Good Book Load Case Editor

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M

echan

ical

En

gineering

News

FOR THE POWER,

PROCESS AND

RELATED INDUSTRIES

The COADE Mechanical Engineering

News Bulletin is published twice a yearfrom the COADE offices in Houston,Texas. The Bulletin is intended to provideinformation about software applicationsand development for MechanicalEngineers serving the power, process andrelated industries. Additionally, the Bulletinserves as the official notificationvehicle for software errors discovered inthose Mechanical Engineering programsoffered by COADE.

2001 COADE, Inc. All rights reserved.

V O L U M E 3 0 J A N U A R Y 2 0 0 1

Whats New at COADE

PVElite Version 4.10 New Features ............... 1

CAESAR II Version 4.30 New Features......... 4

TANK Version 2.20 Released ...................... 11

The New Pipe Stress Seminar Format......... 11

Technology You Can Use

Sustained Stresses ...................................... 12

Using the New CAESAR II Static Load Case

Builder ...................................................... 19

PC Hardware for the Engineering User

(Part 30) ................................................... 25

Program Specifications

CAESAR II Notices ...................................... 26

TANK Notices ............................................... 26

CodeCalc Notices ........................................ 27

PVElite Notices ............................................ 27

CAESAR IIVersion 4.30

New Features

>see story page 4

Sustained

Stresses

>see story page 12

Using the New

CAESAR II StaticLoad Case

Builder

>see story page 19

Article Here

PVElite Version 4.10 New Features(by: Scott Mayeux

PVElite Version 4.10 contains many new exciting additions. A brief list o

the enhancements is shown in the table below. This article will discuss a few

of these new features and how they may impact vessel designs.

ASME 2000 addenda has been incorporated

Provision to use the 1999 year material database

TEMA and ASME tubesheet programs updated to perform multiple load cases

Separate entry of m and y factors for partition gaskets

User bolt loads in the tubesheet programs

Simultaneous Corroded and UnCorroded thick expansion joint calculations

ASCE 98 wind code added

Rigging analysis with graphical results processor added

The input ( thicknesses, rings, repads ) can now be updated by the analysis

program

The 3-D viewer now has a transparency option

Ladder information is now collected

User time history input for IS-893 RSM

As always there have been changes to ASME VIII Division 1 and the materia

database(s). Typically, new materials are added and obsolescent materials are

withdrawn from the Code. In this revision to the program we have of course

updated the material tables and now offer the option of using the current (2000)

addenda, the pre-1999 addenda (lower allowable stresses) or the 1999 stress

tables. The option that allows this is found in theTools->Configurationdialog

Another major change was made to both the ASME and TEMA tubeshee

programs. ASME Appendix AA was modified substantially for 2000. The

new changes themselves do not typically generate answers that are significantly

different from the previous year addenda. While the alterations were being

I N T H I S I S S U E :


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COADE Mechanical Engineering News January 20

2

made, we added new functionality in the way of multiple load cases.

If informed to do so, either of the ASME or TEMA tubesheet

programs can run up to 16 load cases for fixed tubesheet exchangers.

These load cases involve different combinations of temperature,

pressure (internal and external) as well as corrosion allowance. The

generated output for these 16 cases is reduced to a mere 2 or 3

pages. Previously, this could have generated up to 60 pages. Asample table of results and the dialog used to control the output is

shown below:

Fixed Tubesheet Required Thickness per TEMA 8th Edition:

Thickness Reqd ----- P r e s s u r e s Case Pass/

Case# Tbsht Extnsn Pt' Ps' PDif Type Fail----------------------------------------------------------------------1c 2.551 0.879 49.71 0.00 0.00 Fvs+Pt-Th+Ca Ok2c 0.850 0.879 0.00 -2.48 0.00 Ps+Fvt-Th+Ca Ok3c 2.610 0.879 49.71 -2.48 0.00 Ps+Pt-Th+Ca Fail4c 0.770 0.879 0.00 0.00 -0.48 Fvs+Fvt+Th+Ca Ok5c 2.550 0.879 49.71 0.00 -0.48 Fvs+Pt+Th+Ca Ok6c 0.850 0.879 0.00 -2.47 -0.48 Ps+Fvt+Th+Ca Ok7c 2.609 0.879 49.71 -2.47 -0.48 Ps+Pt+Th+Ca Fail8c 0.770 0.879 0.00 0.00 0.00 Fvs+Fvt-Th+Ca Ok1uc 1.662 0.879 19.81 0.00 0.00 Fvs+Pt-Th-Ca Ok2uc 1.279 0.879 0.00 13.43 0.00 Ps+Fvt-Th-Ca Ok3uc 1.662 0.879 19.81 13.43 0.00 Ps+Pt-Th-Ca Ok4uc 1.733 0.879 0.00 0.00 -49.37 Fvs+Fvt+Th-Ca Ok5uc 1.733 0.879 19.68 0.00 -49.37 Fvs+Pt+Th-Ca Ok6uc 1.954 0.879 0.00 13.35 -49.37 Ps+Fvt+Th-Ca Ok7uc 1.954 0.879 19.68 13.35 -49.37 Ps+Pt+Th-Ca Ok8uc 0.750 0.879 0.00 0.00 0.00 Fvs+Fvt-Th-Ca Ok----------------------------------------------------------------------Max: 2.610 0.879 in.

Given Tubesheet Thickness: 2.5625 in.

