Caesar Tutorial

8/10/2019 Caesar Tutorial

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System Overview

This tutorial presents the flexibility and stress analysis of a piping system using CAESAR II. This process includesthe creation and entry of the pipe stress model, the analysis and evaluation of the results, and a re-design of thesystem. The system chosen for this purpose, though small, exercises common modeling situations, as illustrated

in the figure below. As noted on the drawing, this system moves crude tower bottoms from the bottoms pump toa steam stripper unit, which is utilized in a refining process. The end suction, top discharge pump has a 10-in.suction nozzle and an 8-in. discharge nozzle. The 8-in. line runs through a check valve with a 6-in. bypass, to aspring hanger support. Then it runs over a hard support before entering the vertical vessel.

The Tutor Piping System Layout



Chapter 7 Tutorial A 7-3

The boundaries of this system are the pump discharge nozzle and the vessel nozzle. Other acceptable choicescould have been the pump support (or base) point and the vessel foundation. The pump nozzle is a satisfactory

boundary because the movement of that point (as the pump heats up in operation) is rather certain and easilycalculated from the thermal strain between the pump nozzle and the base point. The vessel nozzle is an adequate

boundary because of the known thermal growth of the vessel and the greater stiffness of the vessel, with respect

to the 8-in. pipe. An opposite approach may be taken by running the model all the way to an immovable point,which is the vessel foundation.

The check valve sits on top of the welding tee for the 6-in. bypass piping. The 6-in. line runs through a gatevalve before re-entering the 8-in. line through a second welding tee above the check valve. The total weight andlength of this valving is unknown at this time. Therefore, the valve lengths and weights were pulled in from the

CAESAR II

The hanger is included at the top of the vertical run to carry the deadweight and absorb its thermal growth. Thehanger is attached to the elbow and in line with the vertical pipe at the “near” end of the elbow. (Near is a termassociated with the path used to define the elbow. By coding up the vertical leg and then the horizontal leg, theweld point on the vertical run of the elbow is the near end and the horizontal run weld point is the far end.) The

other end of the hanger is attached to some available structure above this point. Because of the vertical thermalgrowth of the hanger attachment point, a simple rod hanger is not acceptable here. The analysis will be set to

force

generic database. Note that the spring hanger above this valving will be quite sensitive to theweights used here. The difference between the actual installed valve weights and modeled weights should be

used to adjust the spring pre-load. Verify that the hot load on the spring is toward the center of themanufacturers-recommended spring working range to allow errors in load estimation. If there is any appreciable

change in these weights, the system should be re-analyzed.

CAESAR II

The horizontal piping rests on an unspecified support at the far end of the next elbow. This support, modeled as arigid, nonlinear restraint acting on the pipe centerline, allows the piping to grow upward, but prevents downward

motion. In cases where a more accurate model for supporting structures is required, include structural steel in the

model and analysis.

to select a variable or constant support hanger at this point. The program will probably select avariable spring support. For that reason, the Anvil table is specified for its selection.



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Preparing the Drawing

The following figure shows the drawing used to construct the model. Immediately apparent are the nodenumbers. These labels are assigned where there is a change in geometry (a pipe diameter, wall thickness, orchange in direction), a change in materials, operating conditions (temperature or pressure), or the application of

boundary conditions (restraints, point loads, displacements, and so on). Additional node numbers should be

assigned at any other location for which output is desired. For this tutorial the progression is incremented by 5’sstarting with node 5 at the pump nozzle. These nodes are the basis through which the piping stress isometric istabulated for the analysis. The bypass piping also has the 5’s progression but they are incremented by 600. In

reviewing the results the 600 series will indicate 6-in. pipe.

Tutor Example with Node Numbers and Other Technical Information




Note how the elbows are shown squared with the node assigned to the intersection. The elbows will be definedso that output is available for the near, mid, and far points of the bend (at 0, 45, and 90 degrees). The hanger will

be sized at the first elbow’s near point (node 28).

