Applies To
Product(s):	AutoPIPE
Version(s):	ALL;
Area:	Results
Date Logged & Current Version	Oct. 2017 11.01.00.23

Model Definition

AutoPIPE:

The model taken is a pump system where Pump A(Point 1) or Pump B(Point 90) or both Pump A and B are in operation. The point 170 is connected to a vessel oriented in Z axis and at this point we enter a flexible anchors(by CAESAR under the WRC297 and by AUTOPIPE under user flexibility)

Pipe OD at Pump A or B	168.3 mm
Wall Thickness at Pump A or B	7.1 mm
Pipe OD after the reducer	219.1 mm
Wall Thickness after the reducer	8.2 mm
Temperature for the pump in Operation	450 degC
Temperature for spare Pump	80 degC
Material	A106B
Piping Code	B31.3:2006
Allowable Stress at 80 degC	137.89 N/mm2
Allowable Stress at 405 degC	86.29 N/mm2
Pressure	10 bar
Earthquake Loading	AutoPIPE Number of load cases : 4 Load case 1 - E1 X-Multiplier= 0.100 Y-Multiplier= -0.050 Z-Multiplier= 0.000 Load case 2 - E2 X-Multiplier= 0.000 Y-Multiplier= -0.050 Z-Multiplier= 0.100 Load case 3 - E3 X-Multiplier= -0.100 Y-Multiplier= -0.050 Z-Multiplier= 0.000 Load case 4 - E4 X-Multiplier= 0.000 Y-Multiplier= -0.050 Z-Multiplier= -0.100	caesar UNIFORM LOAD Changes U1 X1 Dir = .10 g`s Y1 Dir = .00 g`s Z1 Dir = .00 g`s U2 X2 Dir = .00 g`s Y2 Dir = -.05 g`s Z2 Dir = .00 g`s U3 X3 Dir = .00 g`s Y3 Dir = .00 g`s Z3 Dir = .10 g`s E1= U1+U2 (CAESAR) E2=U2+U3(CAESAR) E3=-U1+U2(CAESAR) E4=U2-U3(CAESAR)
Wind Loading	Number of load cases : 4 Ground elevation for wind : 0.00 mm Wind shape factor multiplier : 0.700 Exposed Segments - A B Wind application method : Normal Load case 1 - W1 X= 1.000 Y= 0.000 Z= 0.000 Load case 2 - W2 X= -1.000 Y= 0.000 Z= 0.000 Load case 3 - W3 X= 0.000 Y= 0.000 Z= 1.000 Load case 4 - W4 X= 0.000 Y= 0.000 Z= -1.000 User defined wind profile Height (mm) Press (N/m2 ) ----------- -------------- From : Ground to : 7000.00 480.00 to : 10000.00 540.00 to : 15000.00 630.00 to : 20000.00 700.00 to : 25000.00 760.00 to : 50000.00 990.00
Valves between 10-15,15-20,70-75,75-80 Nodes Weight	5000 N each
Reducer between 1-5,85-90 Nodes OD1/WT1 OD2/WT2	. 168.3 mm/7.1mm 219.1 mm/8.2mm
Welding Tee	Node point: 45
Elbow Radius 1.5 OD=304.8 mm	Node points: 25,40,50,60,65,105,115,120,130,140,150,155
Spring Hanger	Node Point 20: Stiffness Rate:133N/mm ,Cold load:14083 N Node Point 35: Stiffness Rate: 67N/mm ,Cold load:5928 N Node Point 55: Stiffness Rate: 67N/mm ,Cold load:4943 N Node Point 70: Stiffness Rate:133N/mm ,Cold load:14547 N
V-Stop(+Y support)	Node points: 110,125,135,145 Support Friction=0.3
Line Stop (Stop in X direction) simulated by an incline support	Node point: 110 Support Friction=0.3
Flexible Nozzle AutoPIPE used User Flexibilities CAESAR II used WRC297	Node point: 170 Vessel Axis = Global Z Axial Translation Stiffness=32422 N/mm Longitudinal Bending Stiffness=39422 Nm/deg. Circumferential Bending Stiffness=8916Nm/deg.
Thermal Anchor Movements:	Node point: 1, 90 Case T1: DY = 2.35mm, Case T3: DY = 2.35mm Case T2: DY = 2.35mm, Case T3: DY = 2.35mm

RIGID Support and Anchor Stiffness

AutoPIPE

caesar

Support Rigid Stiffness
Translation: 1.7512 E+9 N/mm
Rotation: 1.3558E+12 Nm/degree

Anchors Rigid Stiffness
Translation: 1.7512 E+9 N/mm
Rotation: 1.3558E+12 Nm/degree

Default Friction Stiffness: 1.7512e+10 N/mm

AUTOPIPE does not allow you to change the friction stiffness but the friction tolerance is used to check analysis convergence.