Note:Fvt,Fvs - User-defined Shell-side and Tube-side vacuum pressures or 0.0.

Ps, Pt - Shell-side and Tube-side Design Pressures.Th - With or Without Thermal Expansion.Ca - With or Without Corrosion Allowance.

Tube and Shell Stress Summary: Shell Stresses Tube Stresses Tube Loads Pass

Case# Ten Allwd Cmp Allwd Ten Allwd Cmp Allwd Ld Allwd Fail-1c 33 15900 0 -4968 10762 13500 0 -5458 1161 1020 Fail2c 0 15900 -290 -4968 1870 13500 0 -5458 202 1020 Ok3c 33 15900 -290 -4968 12633 13500 0 -5458 1363 1020 Fail4c 28 15900 0 -4968 0 13500 -116 -5287 0 1020 Ok5c 45 15900 0 -4968 10765 13500 -116 -5287 1162 1020 Fail6c 28 15900 -289 -4968 1870 13500 -116 -5287 202 1020 Ok7c 45 15900 -289 -4968 12634 13500 -116 -5287 1363 1020 Fail8c 0 15900 0 -4968 0 13500 0 -5458 0 1020 Ok

1uc 3389 15900 0 -5038 3467 13500 0 -5458 374 1020 Ok2uc 1507 15900 0 -5038 0 13500 -1975 -5458 213 1020 Ok3uc 4896 15900 0 -5038 3467 13500 -1975 -5458 374 1020 Ok4uc 2771 15900 0 -5038 0 13500 -11927 -5287 0 1020 Fail5uc 4473 15900 0 -5038 3436 13500 -11927 -5287 371 1020 Fail6uc 2771 15900 0 -5038 0 13500 -13885 -5287 211 1020 Fail7uc 4903 15900 0 0 3436 13500 -13885 -5287 371 1020 Fail8uc 0 15900 0 -5038 0 13500 0 -5458 0 1020 Ok-

MAX RATIO 0.308 0.058 0.936 2.627 1.337

Additionally, the thick expansion joint program can now a

accommodate calculations in both the corroded and uncorrod

conditions in the same run. The ability of the program to prov

this functionality will potentially reduce input errors.

Also in the Component Analysis program (CodeCalc), we ha

allowed the entry for separate m and Y factors as well and sketand column information for all components that have option

entries for partition gasket information. User defined bolt load d

is also available in the tubesheet modules.

In the main analysis section ofPVElite there have also been ma

changes. One time saving change is that after the analysis (in desi

mode) has changed any data values such as thicknesses, stiffeni

rings, basering data or reinforcing pad information, the input can

automatically updated by the program at the users request.

illustrate this, review the model below. We have requested t

program to add angle type stiffeners to this vessel.

After the program has generated the new input, it will ask f

confirmation to use the new data.


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January 2001 COADE Mechanical Engineering News

3

After accepting the changes, here is how the model appears.

Other new items include the option of entering ladder data in the

platform dialog. As shown below, the 3-D graphics have also been

updated to draw the ladders. Note that the transparency option has

been turned on for the shell and cone elements.

Another major addition to this version is that the program can nowperform a rigging analysis. This is the computation of bending and

shear stresses in a vessel when it is being lifted from the horizonta

position. The rigging analysis requires that the location of the lugs

be entered in as well as the impact factor for lifting. The impac

factor accounts for how rough the vessel is lifted. This value

generally lies between 1 and 2, but values as high as 3.0 can be used

If the impact factor is less than 1.0 or the lug distances are not

defined, the program will not perform the analysis. The main

objective is to determine if the stress levels are excessive during

lifting. The program computes a combined bending plus shea

stress check. The result of this check should be less than or equal to

1.0. The result of a typical rigging analysis is shown below.

RIGGING ANALYSIS

Total weight of the vessel (No liquid) Twt 92238.39 lb.Impact weight multiplication factor Imp 1.50Design lifting weight, DWT = Imp * Twt 138357.58 lb.Elevation of the tail lug 0.50 ft.Elevation of the lifting lug 70.00 ft.Length of element used for the analysis, INC 1.00 ft.Overall height (node to node) 94.77 ft.Elevation of the vessel center of gravity 44.26 ft.

Design reaction force at the tail lug 51250.46 lb.Design reaction force at the lifting lug 87107.12 lb.

Critical values:Max stress Elevation Allowables

psi ft. psi|||Bending | -3772.13 | 30.38 | 14518.90 (UG-23)Shear | -470.55 | 69.95 | 11280.00 (0.4*Sy)|||

AISC Unity Check was 0.2600 at 29.44 ft. (must be


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The graph shown below depicts the combined bending plus shear

stress. The graph tool is invoked from the main screen after the

rigging results data file has been generated. The arrows on the

toolbar switch between the different graphs.

Another update to version 4.10 came in the form of the ASCE 98

wind design code. This code is nearly identical to its predecessor,

ASCE 95. However, the computation of the gust response factor

for both static and dynamic cases has been slightly altered. New

values of the dynamic gust factor have been found to be slightly

lower than those computed by the previous edition of ASCE. The

static gust factor is slightly higher than previous values.

There are several other enhancements to PVElite that have not beenmentioned here. The updates to the user guide will contain more

information. This product is scheduled for an early January 2001

release date.

