The document outlines the process and importance of pipe stress analysis for engineers, detailing the reasons for conducting such analyses, including maintaining stress within codes and optimizing piping design. It covers the scope of work for pipe stress engineers, applicable codes, methods of analysis, and specific calculations involved, emphasizing the significance of computer programs like CAESAR II. Furthermore, the document highlights designer responsibilities related to stress analysis and various considerations for supporting and routing piping systems effectively.

1. PIPE STRESS ANALYSIS WORK
Engineers 3D
Balu

2. AGENDA
1. Why Do We Perform Pipe Stress Analysis?.
2. Pipe Stress Engineer Scope of Work.
3. Theory of Pipe Stress Analysis.
4. Pipe Supports.
5. Applicable Codes.
6. Pipe Stress Analysis using Caesar II 5.20.
7. Code Compliances and Nozzle Evaluation.
8. Designer Responsibilities Related to Stress Engineering
Work.

3. 1. Why Do We Perform Pipe Stress Analysis?
• To keep stresses in the pipe and
fittings within code allowable.
• To keep nozzle loadings on
attached equipment within allowable
of manufacturers or recognized
standards (API 661, API 650 etc)
• To calculate design loads for sizing
supports and restraints.
• To determine piping displacements
for interference checks.
• To solve dynamic problems in
piping, i.e.: mechanical and acoustic
vibration, fluid hammer, pulsation,
transient flow and relief valve
discharge.
• To optimize piping design.
• To prevent flange leakage joint.

4. 2. Pipe Stress Engineer Scope of Work
-Depend on Client
Specification.
Review and
Comment on
Conceptual
Studies
Review 3D
Model and
Support Scheme
Review and
Approve the
Stress Isometric
Develop Critical
Lines List
Review Stress
Isometric
Revise the Piping
Layout & Isometric
Acceptable?
No
Yes
-Category 3 (Computer Analysis).
-Category 4 (Approximate Method).
-Category 5 (Visual Exam.).
-Modify pipe support
type and location.
-Add elbow to increase
piping flexibility.
-Stresses are within allowable.
-Nozzle loads are within allowable.
-Anchor and guide support location are
already fixed and already informed the
loading values to Civil Department.
-To prepare pipe support selection.
-To select pipe support based on
pipe support selection criteria.
-To check the 3D Model is comply
with the latest stress calculation or
not.

5. Pipe Stress Analysis Category
Method of Analysis:
1. Category 3
Using computer program
such as: Caesar II (Coade),
Autopipe (Bentley), PIPANL-
3 (SSD) etc.
2. Category 4
Using approximate methods
such as: the Kellogg,
Grinnell or Tube Turn
methods.
3. Category 5
Visual inspection with or
without the aid of guided
cantilever chart or similar
short cut methods.
Ref: KBR Design Manual
Subject No: 4100

6. 3. Theory of Pipe Stress Analysis
3. 1. Stress-Strain Curve
E
x
ε
σ 
Where:
σ = Stress (kg/cm2)
ε = Strain
E = Young’s Modulus (kg/cm2)
Allowable stress is the yield strength
divided by safety factor.
I.E : Carbon Steel Pipe below creep
range commonly has allowable stress
is 2/3* σy or ¼* σu. For detail see
Table A-1 in B31.3

7. 3. 2. Basic Stress Concepts
Stress due to axial force
σ = F / A
F = Axial force acting on cross section (kg)
A = Cross-sectional of pipe (mm2)
Stress due to bending and torsion
σb = Mb / Z
σt = Mt / 2Z
Mb = Bending moment (kg-mm)
Mt = Torsional moment (kg-mm)
Z = Section modulus of pipe (mm3)
Stress due to internal pressure
σH = PDi / 2t (Hoop)
σL = PDi / 4t (Longitudinal)
P = Design pressure (kg/mm2)
Di = Inner diameter (mm)
t = Thickness of pipe (mm)
Mt
Mb
F
F
σL
σH P