Other information required for the model is collected on this drawing before the program is started. Most of the

data should be readily available but some research may be required. Items such as pump nozzle deflections andvalve data details can slow down the input session if not noted on the drawing. The next figure shows thedimensions for this system.

Tutor Example with Dimensions



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Generating CAESAR II Input

Before beginning the input session, it will be useful for this tutorial to set the numeric increment between nodes.In the previous discussion, it was stated that node numbers would use an increment of 5 for this model. Thedefault nodal increment is 10, so this must be changed. From the Main Menu, select TOOLS-CONFIGURESETUP andthe window shown below displays. Next, choose the Geometry Directives tab. Select the number 5 from the

drop list in the Auto Node Number Increment item as shown in the following figure. Click Exit w/ Save tosave this change and return to the Main Menu.

Changing the Auto Node Number Increment in Configuration Setup

Click the CAESAR II icon to start the program. CAESAR II will confirm the External Software Lock (ESL)

connection. Next, click FILE-NEW and enter a new filename of Tutor in the resulting dialog. Be sure to note the

data directory path that you will create and store the file in. You may want to use the Browse button to chooseanother directory for storage of your CAESAR II data files.

New Job Name Specification Dialog Box




Start the input session by selecting INPUT-PIPING from the Main Menu. If the job is new, CAESAR II will presentthe list of input units that will be used. Otherwise, if a job by the name Tutor already exists on the machine, the

first piping element spreadsheet will appear. If this is the case, exit out of this input by clicking the X in the top-right of the window or by selecting FILE-EXIT from the menu. Return to the Main Menu to pick an unused

jobname. The following window will be displayed if the file is new.

Tip: The Review Current Units

If the

window displays only if the file is new and did not previously exist in the data directory.

Units File Label field (bottom left of the Review Current Units dialog box) does not show English Unitsthen click Cancel. Select TOOLS-CONFIGURESETUP, click the Database Directives tab and select English in theunits drop list there. If the English units are shown, click OK to continue with the input. An empty pipingelement input spreadsheet will appear as shown in the following figure.



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Blank Input Spreadsheet

All the input spreadsheets for this tutorial are provided on the following pages. Individual spreadsheets may berepeated if more than one auxiliary field or command is used. Text will appear with the spreadsheets where

explanations are required. Use the Tab key, the arrow keys, or the mouse to navigate the input spreadsheet.Also, use the Plot command to review the work completed. To fix errors, navigate to the appropriate spreadsheet[PgUp] and change the entry.

CAESAR II automatically generates the From and To Nodes when you start a new spreadsheet. The cursor isinitially positioned in the From field. The From Node/ field should read 5 assuming the node increment is set to

5 in CONFIGURE/SETUP. If not, it can be reset using Edit-Insert. If it does not read 5, select the node number in

the white input box and type 5 over it. Now use the Tab, Enter or Down Arrow key to move to the next input

(the To Node in this case). Enter a 10 in the To field if one is not already there. All the remaining data entered onthis screen will now be associated with the first element from node 5 to node 10 or these two end points.




First Tutor Element Geometry and

Operating Conditions

Move down to the DY cell and enter the element length of 2 ft. by entering 2-, the "-"indicates feet. Node 10 marks the centerline intersection of the 8-in. main line with t

in. by-pass. In the next block, enter the nominal pipe size of 8 in. Note that after leavthis cell, the actual Outer Diameter (OD) replaces the nominal. Also with the standarwall thickness, the entered S

Next enter the operating conditions of Temperature (600ºF) and Pressure (30psi). Wethe units in our entries because

is replaced by the actual wall thickness. Enter the insula

thickness and corrosion allowance next. Note that fractions are allowed in these cellswell.

CAESAR II

At the top of the second column of this first spreadsheet, double -click the

already has the units’ information. Thecompleted first column of data displays in the figure to the left.