CAESAR II Version 4.30

New Features(by: Tom Van Laan & Richard Ay)

CAESAR II Version 4.30 is a major release providing users withsignificantly enhanced analysis capabilities, as well as additional

user interface improvements. A list of the major additions and

improvements for Version 4.30 are listed in the table below.

CAESAR II Version 4.30 Features

Improved 3-D graphics

New Load Case Editor, offering different combination methods, load scale factors, andmore

Undo/Redo in the input module

Z-axis vertical

MS WORD as an output device

Code Compliance report (statics only)

Load Case Report

ODBC/XML wizard interface for CAESAR II input and output

Graphics in the WRC 107 Module

Animated Tutorials

New Configuration Options

User-Configurable Toolbar in Input Module

Updated piping codes: B31.1, B31.3, ASME NC, ASME ND

Graphics Improvements:

The 3D graphics have been improved to provide more informati

to the user. These improvements include:

When the button is in selected mode, the user can add annotatio

with leader lines, to the graphics.

Font type, size and color, may be changed for the annotati

through use of the button, followed by the Fonts tab.

Clicking the or the buttons (or using the Options-Diamet

or Options-Wall Thickness menu commands) highlights the pipi

model, by color, according to its diameters or wall thickness

respectively.

Three new standard views (YX, ZX, and ZY) have been adde

Standard views are accessed by the , , , , , , and

(isometric) buttons.

Changes to graphics settings are restored whenever users exit a

return to the graphics view. Alternatively, the user may se

standard setup to be always restored upon entering graphics. T

is done through the use of the button, followed by the U

Options tab.

The CAESAR II Animation module has been converted to u

these new 3D graphics. Zooming, rotating, and panning can now

easily controlled via the mouse, in exactly the same manner as t

input graphics.

Static Load Case Editor Enhancements:

The CAESAR II Static Load Case editor now offers much mo

user control. New features include use of scale factors wh

including load components in load cases or previous load cases

load combinations; user-defined load case names; user-controll

combination methods (for combination cases only); and grea

user control of what output data gets produced.


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Note that previous load cases are now referred to, in combination

cases, as L1, L2, L3, etc. (Load Case 1, Load Case 2, Load Case 3,

etc.) rather than DS1, FR2, ST3, etc., since it is no longer meaningful

to talk about combinations being done at the displacement level,

force level, or stress level.

Scale factors for load components and previous load cases incombinations: When building basic load cases, load components

(such as W, T1, D1, WIND1, etc.) may now be preceded by scale

factors such as 2.0, -, 0.5, etc. Likewise, when building combination

cases, references to previous load cases may also be preceded by

scale factors as well. This provides the user with a number of

benefits:

1) In the event that one loading is a multiple of the other (i.e., Safe

Shutdown Earthquake being two times Operating Basis Earthquake,

only one loading need be entered in the piping input module; it may

be used in a scaled or unscaled form in the Load Case Editor.

2) In the event that a loading may be directionally reversible (i.e.,wind or earthquake), only one loading need be entered in the piping

input module; it may be used preceded by a + or a to switch

directionality.

Load Rating Design Factor (LRDF) methods may be implemented

by scaling individual load components by their risk-dependent

factors, for example:

1.05W+1.1T1+1.1D1+1.25WIND1

User-defined load case names: CAESAR II now offers a second

tab on the Static Load Case screen Load Case Options. Among

other features, this screen allows the user to define alternative, moremeaningful Load Case names, as shown in the figure.

These user-defined names appear in the Static Output Processor in

the Load Case Report (for more information, see below), and may

also be used in place of the program load case names anywhere in

the Static Output Processor, by activating the appropriate option

therein.

Note, these load case names may not exceed 132 characters inlength.

User-controlled combination methods: For combination cases

CAESAR II now offers the user the ability to explicitly designate

the combination method to be used. Load cases to be combined are

now designated as L1, L2, etc. for Load Case 1, Load Case 2, etc.

with the combination method selected from a drop list on theLoad

Case Options tab. The available methods are:

Algebraic: This method combines the displacements, forces

moments, restraint loads, and pressures of the designated load

cases in an algebraic (vectorial) manner. The resultant forces

moments, and pressures are then used (along with the SIFs andelement cross-sectional parameters) to calculate the piping

stresses. Load case results are multiplied by any scale factor

(1.8, -, etc.) prior to doing the combination. (Note that the

obsolete CAESAR II combination methods DS and FR used

an Algebraic combination method. Therefore, load cases buil

in previous versions of CAESAR II using the DS and FR

methods are converted to the Algebraic method. Also, new

combination cases automatically default to this method, unless

specifically otherwise designated by the user.) Note that in the

load case list shown in the figure, most of the combination

cases typically are built with the Algebraic method. Note tha

Algebraic combinations may be built only from basic (i.e.

non-combination) load cases or other load cases built using theAlgebraic combination method.

Scalar: This method combines the displacements, forces

moments, restraint loads, and stresses of the designated load

cases in a Scalar manner (i.e., not as vectors, but retaining

consideration of sign). Load case results are multiplied by any

scale factors prior to doing the combination (for example, for a

negative multiplier, stresses would be subtractive). This method

might typically be used when adding plus or minus seismic

loads to an operating case, or when doing an Occasional Stress

code check (i.e., scalar addition of the Sustained and Occasiona

stresses). (Note that the obsolete CAESAR II combination

method ST used a Scalar combination method. Therefore

load cases built in previous versions ofCAESAR II using the

ST method are converted to the Scalar method.)