Support or Anchors Stiffness
Translation: 1.75E+11 N/mm
Rotation: 1.1298E+11 Nm/degree

Friction Stiffness: 4.38e+006 N/mm

The friction stiffness, the friction angle variation, the friction slide multiplier and the coefficient of friction are able to be set in the configuration file.

Simulated Valves

AutoPIPE

caesar

AutoPIPE assumes that a valve is 100 times stiffer than the connecting pipe material at the start of the valve.

The Surface Area Factor is the factor used to multiply the insulation weight of the pipe per units length to get the insulation weight of the valve per units length.

To simulate the rigid element like CAESAR II , the valves are going to be modeled like an element with 10 times the wall thickness of the pipe and we will have to correct the weight entered(5000 N) because in this case the weight per meter is much bigger.

PIPE3 is the pipe with 82 mm wall thickness.

The weight of the pipe total =3170 N/m
The element 533 mm= 1689.6 N
The element 419 mm=1328.2 N

The weight of the check valve(533 mm) to be entered should be :
5368.9-1689.6= 3679.3 N

The weight of the check valve(419 mm) to be entered should be :
5289.8 N-1328.2 N=3961.6 N

The insulation density has been changed from .2 Kg/dm3 auf 1.75 x .2=.35 Kg/dm3

CAESAR II forms rigid elements by multiplying the wall thickness of the element by 10. The inside diameter, and the weight of the element, remain unchanged.

The weight of insulation added is equal to the same weight that would be computed for an equivalent straight pipe times 1.75 and cannot be changed.

According to CAESAR II Miscellaneous Data

The element 533 has a total weight of
9381+439+253=10073 N/m

That means a weight of 5368.9 N

The element 419 has a total weight of
11933+439+253= 12625 N/m

That means a weight of 5289.8 N

Post Processing Load Case (Non-linear)

Sustain Stress

AutoPIPE

caesar

GR(1)=GR+MaxP(1)

GR=Weight
MaxP(1)=The max pressure into the system (Between P1,P2,P3)
(1)=Analysis Set 1

L13=W+P1+H
L14=W+P2+H
L15=W+P3+H

-W=Weight
-P1=Presure 1
-P2=Pressure 2
-P3=Pressure 3
-H=Hanger

No stress

Operating loading cases are only to check the displacements & forces and moments

AutoPIPE

caesar

GT1(1)=GR(1)+T1(1)
GT2(1)=GR(1)+T2(1)
GT3(1)=GR(1)+T3(1)

T1(1)=Temperature 1 for analysis set 1
T2(1)=Temperature 1 for analysis set 1
T3(1)=Temperature 1 for analysis set 1

L2=W+D1+T1+P1+H
L3=W+D2+T2+P2+H
L4=W+D3+T3+P3+H

T1=Temperature 1
T2=Temperature 2
T3=Temperature 3
D1 =Displacement by T1
D2=Displacement by T2
D3=Displacement by T3

Expansion Stress

Operating loading cases are only to check the displacements & forces and moments

AutoPIPE

caesar

Amb to T1(1)
Amb to T2(1)
Amb to T3(1)
Max Range
GR(1)--> P1(1) P1(1)>T1(1)

Thermal expansion from Ambient temperature to T1(1),T2(1),T3(1)
Through the load sequencing, we start to apply 1st the weight(GR) ,2nd the max Pressure ,3rd the temperature.
Max Range=the maximum difference between the temperatures(T1,T2,T3)

Exp1=L2-L13
Exp2=L3-L14
Exp3=L4-L15

Occasional Case - Static Earthquake

The combination is done by summation of the absolute value of each term at the stress level

AutoPIPE

caesar

E1 = in x and -1/2 x in y dir
E2 = in -x and -1/2 x in y dir
E3 = in z and -1/2 z in y dir
E4 = in -z and -1/2 z in y dir

Dir = direction

To be checked:

SUS+E1
SUS+E2
SUS+E3
SUS+E4

SUS = GR(1) +MaxP

U1=in x dir
U2=-1/2 x in y dir
U3=in z dir
To be build:
L5=OP1+U1+U2
L6=OP1-U1+U2
L7=OP1+U2-U3
L8=OP1+U2-U3
L19=L5-L2=U1+U2
L20=L6-L2=-U1+U2
L21=L7-L2=U2+U3
L22=L8-L2=U2-U3
To be Checked:
L13+L19
L13+L20
L13+L21
L13+L22

U is for uniform load in g
U1+U2=E1
-U1+U2=E2
U2+U3=E3
U2-U3=E4
OP1=Operating 1
The check has been done only for OP1.It should be repeated for OP2 and OP3
To be able to check the non linear effect of static earthquake ,a loading case OP1+static Earthquake has to be build and after this loading case minus the OP1, give us the non linear effect of the static earthquake which has to be added to the sustain in Absolute value.

Occasional Case - Wind

The combination is done by summation of the absolute value of each term at the stress level

AutoPIPE

caesar

W1 = Wind in X dir
W2 = Wind in -X dir
W3 = Wind in Z dir
W4 = Wind in -Z dir

To be checked:

SUS+W1
SUS+W2
SUS+W3
SUS+W4

A User Profile is going to be given (a Pressure per elevation)

WIN1=Wind in X dir
WIN2=Wind in -X dir
WIN3=Wind in Z dir
WIN4=Wind in -Z dir

A User Profile is going to be given (a Pressure per elevation)
The same system has to be used as the static earthquake.

The Units File

AutoPIPE

caesar

By Autopipe you can create your own units file but you have to define your own conversion coefficients. The basic is the English units(English.unt)

and we have created a metric units file called CAESAR.unt)

The Units file to be used is set under:

General Model Options dialog

A different units file for the input and output can be set. If you need to change the units, you can always go back to General Model Options dialog and change it.

AUTOPIPE.unt are set per default in English units. If you change the name for instance SI.unt into AUTOPIPE.unt. The default unit is going to be SI.

By CAESAR II you can as well create your own units but the conversion factors are already calculated for you and you only need to choose the units you want. The basic calculation is as well done in English units. The units file is called for instance FUCHS.fil and have to be stored into the system directory from CAESAR II to be able to be used on all calculations.

Once you set by the CAESAR.CFG the default units file, the input you create is set to these units.

To get other units by the output, you only need to change the units in the configuration file after that. It is always possible to change the input units

By using CAESAR Tools/convert Input to new units

The Configuration File

AutoPIPE

caesar

Edit Model options Dialog.

The configuration file from CAESAR II is located in the working directory and not attached to the input file. That means that it is a common file from a certain directory. The main disadvantage is that if you change anything in this config because of a certain input and you rerun another input under this directory, the results are going to be changed..

Analysis Loading Definition

AutoPIPE

caesar

AUTOPIPE static analyses by load increments.

It is important to note that in an AUTOPIPE analysis, each load case is an increment of load, not a total load as in Caesar.

For a linear analysis, the results for each load case are obtained all at once and the “Gaps/Friction/Soil" option has to be disabled.

For a nonlinear analysis the results are obtained sequentially.

Non-Linear load increments, the steps are:

1-Analyze for Gravity; then
2-Analyze for thermal, specifying gravity as the initial state i.e. GR->P1->T1

The “Static analysis set” is set under Loads/Static Analysis Set

Note: Ignore Friction E and Ignore Friction GR options have to be unchecked since CAESAR II the friction is always acting

The code and non-code combinations are created automatically and we can define as many analysis sets up to 999 and combine the results as we want.

User non-code combinations can be created and typically used to create operating cases to examine maximum forces and moments on equipment nozzles and supports or anchors.

Note: The hydrotest is a linear analysis and typically defined in a 2nd analysis set to define this case.

GT1=GR+T1 -> Operating 1 by CII
GE1=GR+E1 -> SUS+U1+U2 by CII
GW1=GR+W1 -> SUS+WIND1 by CII

We have as well to define operating 1 + Wind1 by the non-code combination to define the maximum forces and moments on supports.

Load Combinations can be selected for printing

CAESAR II is performing analyses for total loads.

That means that CAESAR II is throwing every item (Weight, displacements, Temperature and so on) in a basket and adds everything together regardless when it happens.