8. 3. 3. Thermal Effect
Thermal Expansion
δ = ΔT x α x L ; (mm)
Carbon Steel +/- 1 mm/m for 100oC
Stainless Steel +/- 1.35 mm/m for 100oC
Thermal Stress
σ = ε x Ε = δ/L x E
= ΔT x α x E
Reaction Force
F = σ x A
Example: 1meter length of 8” NPS CS Pipe STD at 100oC.
T ambient = 20oC
1. δ = (100-20)x12x10-6x1000 = 0.96 mm
2. σ = (100-20)x12x10-6x20000 = 19.2 kg/mm2
3. F = 19.2 x π x (2192-2032)/4 = 27.6 ton
δ (Pushed)
Force
Damage

9. 4. Pipe Support
4.1. Support Around Control Valve
Control Valve
Sliding Support
Tight Support Variable Spring Support Adjustable Guide
4.2. Spring and Adjustable Support

10. 4.3. Hold Down Guide
Sliding Plate
4.4. Anchor
Pad
Shoe
4.5. Spring Hanger Assembly
Eye Bolt
Spring Hanger
Turnbuckle
Pipe Clamp
Structure
4.6. Stopper

11. 5. Applicable Codes
• 5.1. Piping Design Code
 ASME B31.1 Power Piping
 ASME B31.3 Process Piping
 ASME B31.4 Pipeline (Hydrocarbon)
 ASME B31.8 Pipeline (Gas)
 ASME Section III Nuclear Component
Design
• 5.2. Related Code for Nozzle
Evaluation
 API Std 610 Centrifugal Pump
 API Std 611 Steam Turbines
 API Std 617 Centrifugal Compressor
 API Std 618 Reciprocating Compressor
 API Std 650 Welded Steel Tanks
 API Std 560 Fired Heaters (Furnace)
 API STD 661 Air-Cooled Heat Exchangers
(AFC)
 NEMA SM23 Steam Turbines
 ASME SEC VIII Pressure Vessel
 WRC 107, WRC 297 Local Stress on
Nozzles
ASME: The American Society of Mechanical Engineers
API: American Petroleum Institute
NEMA: National Electrical Manufacturers Association
WRC: Welding Research Council

12. 6. Pipe Stress Analysis using Caesar II 4.50
6.1. Required Data:
• Piping Configuration complete with
dimension.
• Material Spec. :Size, Thickness,
Material Properties, method of
bracing, etc.
• LDT (Line Designation Table):
Pressure, Temperature, Insulation
Thickness, Density etc.
• Equipment Drawing to determine
nozzle movement.
• Wind and earthquake loading.
• Standard valve and flange weight.
• Number of operating cycles if any.
• Misc. item drawing such as
silencer etc.
6.2. Item need to be concerned:
• Boundary Condition.
• Operating Case, i.e: pump, run or
stand-by.
• Friction.
K-3301A
K-3301B
K-3301C
V-1001
V-1002
Spring Hanger (Typ. 12ea)
Spring Support
Vertical Guide
Trunnion (Typ. 3ea)
Guide (Typ. 3ea)

13. 7. Code Compliances and Nozzle Evaluation
Primary Load Characteristics:
1. Primary loads are usually force
driven (gravity, pressure, spring
force, relief valve, fluid hammer etc).
2. Primary loads are not self-limiting.
3. Primary Loads are typically not
cyclic in nature.
4. Allowable limits for primary stress
are related to the material yield
stress, the ultimate strength or time-
dependent stress rupture due to
sustained load.
5. Excessive load causes plastic
deformation and rupture.
7.1 Primary vs. Secondary Loads
Secondary Load Characteristics:
1. Secondary loads are usually
displacement driven (thermal exp, anchor
movement, settlement, vibration etc).
2. Secondary loads are almost self-limiting.
3. Secondary Loads are typically cyclic in
nature except settlement.
4. Allowable limits for secondary stress are
based upon cyclic and fatigue failure
modes.
5. A single application of load never
produce failure.