SRSS: This method combines the displacements, forces

moments, restraint loads, and stresses of the designated load

cases in a Square Root of the Sum of the Squares (SRSS

manner. Load case results are multiplied by any scale factors

prior to doing the combination; however, due to the squaring


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used by the combination method, negative values vs. positive

values will yield no difference in the result. This method is

typically used when combining seismic loads acting in

orthogonal directions.

Abs: This method combines the displacements, forces,

moments, restraint loads, and stresses of the designated loadcases in an Absolute Value manner. Load case results are

multiplied by any scale factors prior to doing the combination;

however, due to the absolute values used by the combination

method, negative values vs. positive values will yield no

difference in the result. This method may be used when doing

an Occasional Stress code check (i.e., absolute summation of

the Sustained and Occasional stresses). Note that the Occasional

Stress cases in the figure are built using this method.

Max: For each result value, this method selects the

displacement, force, moment, restraint load, and stress having

the largest absolute value from the designated load cases; so no

actual combination, per se, takes place. Load case resultsare multiplied by any scale factors prior to doing the selection

of the maxima. The report shows the signed value. This

method is typically used when determining the design case

(worst loads, stress, etc.) from a number of loads. Note that the

Maximum Restraint Load case shown in the figure uses a

Max combination method.

Min: For each result value, this method selects the displacement,

force, moment, restraint load, and stress having the smallest

absolute value from the designated load cases; so no actual

combination, per se, takes place. Load case results are

multiplied by any scale factors prior to doing the selection of

the minima.

SignMax: For each result value, this method selects the


the largest actual value, considering the sign, from the designated

load cases; so no actual combination, per se, takes place.

Load case results are multiplied by any scale factors prior to

doing the selection of the maxima. This combination method

would typically be used in conjunction with the SignMin

method to find the design range for each value (i.e., maximum

positive and maximum negative restraint loads).

SignMin: For each result value, this method selects the


the smallest actual value, considering the sign, from the

designated load cases; so no actual combination, per se,

takes place. Load case results are multiplied by any scale

factors prior to doing the selection of the minima. This

combination method would typically be used in conjunction

with the SignMax method to find the design range for each

value (i.e., maximum positive and maximum negative restraint

loads).

User control of output availability:

CAESAR II allows the user to specify whether any or all of the lo

case results are retained for review in the Static Output Process

This is done through the use of two controls found on theLoad C

Options tab. These are:

Output Status: This item controls the disposition of the ent

results of the load case the available options are Keep

Discard. The former would be used when the load case

producing results that the user may wish to review; the lat

option would be used for artificial cases such as the prelimin

hanger cases, or intermediate construction cases. For examp

in the load list shown in the figure, the Wind only load ca

could have been optionally designated as Discard, since it w

built only to be used in subsequent combinations, and has

real value as a standalone load case. Note that load cases us

for hanger design (i.e., the weight load and hanger travel ca

designated with the stress type HGR) must be designated

Discard. Note that for all load cases created under previoversions ofCAESAR II, all load cases except the HGR ca

are converted as KEEP; likewise the default for all new ca

(except for HGR load cases) is also KEEP.

Output Type: This item designates the type of results that

available for the load cases which have received a KEE

status. This could be used to help minimize clutter on t

output end, and ensure that only meaningful results are retain

The available options are:

Disp/Force/Stress: This option provides displacemen

restraint loads, global and local forces, and stress

Example: This would be a good choice for Operaticases, when designing to those codes which do a co

check on Operating stresses, because the load case wou

be of interest for interference checking (displacement

restraint loads at one operating extreme (forces), and co

compliance (stresses). Note that basic (non-combinatio

and DS combination load cases developed under previo

versions of CAESAR II are converted with this Di

Force/Stress type. Likewise, new load cases created a

default to this Disp/Force/Stress type.

Disp/Force: This option provides displacements, restra

loads, and global and local forces. Example: This wou

be a good choice for Operating cases, when designing t

code which does not do a code check on Operating stress

because the load case would be of interest for interferen

checking (displacements) and restraint loads at one operati

extreme (forces).

Disp/Stress: This option provides displacements a

stresses only.


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Force/Stress: This option provides restraint loads, global

and local forces, and stresses. Example: This might be a

good choice for a Sustained (cold) case, because the load

case would be of interest for restraint loads at one operating

extreme (forces), and code compliance (stresses). Note

that FR combination load cases developed under previous

versions of CAESAR II are converted with this Force/Stress type.

Disp: This option provides displacements only.

Force: This option provides restraint loads, and global and

local forces only.

Stress: This option provides stresses only. Example: This

would be a good choice for a Sustained plus Occasional

load case (with Abs or scalar combination method), since

this is basically an artificial construct used for code stress

checking purposes only. Note that ST combination load

cases developed under previous versions ofCAESAR IIare converted with this Stress type.

Undo/Redo in the input module:

Any modeling steps done in the CAESAR II piping input module

may be undone, one at a time, using the Undo command, activated

by the button on the toolbar, theEdit-Undo menu option, or the

Ctrl-Zhot key. Likewise, any undone steps may be redone

sequentially, using the Redo command, activated by the button

on the toolbar, the Edit-Redo menu option, or the Ctrl-Yhot key.

An unlimited number of steps (limited only by amount of available

memory) may be undone.

Note that making any input change while in the middle of the undo

stack of course clears the stack of redoable steps.