Displacem

check box to activate the Displacement Auxiliary Data area to the right, where you

enter the displacement information. For node 5 enter the Y and Z anchor displacemen0.077 in. and 0.046 in. respectively. These two numbers are calculated as the thermalgrowth of the pump discharge nozzle from the base support point. Note that the other

degrees of freedom must be entered as 0 without the entry of zero (or any other definof these boundaries), Node 5 would be free to move in these four directions. The figu

below shows the displacements entered correctly

Node 5 Tutor M odel Displacement Boundar y Condition



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Next we enter the pipe material by clicking the drop list to the right of the Material label and choose number 1Low Carbon Steel. Material properties will now be read in automatically from CAESAR II

Now double-click the

's material database.Ambient Elastic Modulus, Poisson’s Ratio, and Pipe Density will be filled in. The material number will also bereferenced to pick up the coefficient of expansion for the specified temperatures.

Allowable Stress check box to activate the Allowable Stress Auxiliary data area to the

right. The first 21 materials are Generic and do not have Allowable Stress values associated with them in thedatabase. However, the other materials in the list will also fill in the Allowable Stress values as found in thedatabase. The cold and hot allowable stresses (Sc and Sh) as defined by the piping code are entered for the typeof piping material to be analyzed. Here the cold allowable stress of 20,000 psi (don’t use commas) and the hotallowable stress of 17,300 psi are not extracted from the database so you must type these values. Exponentialformat may be used in these fields to simplify data entry and reduce mistakes. Click the drop list and select

B31.3 if it is not already there by default (The default code is defined in the Configure/Setup). The material property and allowable stress entries are shown in the following figure.




Node 10 is the intersection of the 8-in. and 6-in. lines. Thisintersection is constructed using an 8x6 welding tee. Piping codesrecognize the reduced strength of this piping component byincreasing the calculated stress at this point in the system. ForCAESAR II to include this stress intensification factor in the stress

calculation, the node must be identified as a welding tee. Firstdouble-click the SIFs and Tees check box to activate the SIFs and

Tees Auxiliary data area. Specify node 10 as our intersection nodeand select Welding Tee from the Type drop list. CAESAR II

With an insulation thickness specified,

will

calculate the SIFs at this intersection according to the piping codeselected (B31.3 in this case) so no more input is needed here.

CAESAR II will assume adensity for calcium silicate. For the purposes of this illustration this

value is entered manually as 11.5 lbf/ft3. The input is accepted as

lbf/in3 (use the F1 function key to confirm) so the entered value is

divided by 1728 in3/ft

3 to make this conversion. To clarify, type

11.5/1728 in the Insulation Density field and CAESAR II will

convert it. Another conversion capability is shown with the Fluid

Density cell. The commodity is specified as 80% the deadweight ofwater so enter 0.8SG in the field and CAESAR II

To define the next piece of pipe, press

will convert it tothe proper units.

ALT-C, select EDIT-CONTINUE, or click the Continue button on the farright-hand side of the toolbar.



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Note on this new spreadsheet that the To Node of the previous spreadsheet now appears as the From Node.Also, all the distributed data values (the information that carries on from one pipe to the next) remain on thisnew screen. The user only needs to add element length and any new boundary conditions or changes from the

previous element. The distributed data is re-entered only when they change value. Allowable Stress data carries

forward, even though the check box on subsequent spreadsheets is unchecked. Do not enable this box unless you

have a change in material, code, or temperature. Uniform Loads and Wind

This second element runs from the intersection point to the beginning of the check valve. This short run finishesout the welding tee and is bounded by nodes 10 and 15 as entered by

also carry forward without enablingthe check box. None of the other check boxes in the input carry forward.

CAESAR II. The length of this element is 7

in. in the Y direction so 7 is entered in the DY field. This data finishes the description of the second element.The entire spreadsheet for this second element follows.

Second Element Spreadsheet for Tutor



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The next node entered is located at the intersection of the vertical pipe centerline and the horizontal pipecenterline above it. This “construction point” at node 30 is not actually a node on the piping system. Anyadditional input specified at 30 and all output for node 30 will be located at the far weld point of the elbow,which connects the vertical and horizontal runs. The dimension of 10 ft. 2 in. runs from node 25 to node 30.