14. 7.2. Code Stress Equations
• 7.2.1. B31.1 Power Piping 7.2.2. B31.3 Process Piping
H
o
A
sus S
t
Pd
Z
iM
.
S 


4
75
0
)
25
.
1
25
.
1
( SUS
H
C
A
C
EXP S
S
S
f
S
Z
iM
S 




H
o
B
A
OCC kS
t
Pd
Z
iM
Z
iM
S 



4
75
.
0
75
.
0
Where:
MA = Resultant moment due to sustained, kg-mm
SH = Allowable stress at operating temperature, kg/mm2
i = Intensification factor
Mc = Resultant moment due to expansion, kg-mm
SA = Allowable expansion stress, kg/mm2
MB = Resultant moment due to occasional, kg-mm
k = occasional factor
= 1.2 for loads occurring less than 1% of the time
= 1.15 for loads occurring less than 10% of the time
SC = Allowable stress at installation temperature, kg/mm2
H
o
o
o
i
i
m
ax
sus S
t
Pd
Z
M
i
M
i
A
F
S 




4
]
)
(
)
[( 2
/
1
2
2
)
25
.
1
25
.
1
(
]
4
)
(
)
[( 2
/
1
2
2
*
2
*
SUS
H
C
A
T
o
o
i
i
EXP S
S
S
f
S
Z
M
M
i
M
i
S 






H
l
SUS
OCC S
S
S
S 33
.
1



Where:
Fax= Axial force due to sustained, kg
Mi = In-plane bending moment due to sustained, kg-mm
Mo = Out-plane bending moment due to sustained, kg-mm
Mi* = Range of in-plane bending moment due to expansion, kg-mm
Mo* = Range of out-plane bending moment due to expansion, kg-mm
SH = Allowable stress at operating temperature, kg/mm2
ii ,io = In-plane, out-plane intensification factor
MT = Torsional moment due to expansion, kg-mm
SA = Allowable expansion stress, kg/mm2
SC = Allowable stress at installation temperature, kg/mm2
Sl = Bending stress due to occasional loads such as wind/earthquake
f = Stress range reduction factor

15. 7.2.3. B31.4 Liquid Transportation Piping
Yield
b
lp
sus x S
.
x
.
S
S
S 72
0
75
0



Yield
t
b
EXP S
S
S
S 72
.
0
)
4
( 2
/
1
2
2
* 


Yield
SUS
EXP
H
OPE S
F
S
S
S
v
T
Ea
F
S 9
.
0
)
1
( 






Yield
b
lp
OCC x k x S
.
x
.
S
S
S 72
0
75
0
*
* 


Where:
Slp = Longitudinal pressure stress, kg/mm2
Sb = Bending stress due to sustained, kg/mm2
Sb* = Range of bending stress due to expansion, kg/mm2
St = Range of torsional stress due to expansion, kg/mm2
Sb** = Bending stress due occasional, kg/mm2
Syield = Specified minimum yield stress material, kg/mm2
F = 1 (under ground pipeline); 0 (above ground pipeline)
E = Modulus of Elasticity
a = Thermal expansion coefficient
ΔT = Temperature change of pipe from ambient
v = Poisson’s ratio
SH = Hoop stress kg/mm2
k = Occasional load factor
7.2.4. B31.8 Gas Transportation Piping
T
S x F x
.
S
S
S b
lp
sus 75
0



S
S
S
S t
b
EXP 72
.
0
)
4
( 2
/
1
2
2
* 


S
S
S
S SUS
EXP
OPE 


x T x k
x S x F
.
S
S
S b**
lp
OCC 75
0



Where:
Slp = Longitudinal pressure stress, kg/mm2
Sb = Bending stress due to sustained, kg/mm2
Sb* = Range of bending stress due to expansion, kg/mm2
St = Range of torsional stress due to expansion, kg/mm2
Sb** = Bending stress due occasional, kg/mm2
S = Specified minimum yield stress material, kg/mm2
F = Construction type
T = Temperature derating factor
k = Occasional load factor

16. 7.3. Nozzle Evaluation
7.3.1. Pump (API Std 610)

17. 7.3.2. AFC (API Std 661)

18. 7.3.3. Pressure Vessel/Heat Exchanger (KBR Specification)
Note: For detail see Halliburton KBR Specification
Doc. No: 308-7080-ST-54-101

19. 7.3.4. Furnace (API Std 560)