Z-axis vertical:

Traditionally, CAESAR II has always used a coordinate system

where the Y-axis coincides with the vertical axis. In one alternative

coordinate system, the Z-axis represents the vertical axis (with the

X-axis chosen arbitrarily, and the Y-axis being defined according to

the right-hand rule). CAESAR II now gives the user the ability to

model using either coordinate system, as well as to switch between

both systems on the fly (in most cases).

Defaulting to Z-axis vertical: The users preferred Axis Orientation

may be set using the Tools-Configure/Setup option, on the

GEOMETRY DIRECTIVES tab. Checking the Z-axis Vertical

checkbox causes CAESAR II to default any new piping, structural

steel, WRC 107, NEMA SM23, API 610, API 617, or API 661

models to use the Z-axis vertical orientation. (Note that old models

will appear in the orientation in which they were last saved.) The

default value in Configure/Setup is unchecked, or Y-axis vertical.

Orienting a piping model to Z-axis vertical: A new piping mode

will determine its axis orientation based on the setting in theConfigure/Setup module, while an existing piping model will use

the same axis orientation under which it was last saved. The axis

orientation may be toggled from Y-Axis to Z-Axis Vertical by

activating the checkbox on the Kaux-Special Execution Parameters

screen, as shown in the figure.

Activating this checkbox causes the model to convert immediately

to match the new axis orientation (i.e., Y-values become Z-values

or vice versa), so there is effectively no change in the model only

in its representation, as shown in the following figures:


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This allows any piping input file to be immediately translated from

one coordinate system into the other.

When including other piping files in a piping model, the axis

orientation of the included files need not match that of the piping

model. Translation occurs immediately upon inclusion.

When including structural files in a piping model, the axis orientationof the included files need not match that of the piping model.

Translation occurs immediately upon inclusion.

The axis orientation of the Static Load Case Builder (i.e., wind and

wave loads), the Static Output Processor, the Dynamic Input Module,

and the Dynamic Output Processor is dictated by the orientation of

the models input file.

Orienting a structural model to Z-axis vertical: A new structural

model will determine its axis orientation based on the setting in the

Configure/Setup module, while an existing structural model will

use the same axis orientation under which it was last saved. The

axis orientation may be toggled from Y-Axis to Z-Axis Vertical bychanging the value of the VERTICAL command, activated by

clicking the button on the toolbar, or through the Commands-

Miscellaneous-VERTICALmenu command, as shown in the figure.

Note: Unlike the piping and equipment files elsewhere

CAESARII, toggling this setting does not translate the structu

input file, but rather physically rotates the model into the n

coordinate system, as shown in the figures below:

(Note to Beta testers: Is it OK to handle the axis orientatconversion differently in the Structural Input Module than how i

handled elsewhere in CAESAR II?)

When including structural files in a piping model, the axis orientati

of the included files need not match that of the piping mod

Translation occurs immediately upon inclusion.

When analyzing a structural model on its own, the axis orientati

of the Static Load Case Builder (i.e., wind and wave loads), t

Static Output Processor, the Dynamic Input Module, and t

Dynamic Output Processor is dictated by the orientation of t

structural models input file.

Orienting an equipment model to Z-axis vertical: The WR

107, NEMA SM23, API 610, API 617, and API 661 equipme

analytical modules may also utilize the Z-axis vertical orientatiA new equipment model will determine its axis orientation based

the setting in the Configure/Setup module, while an existi

equipment model will use the same axis orientation under which

was last saved. The axis orientation may be toggled from Y-Axis

Z-Axis Vertical by activating the checkbox typically found on t

second data input tab of each module, as shown in the followi

figures:


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Activating this checkbox causes the model to convert immediately

to match the new axis orientation (i.e., Y-values become Z-values,

or vice versa), so there is effectively no change in the model only

in the terms of its representation.

When using the Get Loads From Output File button to read in

piping loads from CAESAR II output files, the axis orientation of

the piping files need not match that of the equipment model.Translation occurs immediately during the read-in of the loads.

WORD as an output device:

For those users with access to Microsoft WORD, CAESAR II

provides the ability to send output reports directly to WORD. This

permits the use of all ofWORDs formatting features (font selection,

margin control, etc.) and printer support from the CAESAR II

program. This feature is activated through use of the button (or

some variant) instead of the (display), (print), or (print to

file) buttons when producing a report.

WORD is available as an output device from the following modules

Static Output Processor: Multiple reports may be appended to

form a final report by selecting the desired reports, clicking the

button, closing Word, selecting the next reports to be added, clicking

the button again, etc. A Table of Contents, reflecting the

cumulatively produced reports always appears on the first page of

the WORD document.

Dynamic Output Processor: This processor operates exactly as

does the Static Output Processor: Multiple reports may be appended

to form a final report by selecting the desired reports, clicking the

button, closing WORD, selecting the next reports to be added

clicking the button again, etc. A Table of Contents, reflecting

the cumulatively produced reports always appears on the first page

of the WORD document.

Intersection SIF and Bend SIF Scratchpads, WRC 297, Flange

Analysis, B31G, and Expansion Joint Rating: Clicking the

button performs the calculation and sends the results to WORD.

WRC 107: Clicking the button, rather than the button

performs the initial WRC 107 calculation and sends the results to

WORD. Subsequently, clicking the button performs the Section

VIII, Division 2 summation and appends those results to the WORD

document.