Enabling the Bend check box specifies the elbow. The Bend specification automatically generates additionalnodes around this elbow locating the near weld point and the bend midpoint (designated by the letter M). Node28 is listed in the auxiliary data field at angle 0 and the elbow midpoint is listed as node 29. These added nodeswill appear as output points and they may also be used to locate restraints. By default a long radius elbow (1.5nominal pipe size) will be added at the change in pipe direction. Users may also change the bend radius.

Bend Specification at End of Element Fr om 25 to 30 in Tutor




The hanger to be sized at this elbow is placed at node 28 in line with the vertical run of pipe. To enter the hangersizing information, double-click the Hanger check box. The Hanger Auxiliary Data area, like that shown in the

next figure, should be filled with node 28 entered as the Hanger Node. For this first pass through the analysis,the default settings will be used with no additional hanger design data. Press F1 on any of these input cells formore information. Here, the hanger will be chosen from Table 1 – the Anvil hanger catalog. Additionally, a

short-range spring will not be permitted at this point as the mid range spring will probably be cheaper.

Hanger Auxiliary Data Specification in Tutor



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The piping system continues on to the elbow at node 35. Again, the distance entered as CAESAR II input is thedistance between the intersections of the pipe centerlines; not the physical length of the straight piece of pipe

between the elbows. Here, -12 ft is in the X direction. This X run of pipe will finish off the elbow at 30 by

creating a 90-degree turn. Double click the Bend check box to generate the long radius elbow at 35 with the twoextra nodes. There is also a support at the far weld point of this bend. This far end of the bend is node 35 in themodel so the restraint is specified at node 35. This support will not allow the pipe to move downward, but itcannot prevent the pipe from moving upward. This non-linear restraint (a restraint whose stiffness, rather thanremaining constant, is a function of load or displacement) is entered as a +Y type. The +Y indicated that the

restraint supplies a positive Y (upward) load to the pipe; most users interpret the +Y as indicating the pipe is freeto move in the +Y direction. With no stiffness entered with this restraint, CAESAR II will set this to a very stiff(rigid) restraint; meaning that under any practical load, the pipe will not “push” the restraint down. Note that upto four restraints may be specified in this auxiliary data field. Except for the anchor designation, a restraint is a

vector. If there was a guide restraining lateral motion of node 35, an X restraint would also be defined here as thesecond restraint. Press F1 for more information about these restraint parameters.

Bend Specification and Restr aint Specification on Element from 30 t o 35 in Tut or

From the second elbow, the pipe runs in the Z direction for 18 ft where it terminates at the intersection with thevessel wall. As with the pump connection at node 5, node 40 is a satisfactory boundary for this model. The

thermal growth of the vessel at this point is calculated and entered as displacements of node 40.

Displacement Boundar y Conditions Simulating Vessel Ther mal Gr owth at Node 40 in Tutor .




The model now returns to the 6-in. by-pass piping around the 8-in. check valve above the pump. The welding teenodes of 10 and 25 will be completely defined as reducing tees when these 6-in. piping elements are modeled.

The figure below shows the changes required to start the 6-in. line, which is explained here.

The input processor automatically shifts the previous To Node to the current From Node. Since the model is no

longer continuing from node 40, the From Node must be changed here to 10 and the To Node is set to 605 asthe 600 series of node numbers will indicate 6-in. pipe. The X length of -2 ft is measured from the 8-in.centerline to the centerline of the vertical 6-in. line. Diameter is entered as 6 and Wt/Sch is entered as S . Anelbow is specified at node 605 by double-clicking the Bend check box. Note that CAESAR II automaticallygenerates a long radius elbow for this 6-in. line. This elbow is flanged on one end. This flange acts like a

stiffening ring, which reduces the bending flexibility of the elbow. This characteristic of flanged elbows isaddressed by the piping codes through a modification of the flexibility factor and stress intensification for theelbow. To include this effect, select Single Flange from the Type drop list in the Bend Auxiliary data area. A

simple by-pass piping, the inclusion of flange stiffening, is probably insignificant and can be ignored.