If analyses are performed for total loads, the steps are:

1-Analyze for gravity(Weight)
2-Analyze for gravity(Weight) +Thermal(T1) =OP1 (Operating case) ,then
3-subtract step 2 from step 1 to obtain thermal

The loading cases will look like:

L1=W+P1(SUS)
L2=W+P1+T1+D1(OPE)
L3=L2-L1(EXP)

SUS= sustained
OPE=Operating case
EXP= Expansion case=Stress range

To sum up ,you can find following annotations

AutoPIPE	caesar
Gr T1 GT1 W1 (Wind) E1	W+P1 T1+D1 W+D+T1+P1 Win1 (wind) U1 (earthquake)

To obtain non linear analysis in Caesar II, create a loading case operating, then operating + wind or +earthquake, then subtract the operating + wind or + earthquake from operating alone. Then this occasional load will be added to the sustained stresses and compare to 1.33 Sh for instance by ASME B31.3

By the load case editor, you can define the type of loading. To notice that the basic allowable stresses taken are set by the stress type:

SUS -> sustained stress against Sh
EXP -> Expansion stress against SA=f (1.25 Sc+0.25 Sh) when the liberal stress is not activated Otherwise SA=f (1.25Sc+0.25Sh) + (Sh-SL) when the liberal stress is activated.

This is activated by the CAESAR II Config. OPE -> there is no stresses check, it is only valid to check the forces and moments. It is important to notice that first the basic loading cases are defined, then their combinations

It is always possible to save the loading cases to be able to reuse it on other input.

In the load case options , you can define the output statut: which allows you to specify whether or not you will be able to check the loading case.

Output type:

To define on which level your combination is going to be (at diplacement/force/stress or at Dipl/force or Disp/stress or force/stress or disp or force or stress).

Combination method: Algebraic ,Scalar ,SRSS ,Abs ,Max ,Min ,SignMax ,SingMin

Snubbers: active or not active

Hanger stiffness: Rigid, Ignor ,as design

Elastic Modulus: Ec or Eh

Friction multiplier: to turn on(1) or off (0)the friction

With our example having 4 loading cases in Static earthquake and 4 wind directions,we end up having already 36 loading cases defined with the friction on.As the friction is not always acting,we should do the same loading cases without friction.

CAESAR II loading became quite complicated

For the wind load, we define the wind pressure per elevation or use other codes.

Input Check

AutoPIPE

caesar

Big advantage using AutoPIPE, check the input using 1 of 2 methods :

1. Input grid
2. Model input listing

Setup File Parameters

Pipe Properties

Note: This is the simulation of the rigid element with 10 times the wall thickness but the weight is kept the same and the insulation are multiplied by 1.75

Pipe Properties

Reducers

Elbows

There are very small differences between SIFI ,SIFO .Autopipe has only one flexibility factor, CAESAR II has 2(inplane / outplane) but same value

Elbows

Tees

Material Data

Material Data.

Temperature and Pressure

Anchor Movements

Restraint System

Spring Hangers

Flexible Nozzle at 170

Earthquake Load-cases

E1= U1+U2
E2=U2+U3
E3=-U1+U2
E4=U2-U3

Wind Load-cases

Results Comparison

AutoPIPE

caesar

Max GR(1) Stress

The difference(37.52-36.91) is 1.6%

Max Displacement DY

The difference(9.36-9.35) is 0%

Max Displacement DX

the difference(2.8-2.79) is 0%

Max Displacement DZ

The difference(5.7-5.67) is 0%

Stress comparison in Temperature T1,T2,T3

T1(1)Max Stress =67.89 N/mm2 :difference = 5.1%

T2(1)Max Stress =67.13 N/mm2 :difference = 0.4%

T3(1)Max Stress =68.07 N/mm2 :difference = 3.7%

Stress comparison in Temperature T1,T2,T3

EXP(T1) Max Stress = 64.4 N/mm2

Highest Stresses: (N./sq.mm. )
LOADCASE 16 EXPANSION CASE CONDITION 1
CodeStress Ratio (%): 33.2 @Node 130
Code Stress: 64.4 Allowable: 193.9

EXP(T2) Max Stress non linear= 67.4 N/mm2

Highest Stresses: (N./sq.mm. ) LOADCASE 17 EXPANSION CASE CONDITION 2
CodeStress Ratio (%): 34.7 @Node 98
Code Stress: 67.4 Allowable: 193.9

EXP(T3) Max Stress non linear= 65.5 N/mm2

Highest Stresses: (N./sq.mm. ) LOADCASE 18 EXPANSION CASE CONDITION 3
CodeStress Ratio (%): 33.8 @Node 130
Code Stress: 65.5 Allowable: 193.9

Comparison of Sustained and Thermal Forces and Moments

Non-Linear Analysis

Notes:

1. With +ve % difference results are CAESAR II bigger than AUTOPIPE. On 28 results, 23 cases CAESAR II gives higher Forces and Moments.