NEMA SM23, API 610, API 617, API 661, HEI, and API 560

Pressing the button performs the calculation and sends the

results to WORD.

Code Compliance report:

Stress checks for multiple static load cases may be included in a

single report using the Code Compliance report, available from the

Static Output processor. For this report, the user selects all load

cases of interest, and then highlights Code Compliance underRepor

Options. The resultant report shows the stress calculation for al

load cases together, on an element-by-element basis.

Load Case Report:

TheLoad Case Reportdocuments the Basic Names (as built in the

Load Case Builder), User-Defined Names, Combination Methods

Load Cycles, and Load Case Options of the static load cases. This

report is available from the General Computed Results column o

the Static Output Processor.


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ODBC/XML Wizard for CAESAR II input and output:

CAESAR II now offers an ODBC Wizard for immediate

interfacing (in addition to the in-line interfacing offered previously)

of both input and output piping model data. (Note that the input

data may only be accessed through the Wizard; while the in-line

interface still transfers only the output data.)

This Wizard, besides being compatible with ODBC (Microsoft

Access and Excel) can also export data in XML format. (Note that

theExcel interface, which was excruciatingly slow under the previous

version ofCAESAR II has been changed to produce a semi-colon

delimited text file, which can be imported into Excel very quickly.)

The interface is accessed via the Tools-External Interfaces-Data

Export Wizardmenu command from the CAESAR II Main Menu.

This brings up the initial Wizard screen; the exported data set can

be developed by simply responding to the questions and clicking

the Next buttons.

The setup procedure defined in the previous newsletter is still

required prior to accessing the new wizard.

Graphics in the WRC 107 Module:

The WRC 107 Analysis module now provides a graphicrepresentation of the nozzle and its imposed loads. This can

accessed via the button on the toolbar.

The displayed load case (SUS, EXP, OCC) can be varied

selecting the tab for that load case immediately before activating t

graphics.

Animated Tutorials:

Under theHelp-Animated Tutorialsmenu of the CAESAR II M

Menu, the user can find a list of a number ofViewlets which u

animation, text, and voice over to demonstrate answers to common

asked questions. (Clicking on the topic runs the tutorial.) The

tutorials, which typically have durations ranging from 30 seconds

5 minutes, cover a variety of topics.


11/28


11

TANK Version 2.20 Released(by: Richard Ay)

In September 2000, TANK Version 2.20 was officially released.

This version ofTANK incorporated Addendum 1 to the 10th Edition

of API-650. Changes in this Addendum include material

modifications and changes to the way corrosion is handled in the

Seismic computations of Appendix E. Since the release of Version

2.20 in September, two updates have been issued and are available

for download from the COADE web site. These updates correct a

data problem in non-US structural steel databases, modify roof

allowable stress checks, and modify live-load reporting for roof

designs.

Anyone using a version ofTANK prior to Version 2.20 should

upgrade immediately. All users of Version 2.20 should ensure they

have the build of 001205 installed.

New Pipe Stress Seminar Format(by: Dave Diehl)

Many of you received our new CAESAR II seminar mailer in late

November or early December. If you havent, you can review its

content on our web site or contact us to mail or fax one to you.

Beyond the 4-color presentation, the most striking component is the

label New Format for 2001. We have expanded the static

analysis section from three days to five days and the dynamic

analysis section from two days to three days. We have four static

sessions and three dynamics session scheduled through 2001.

Reasons for the change

At the conclusion of each seminar we ask all students to evaluate

our course content, instructors and materials. It is the response we

read again and again that indicates people want more time using the

program in group exercises and in individual workshops. Another

common comment is the course pace is too rapid, that there is too

much information to assimilate. We are addressing these issues by

extending the duration of the two segments to allow more time to

develop the topics and work with the software. Another common

suggestion is to provide both an introductory course and an advanced

course. That approach was tried several years ago when we had a

three-day introductory course just ahead of the standard five-daycourse. We were dissatisfied with the result of those arrangements,

as many students who did not attend the introductory course still

required introductory training to the chagrin of the other students.

We have always had to deal with varying levels of student experience.

By slowing down the pace of the course and increasing time on the

computers, we hope to improve the confidence and competence of

all students.

The new static analysis session format

The seminar now has more structure in the day-to-day format. The

first day will introduce the subject of pipe flexibility and stress

analysis focusing on the piping code requirements and generating

proper and effective CAESAR II input. Morning will be lecture

and afternoon will be spent working with the program. Tuesdaywill have the same morning/afternoon split but now the focus is on

properly designing piping systems. We will still focus on design

considerations for each of the basic load categories. Program work

will highlight output review and the redesign cycle; that is, identifying

the significant results and using them to direct system modification

All of Wednesday will be on the computers. We will review and

use many of the added modeling and analysis features of the program

This day will be spent with a job very similar to the tutorial found in

the CAESAR II Applications Guide. Thursday and Friday, the

added static analysis days, will be set aside for group exercises and

workshops. Four different subjects will be coveredtransmission

piping, occasional load evaluation, fiberglass pipe, and jacketed

riser design. We understand that these items are not of universainterest but they are important components of the program and

provide additional insight to the operations of the program, such as

buried pipe, jacketed pipe, and fatigue analysis. Friday afternoon

will be set aside for suggested approaches to documenting and

reproducing an analysis. The week will end with two or three smal

workshop problems to reinforce the learned skills of piping system

modeling, evaluation and redesign.