Bypass Inputs in Tutor



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The 6-in. piping continues up to node 610, which marks the beginningof the gate valve. The distance between the horizontal centerline(nodes 30 to 605) and the bottom of the valve is 9 in. in the Ydirection. This 9-in. specification puts node 610 at the far end of the

bend defined on the previous screen. The input locations of nodes 605and 610 are coincident, which would produce a zero length element.

CAESAR II inserts a length for this element 605-610 equal to 5% of the bend radius In this case, the value is 0.45 in. This 5% default value,

which can be changed in the CAESAR II

configuration, prevents thegeneration of a zero length element.

The next element is the 6-in. 150-psi class,flanged gate valve running from 610 to 615.Use the Valve/Flange database (with thecommand Valve) for this rigid element. Selectthe 150 psi flanged gate valve (default) and

click OK. CAESAR II will return from thedatabase with rigid Y run, 17.625 in. long,

weighing 225 pounds. As with the 8-in. checkvalve, the deadweight and length of the

attached flanges should be included in thisanalysis. (Use the NOFLG End Type

150 Flanged Gate Valve Selected from the CADWorx Valve/Flange Database

if you

do not want these included.)

Resulting CAESAR II Element Definition for the 150 Flanged Gat e Valve




The element from 615 to 620 is the length required to bring the pipe up level with the intersection at node 25.This distance is easy to find by choosing the Distance command from the toolbar or from the menu with EDIT- DISTANCE. The Y-distance in this case between 615 and 25 is 15 in., so this distance is input as DY on the

spreadsheet for 615 to 620. Also a bend must be specified here since the next element will connect the currentelement to the intersection at node 25.

The Y value of the distance between nodes 615 and 25 gives us the dimension for the element from 615 to 620.

For the element running from 620 to 25 we know from the previous Distance command that it is 2 ft in the x-

direction. But imagine for a moment that we did not have this information. In this case we can use the Close

Loop command EDIT- CLOSELOOP and CAESAR II will calculate this dimension and enter it into the appropriate

DX, DY, and DZ fields. First create the spreadsheet and enter 25 for the To Node. Then perform the Close Loop command. DX will now have a value of 2 ft.



7-20 Tutori al A

The close loop on element 620 to 25 will fill in the distances for DX, DY, and DZ

Input Review

fields.

Two commands are available on any input screen to review the data: Plot and List. While the input can bechecked by paging through each input screen, these commands are useful in confirming and/or editing the entiremodel. The use of these commands will be demonstrated in this section. By default a plot of the model is

displayed to the right of the piping input spreadsheet. The plot area can be increased if the piping input pane is

closed. To close the piping input, click the button in the upper right corner of the spreadsheet. To display

the Classic Piping Input spreadsheet and the model side by side, click the Classic Piping Input tab that

displays in the upper left corner of the spreadsheet and then click the button twice. The volume plot of thecurrent piping system is shown; available toolbar buttons and menu commands can be used to perform various

functions. To display the node numbers press the letter N on the keyboard or click the button on the toolbar.The following figure shows the tutor model with the node numbers displayed.




A few notes about the commands may be useful here; Use the arrow keys to rotate the plot. Users may also usethe arrow keys or mouse to pan the plot after clicking the Pan button. Scrolling the mouse will zoom the model

and pressing the center mouse button will pan the plot. Clicking the right mouse button on the display andclicking OPERATORS-P AN from the pop-up menu provides an alternative method of panning the plot. The model

will then follow the mouse cursor within the display. The plus sign (+) zooms in and the minus sign (-) zooms

out. There are toolbar buttons and menu items to alter the pan view and to display element and restraintinformation on the plot. Users are encouraged to use these different items to become familiar with them. To

reset the plot to the default use the button or VIEW/RESET. To print a copy of the display choose FILE-PRINTor click the Print button.