20. 7.3.5. Compressor and Turbines (NEMA SM23)
e
R
R D
M
F 500
3 

e
R
R D
M
F 500
3 

Fx = 50 Dc
Fy = 125 Dc
Fz = 100 Dc
Mx = 250 Dc
My = 125 Dc
Mz = 125 Dc
Individual Forces and Moments
Total Resultant Forces and Moments
Combine Loads for Inlet and Outlet
e
R
R D
M
F 500
3 

C
C
C D
M
F 250
2 


21. 7.3.6. Tanks (API Std 650)
Note:
Appendix P on API Std 650 shown that the nomogram is
only applicable for tanks larger than 36 m in diameter.
If not we will use WRC297 to verify our piping loads are
within allowable or not , but it will be better to ask Tank
Department to verify our piping loads.
API Std 650 is not mention how to verify the nozzle loads at
roof of tank.

22. 8. Designer Responsibilities Related to Stress Analysis Work
• To prepare stress sketch/isometric drawing based on critical line
list from stress engineer.
• To prepare piping loading information for Civil and Equipment
Department and Stress Engineer shall indicate the loads.
• To utilize the span table for horizontal support (guide) and
vertical support (resting).
• To select a proper pipe support based on pipe support selection
criteria and stress sketch from stress engineer.
• To inform the clearance for spring support installation.
• To prepare misc. support drawing as needed and then shall be
verified by Stress Engineer.
• Etc.
•

23. 8.1. Piping Loading Information to Equipment
Plan View

24. 8.2. Around Pump
Adjustable Support
Items to be concerned:
1. Shortest suction line shall be planned to
minimize pressure loss.
2. Adjustable supports shall be installed for
suction and discharge line for pump
maintenance and alignment and the
location as close as possible to the
nozzle.
3. Care shall be taken in thermal stress
calculations because the entire piping
does not always have the same
temperature, depend on operation plan.
4. To relieve reaction force and moment
due to thermal stress on the piping,
expansion loops and restraint supports
such as anchor, stopper, guide, resting
and spring support shall be used.

25. Sway Brace
Reactor
Fired Heater
Sway Brace
Adjustable Guide
Constant Hanger
Lift Off
Constant Hanger
Items to be concerned:
1. Piping shall be designed to have
sufficient flexibility but it shall be arranged
as short as possible.
2. Piping support around reactor shall be
selected to eliminate the vibration and
excessive forces and moments to the
reactor nozzle due to thermal stress.
Fixed type support shall be installed as
close as possible from the nozzle.
3. Sway brace is vibration eliminator and
identical to variable hanger in their
resistance against thermal expansion, so
should be installed at location where the
thermal displacement is as smaller as
possible.
8.3. Around Reactor and Fired Heater

26. Re-strut
Adjustable Guide
Vessel
Compressor
Re-strut
Items to be concerned:
1. Piping route shall be flexible to prevent
excessive forces and moments on the
compressor nozzle.
2. Piping support shall be installed well
balanced so no excessive forces and
moments on the compressor nozzle.
3. Piping connected to and from suction
and discharge of compressor shall be
equipped with vibration proof as
required.
4. Vibration proof piping support shall
allows piping movement caused by
thermal expansion and prevent piping
vibration caused by compressor.
5. Sleeper support shall be adopted to
abate the vibration of piping and shall
be not connected or closed to
compressor shelter to prevent sleeper
piping vibration is transmitted to shelter.
6. To check the natural frequency of
piping system against compressor.
7. Expansion joint shall not be used for
vibrating line which may cause
damage.
8.4. Around Compressor
Compressor
Adjustable Guide
Re-strut

27. Items to be concerned:
1. Support arrangement of piping manifold
shall be prepared to make it simple and
economic.
2. Piping route shall be flexible to prevent
excessive forces and moments on the
AFC nozzle.
3. Piping support around AFC shall be
selected to eliminate the vibration and
excessive forces and moments to the
AFC nozzle due to thermal stress.
Stopper type support shall be installed
as close as possible from the center of
piping manifold.
4. Vibration due to slug force can be
eliminated by install properly stopper
and guide support.
Vessel
AFC
Stopper
8.5. Around AFC

28. THE END