The new dynamic analysis session format

The three dynamics sessions are scheduled on Monday to Wednesday

of the week following the static analysis sessions. There is no carry-

over from the previous week so students can attend either the staticsor dynamics segment or both, if they wish. The content from the

old, two-day session remains but the pace is reduced and new

material is added. Monday morning covers the required theory and

the afternoon is a harmonic analysis exercise. Tuesday develops

seismic analysis of piping systems and surveys several approaches

to relief valve discharge analysis. This survey was published in the

December 1998 newsletter and provides an intuitive look at the

different types of dynamic analysis. The third day has a group

exercise reviewing time history analysis in CAESAR II and the

afternoon gives us an opportunity to practice what was learned

two or three small workshop problems.

Schedule for 2001

One item that has changed in our seminar brochure is the extent of

our seminar schedule. We normally print a two-year calendar bu

with this new format we thought it best to treat it with some healthy

skepticism and only announce the schedule for 2001. This schedule

appears below:


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12

Statics Dynamics

5-9 Feb. 12-14 Feb.

14-18 May 21-23 May

17-21 Sept. 24-26 Sept.

12-16 Nov. Not offered

COADE also provides in-house training at your site and training

organized by your local CAESAR II dealer. In both cases, a full

eight-day course may not be practical. For in-house applications,

this course can be tailored to focus the content and fit the available

schedule. Dealers will probably maintain the current five-day

course covering statics and dynamics or break the seminar into two

independent courses. Contact your dealer to learn more.

Continuing Education Units

You may be interested in knowing that our courses are monitored

by an outside organization for consistency and effectiveness. In

March 1997 the International Association for Continuing Education

and Training (IACET) certified COADE as an Authorized CEU

Sponsor. The Continuing Education Unit or CEU is a standard

measure of contact hours in training; basically ten contact hours

equal one CEU. IACET is quite rigorous in their criteria for

authorizing CEU sponsors. COADE has adjusted the course content,

presentation, and documentation to meet their standards. This year

we have renewed our application as an IACET Authorized Provider.

We are currently in the renewal cycle of that certification. Among

other uses, these CEUs serve as credit toward the maintenance of a

Professional Engineering license in those states where suchcontinuing education is required. To learn more about IACET you

can visit www.iacet.org. The five-day course will yield 3.5 CEUs

and the three-day course will 2.1 CEUs. If you do the math, thats

seven contact hours a day. In a change from previous courses, we

will start at 9AM rather than 8AM. This will decrease the sessions

from four hours to three-and-a-half hours and ease the intensity of

each session.

Responding to your comments

Once again, it is in response to the evaluations completed by our

students that we have introduced these changes. This new format is

not intended to pull old students back for additional training as the

new content is not segmented into a discreet section. But this

course will provide more complete coverage of those existing topics,

introduce new topics and allocate more time to using the program.

Obviously, one of the major concerns we have with this new course

format is the amount of time we are taking from your regular

schedule. Oftentimes the situation is such that when you really need

the training (a hot project is starting) you dont have the time

attend, and when you have the time to attend (no project; you are

overhead) you dont have the funding. We hope that your compan

commitment to quality work and continuing education will allow

broader outlook on the value of this course.

Sustained Stresses(by: John C. Luf of Washington Industrial Proce

Cleveland, O

Whats A Sustained Stress and why do we care about it?

Due to what may seem to some people, the controversial nature

this articles contents I would like to make it perfectly clear THE

ARE MY OWN OPINIONS! Although, I am sure some may ag

and yet others will disagree with some of the content of this artic

My intent in writing this article is to provide a forum for discussio

give sound advice, and some insight into the subject matter from t

past, present, and possibly the future points of view.

Well where to start? Perhaps we should start with a definition of

word Sustained. From my Random House Dictionary...- Sustain

To keep up or keep going as an action or process.

So how does this apply to the design of piping systems? Stres

caused by thermal displacements of the system are often call

secondary or self limiting. This is because ordinarily the

stresses decrease (slightly) over time. This is illustrated in

figure below, excerpted from one of Markls original papers on t

subject ofFlexibility or Stress Analysis.


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13

You can see that the stress level is not sustained it decreases over

time. As for why, a detailed discussion on this subject can be found

in various publications. Suffice it to say because these stresses are

displacement limited their very nature is self-limited. If the reader

wishes to ponder this a bit more, a simple example would be to, take

an L bend geometry anchored on each end. Imagine it heated or

cooled to the same temperature time and time again. The stresseswill never increase over the maximum from the first heat up so long

as the maximum temperature of the first heat up is never exceeded.

If the strains in the L bends elbow exceed the yield stress of the

metal (as is permissible by the B31 codes) the small area of highest

stress that exceeds the yield strength of the metal in the elbow

yields or deforms. This deformation then redistributes the internal

strain energy to a larger surface and hence the peak stress value

decreases as shown in the hypothetical graph in the figure above.

This cycle of load application, material yielding, and strain

redistribution will occur repeatedly during the first few cycles.

After the strain has been fully redistributed the system will have

been shaken out. This entire phenomenon is often described as a

strain controlled phenomena. After full shakeout occurs allsubsequent cycles will behave in an elastic manner.