Note: Because the graphics are included in the Input Processor the graphic must be clicked to set the focus prior

to printing.

Node Number s Displayed on the Plot in Tutor



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The V key toggles different views. The Volume Plot shown below is especially useful for larger models as ituses less of the computer's resources.

Volume Plot Showing Spring Hanger and Support L ocations in Tutor

The illustration below shows a view down the Z axis with a zoom and pan to show the pipe valves. This volume plot shows the nodes and identifies the tees.

Volume Plot View Along Z-Axis Showing Nodes, Tees, and Displacements in Tutor



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Performing the Static Analysis

After error checking the model, review the load cases. From the Edit menu highlight Edit Static Load Cases or

click to enter the Load Case Editor. CAESAR II will begin with a standard set of load cases based upon the piping code selected and the loads defined in input. For the job Tutor, size the hanger before the standard

structural and stress analyses are performed. This hanger sizing algorithm requires two analyses before thestandard three cases are analyzed. The five recommended load cases are shown below. From the menu that

appears in the following figure, select the option that recommends the load cases.

Load Case Editor with Two Hanger Design Cases and the Standar d Thr ee Load Cases for Tutor

CAESAR II creates load sets to analyze the operating conditions of the piping system and the installed conditionsof the piping system. The operating condition for this analysis consists of the deadweight of the pipe, its contents

and insulation, the design temperature and pressure, and the pre-load on the just-selected hanger at node 28. Theinstalled condition includes the deadweight and hanger pre-load. In addition to these structural analyses, certainstress conditions must be addressed. For the piping code used here, the sustained and expansion stresses must becalculated. Sustained stresses include deadweight, pre-loads and pressure. Sustained stresses can be taken fromthe installed condition analysis if the pressure loads are included. CAESAR II will include the pressure term in the

installed case since pressure, in most cases, has no impact on the structural loads on the piping. With theinstalled case structural analysis also serving as the sustained case stress analysis, no additional load case must

be added to calculate the sustained stresses. Expansion stresses reflect the change in system position from itsinstalled position to its operating position. Because of system non-linearity this change in position cannot be

determined by analyzing thermal loads alone. By default CAESAR II will construct a third load case to calculatethe expansion stress (range). This case is not, strictly speaking, a third, complete analysis of the system butinstead a product of the operating and installed structural analyses already performed. The difference in systemdisplacements between these two cases is the displacements stress range from which the expansion stresses are




calculated. The third class of stress in piping – occasional stresses (as opposed to expansion and sustained) – isnot included in the recommended analyses and must be specified by the user. Likewise, FATigue stress cases are

provided only when specifically required by the active piping code (TD/12, for example).

For most systems, the recommended load cases are exactly what the user wishes to analyze. Case #1 calculates

the deadweight carried by the proposed spring at node 28. Case #2 also calculates only one number, the verticaltravel of the proposed spring. All the load categories, which compose the operating load case, are used for thisanalysis. These are deadweight, displacements, thermal set 1, and pressure set 1. With these two numbers - theload carried by the hanger and the amount of travel it must accommodate CAESAR II

Case #3 is the operating Hanger Load case. It is identical to case #2 but has the sized hanger pre-load included inthe category (H). This analysis will produce the operating forces and moments on the supports, and the

deflections of all points in the system. Case #3 is a structural analysis case and not a B31.3 stress analysis case.The refining piping code does not recognize pipe stress in the operating condition as a test for system failure and

does not establish a limit for this state of stress. Case #4 is both a structural and stress case. By eliminating the

(assumed) thermal effects (D1+T1), the analysis is of the cold system. By including pressure (P1), this case alsohas the necessary components to be used to report the system’s sustained stresses. Case #5 (L3-L4) is analgebraic combination of two basic load cases. The displacements of case #4 are subtracted from thedisplacements of case #3 to produce these results. This case develops the displacement range of the system in its

growth from the installed position to the operating position. This displacement range is used for the calculationof the system’s expansion stresses.

will enter the Anvil catalogand select the appropriate spring. This spring and its proper pre-load are installed in the model for the remaining

analyses.

