = u • Pt
Db = Pin Diameter, in
Pt = Expansion joint pressure thrust, lbs
u = Coefficient of friction, either static or sliding. Sliding frictional values:
Steel on Steel 0.74
Case Hardened with dry lubricant 0.30
Lubricated steel 0.10

44. © Intergraph 2014
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Errors & Omissions
Hinge Friction

45. © Intergraph 2014
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Errors & Omissions
Hinge Friction