When the difference is above 6.6 % ,it is always the case that CAESAR II is calculating higher forces and moments. The maximum difference is 24.2%.

2. AutoPIPE has a more advanced non-linear analysis engine with load sequencing and we can expect a more accurate non-linear results than CAESAR

Node Point 1

Node Point 90

Linear Analysis

Notes:

To get CAESAR II to make analysis linear, set the restraints as Y instead of +Y supports at node points: 110 ,125,135, and 140. If enter as +Y, the supports are non linear. The friction by the loading cases are set to zero.

That means that you cannot do a linear analysis on the same input. We have to create a separate input to set up the conditions for non-linear analysis.
AUTOPIPE is able on the same input to have non-linear and linear analysis because it can create a new analysis set with the linear conditions.

Node Point 1

Node Point 90

Comparison of Occasional Loads in T1 temperature case

Non-Linear Analysis

Notes:

1. With +ve % difference results are CAESAR II bigger than AUTOPIPE. On 32 results, 23 cases CAESAR II gives higher Forces and Moments.

One result, AUTOPIPE is bigger than CAESAR II ,we have a difference of 17%. Otherwise in most cases CAESAR II is calculating higher forces and moments with a maximum of 19.3%

2. AutoPIPE has a more advanced non-linear analysis engine with load sequencing and we can expect a more accurate non-linear results than CAESAR

Node Point 1

Node Point 90

Linear Analysis

Notes:

1. The Linear Results are consistently under 5% difference, with only one result at 6.1 %

Node Point 1

Node Point 90

CONCLUSION

To provide specific answer to even a slightly complex system differences like the system at hand would require all the assumptions and methods adopted in both the applications completely, which is not practical.

Comparing results between two applications is always tricky and are bound to be different apart from very simple cases. Although the basic theory and assumptions behind the two applications may be the same, but as the products evolve the different components may start to diverge slightly based on selected options. These divergences may compound when the models depart from being very simplistic models.

For example, if you run very simple cantilever models in both the applications with a tip force applied, you will get exactly the same results:

Length of pipe (ft)	Free end force (lbf)	AP Displacement (in)	CII displacements (in)
0.5	10,000	0.0008	0.0008
1.0	10,000	0.0021	0.0021
2.0	10,000	0.0085	0.0085
5.0	10,000	0.0946	0.0946
10.0	10,000	0.7135	0.7135

This could tell us that both the applications are using the same beam theory with shear deformation included. When we depart from simplistic models then some assumptions / implementations like below may come in to play:

Rigid support stiffness values
Rigid elements stiffness values defined for the two applications
Bend elements formulation
Flexible joints formulation
Pressure thrust load vector formulation
Post processing assumptions and options
Many other

On individual level, there may be slight differences in these formulations. However, when the whole system is analyzed, the differences may get compounded due to interaction of these individual differences. One can trust any application if one understands the assumptions involved in the solution and understands that the results are a fair approximation of the actual system. Some applications may have a better representation of a particular component / analysis, while the other may be good in another area.

A good way to gain more confidence in to any application results is to start with simple models, perform a few tests on the component / analysis, and confirm that the results simulate the actual system reasonably well. AutoPIPE QA program backs up the results generated by the program with a rigorous set of hand calculations and published results.

To sum it up, AUTOPIPE has a more advanced non-linear analysis engine with load sequencing and we can expect a more accurate non-linear results than CAESAR II. Caesar non-linear results are consistently higher than AutoPIPE. By the comparison, the maximum differences for Stresses and Displacements was 5.1 %.

See WIKI here for typical reasons why results may be different.

08. AutoPIPE vs Caesar Benchmark

AutoPIPE:

RIGID Support and Anchor Stiffness

Simulated Valves

Sustain Stress

No stress

Expansion Stress

Occasional Case - Static Earthquake