To proceed with the analysis, click File-Analyze or click the button. The program continues with the data processing by building, sorting, and storing the equation (matrix) data for the system and the basic load cases.This process may be terminated at any time by clicking Cancel. When this is done, the CAESAR II Solution

Module is entered.

CAESAR II will analyze the four basic loads (hanger design, operating, and installed) before leaving this screen.At this point the solution screen is replaced with messages concerning the post processing of this data. Thedisplacement results of cases 3 and 4 are used with the element stiffness matrices to calculate the forces,moments, and stresses throughout the system. The difference between these two sets of displacements is used toestablish the displacement range of the piping system as defined in load case #5. This new displacement set is

similarly used to calculate forces, moments, and stresses. At the completion of this step, all the results are loadedinto the binary data file Tutor._p and the CAESAR II output processor window is displayed so that output for this

job may be reviewed. The “._p” file can only be examined through the output processor. The analysis need not be rerun to review these results at a later time, instead, the optionOUTPUT-STATICS from the Main Menu may be

used to bring up the output from the TUTOR._P file.



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Reviewing the Static Results

Whether entering the output processor directly from the static analysis or through the Main Menu, the Output

Window displays.

Static Output Processor

Usually the first look at output is to verify that the piping model is responding as expected. Checking deflectionsand restraint loads in the operating and installed cases should quickly uncover any major problems with the

system layout or input. If there are unusual results, the input should be re-examined for correctness. If the outputverifies the model, the results can be used to collect pipe stresses, support and equipment loads, and any otheruseful data found in the output. This information is useful in documenting a good piping design ortroubleshooting an inadequate one.




A good view of the operating displacements of this piping system is available by selecting the (OPE) load case

then clicking the button. The image shown in the following figure will appear on the screen.

Tutor Outp ut Plot



7-28 Tutori al A

As in other CAESAR II windows both the toolbar buttons and menu items may be used to select display options.From the menu, select SHOW-DISPLACEMENT-DEFLECTEDSHAPE. The plot will show the centerline plot along with anormalized deflected shape of the system in the operating condition. This screen is shown in the next figure.

Displaced Shape Plot

When finished viewing the plotted output for the operating case, change the case to Sustained in the drop list onthe left of the second toolbar. Select SHOW-STRESS-OVERSTRESS and note that there is no over-stressed points existin the system. Reset the plot and select SHOW-STRESS-SYMBOL-CODE to display the code defined stresses

throughout the system. The stress symbols will appear on the screen and locate the highest stress points in the

system. Now select SHOW-STRESS-M AXIMUM to list the stress values on the plot; use the Enter key to list thestresses one at a time starting with the highest. The node number is shown in parenthesis following the stress

value placed on the screen and the element containing this node is highlighted. Here, the highest (first) sustainedstress listed is at node 40 (nozzle to vessel connection) with a value of 160859 psi.




For a quick review of the stresses as well as the displacements and restraint loads the Element Viewer can be

enabled by clicking the button on the toolbar. This information displays in the next figure. Return to theoutput processor menu by clicking Exit or FILE-EXIT.

Output Plot with Maximum Str ess Point Revealed

For a quick look at the selected hanger data, select Hanger Table with Text from the General ComputedResults Column in the main Output Processor. The program reports the Anvil Fig. B-268 Size 10 springselected at node 28. This selection is based on the values found in the first two analyses (both provide no load

case reports in the output processor) – the expected hot load for the proposed support at node 28 and the thermalgrowth of node 28 (1220 lb. and 0.750 in., respectively). Return to the Output Menu and select only the

operating load case and Displacements and Restraint Summary. The restraint loads at nodes 5 and 60 will becompared to the pump and vessel load limits. Return to the Output Menu and now select the installed case (turn

off 3 and turn on 4) to examine the installed condition of the piping system. (Both the operating and installedcases could be reviewed together by having both 3 and 4 highlighted at the same time.) Now highlight thesustained and expansion cases (4 and 5) and Stresses. Each stress report will begin with a summary stating thatthe code stresses are below their allowable stress. In the table that follows the summary, the stresses will bedisplayed for each node in the system. These nodes will be listed in pairs with their associated element. Note the

last column lists the ratio of actual stress to allowable stress in terms of percentage.




Static Analysis Output Listing

The following is a CAESAR II tutorial output report:

Hanger Report

Note

The hot load of 1222 lbf. was calculated in the initial weight run (load case #1) with a rigid Y restraint installedat node 28. The load on the restraint was 1222 lbf.

- The output listed in the example includes significant output only.

- Notes, which discuss the results are included with each report.- The reports included in this output are Complete Hanger Report, Operating Case Displacement Report,

Installed (Sustained) Case Displacement Report, Operating & Installed Restraint Summary, Sustained StressSummary and Stress Report, and the Expansion Stress Summary and Stress Report. (Stresses in the operating

condition are not used in B31.3 analyses)

A 1222 lbf. +Y load replaced the rigid Y restraint at 28 and then an operating case was analyzed (load case #2). Node 28 moved 0.750 in. in the +Y direction in this analysis.




Sustained Displacements

Note: Look at the zero position of nodes 5 and 40. When the imposed displacements are not included in the

analysis, the node is fixed with zero movement in each of the defined directions.



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Restraint Summary for the Operating and Sustained Cases

This restraint report lists the piping forces and moments on the restraint; not the restraint loads on the piping.The loads at node 5 are the nozzle loads and can be used without sign change to check the API 610 allowable

loads. Loads for node 40 may be used to check the vessel stresses due to the nozzle loads.

The loads at 28 show the operating load and the actual installation load (with contents) for the selected spring.

Note how the spring carries the designed load of 1222 pounds in the operation condition.

The +Y restraint at node 35 shows it is nonlinear nature. In the cold condition, the restraint is active. As the

piping moves to the hot position, it disengages from the support. Refer back to the displacement reports toconfirm that the Y displacement is 0.0 in the installed (sustained) condition and +Y in the operating condition.




Sustained Case Stress Report - Summary Information

The summary shows that the sustained stresses throughout the system are below their allowable values. Thesustained stress closest to its allowable limit is at the vessel node, 40.



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For the previous stress detail report note the application of the tee and bend stress intensification factors. The teeat 25 has SIFs other than 1.00 for all three listings: 25 to 28, 20 to 25, and 25 to 620. Bend SIFs are applied onlyon the bend side of the node compare node 28 on 25-28 and 28-29. No stresses are listed for rigid elements as

no valid moment of inertia is provided for these elements.



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For the stress detail report previous: Compare the bend side of 30 with the straight side of 30; the SIF doublesthe calculated stress. Also note the changing allowable stress. This is the result of applying an allowable stress,which takes credit for “unused” stress in the sustained case.




Conclusions

The review of piping stresses shows that the piping has adequate wall thickness and support to keep within thesustained allowable stress, and also enough flexibility to remain below the expansion allowable stress limit. A

quick review of the system displacements does not reveal any interference problems from pipe expansion.Equipment loads must still be checked to ensure a safe and effective design. The pump loads at node 5 may becompared to the API (American Petroleum Institute) Standard 610 (Seventh Edition, February 1989) -Centrifugal Pumps for General Refinery Service. The nozzle loads, too, can be compared to the allowedmaximum limits. The nozzle loads can be translated into local stresses using Welding Research Council

Bulletins 107 or 297 - Local Stresses in Cylindrical Shells Due to External Loadings on Nozzles (WRC 107) orit's Supplement (WRC 297). These local stresses can then be compared to allowable stress values established in"ASME Section VIII Division 2 Appendix 4 - Mandatory Design Based on Stress Analysis". Since the loads onthese boundary conditions are related to the piping system layout, the piping system cannot be properly approveduntil these load limits are also verified. These verifications will be done in the following chapter.

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