Well what types of stresses are sustained? Or better yet what

types of imposed loads on a piping system are sustained and

unrelenting? For an earth bound or planetary-based piping system

everything within that planets field of gravity is constantly loaded

by the gravitational field in a sustained manner. Therefore weight

is a sustained load. Based on the science of Strength of Materials

we know that the bending stress for a simply supported beam has

the maximum stress, located along the bottom of the pipe, at the

midpoint of the span, in the outermost fiber of the pipe.

Mmax at point (C)

M maxw l

2

8:=

and MaxMmax

Z

What other loads are sustained in nature, that act on piping systems?

In general piping systems which become candidates for analysis are

pressurized. This internal pressure loads the pipe walls in tension.

Therefore pressure is generally considered a sustained load (L).

A fair question might be asked, If these loads do not produce

stresses which are self limited what would be the consequences of

an overstressed system? Lets say there is a hypothetical pipingsystem with a span in it that imposes a weight induced bending

stress well above the SMYS (Specified Minimum Yield Strength)

of the metal. Let us also assume during construction the fitter

worried about the saggy, droopy, pipe and add some chainfalls at

the midspans of the longer spans. After hydrotesting is finished the

fitters start cleaning up, they pull the first chainfall out and the next

and so on... The pipe is highly over stressed.... Guess what? When

they take off their chainfalls they also get an extra work order! The

extra work is to replace the pipe, which has collapsed, torn out and

is lying in a pile of twisted metal on the floor below. This is one o

the major concerns of sustained loads; they are also known as

collapsing loads. Other real life examples are buildings, which

suddenly collapse under their weight loads.

I will digress for a moment to talk about the sustained loads of

pressure and weight. Piping systems that are filled and then drained

as a part of their normal operation have that portion of their weight

which is the fluid, acting as a cyclic load. In like manner these types

of systems would have the internal pressure acting as a cyclic load

These cyclic loads are fatigue based loads. Indeed extreme

pressure cycling (unsteady flow pulsation) has been known to cause

failures. However most piping systems do not operate in these

manners (except incidentally), but if a system does operate in this

manner, the issue of sustained versus fatigue type loads should be

considered, however for most systems a few cycles of filling and

draining are of no significance.

Now what does B31.3 say about sustained stresses? 302.3.5 (c

The sum of longitudinal stresses in any component in a piping

system, due to pressure, weight and other sustained loadings shall

not exceed Shin (d) below. The thickness of pipe used in calculating

SL

shall be the nominal thickness T minus mechanical, corrosion

and erosion allowance c, for the location under consideration. The


14/28


14

loads due to weight should be based on the nominal thickness of all

system components unless otherwise justified in a more rigorous

analysis. Axial deadweight loads should be included with bending

in calculating these stresses.

Phew, just think my co-workers and family accuses me of being

long winded! Well let's take the long paragraph (consisting of only3 long sentences) apart one step at a time.

The first sentence combines bending stress due to weight, and

longitudinal stress due to internal pressure. This combination is

based upon the principle of superposition. The stress in the outermost

surface on the bottom of the pipe, (according to simple beam

theory) at the midspan due to a bending moment is a tensile stress.

(Whereas the outermost top of the pipe is under compression.) This

tension stress is combined with the longitudinal stress due to pressure.

These summated stresses are compared against the allowable value

of Sh. This is a more profound thing than people realize. First S

h

stands for the hot stress or... the basic allowable stress at the

maximum elevated temperature expected during the displacementcycle being analyzed. For most materials it is 2/3 of the SMYS

(specified minimum yield strength) of the material.

This is why when CAESAR II detects internal pressure in the input

file it recommends the code load case of W+P. Because this load

case in the program (W+P) contains no thermal displacements some

people refer to this load case as the cold stress load case. This is

wholly incorrect! The Code requires these sustained type stresses

to be reviewed not against the S value of the metal at 70F but rather

at the operating temperature of the metal. The code S value itself

may seem overly conservative (in most cases it is 2/3 of the SMYS

or 1/3 of the tensile strength of the material, whichever is lower at

temperature) but dont forget these loads are sustained loads. Ifthe metal yields due to these applied loads it will continue to yield

until it fails.

The curve above is a typical carbon steel yield curve. As you c

see, once you exceed yield strength the metal continues to stret

under the applied load for a long time. If the redistribution of

load into the yielded metal does not decrease the stress to bel

yield (as the code assumes it does not for sustained loads) the pipi

will fail at the ultimate strength line.

The allowed stress value used is Sh. Why does the code use w

may be a lower allowed S value for metal at a higher temperatu

Well the code seems to presume that once the system heats up it w

also be operating with internal pressure inside the system. In ord

to assure the structural integrity of the piping to these sustain

loads under these circumstances the Sh

is used.

In the remaining code sentences we see some additional interesti

things. The Code uses the approach that it is possible to have

majority of metal in place in a system in a non-corroded state w

the point(s) of highest Sustained stresses being corroded as far

strength is concerned. This approach may be called conservative

some, but it cannot be faulted as being unsafe!

Markl3 (for those who dont know, A.R.C. Markl and his colleagu

were the founding fathers of stress evaluation in the B31 cod

separated the sustained stresses in his original work from the therm

displacement and operating allowable stress range. This approa

guards against incremental collapse due to ratcheting effects.

Sustained Stress Multipliers (Indices):

Sustained Stress Indices (SSI) (or whatever they end up bei

called):

Why the long Code paragraph instead of a simple formula for SAfound under 302.3.5 (1a) i.e., S

A=f (1.25S

c+0.25S

h)? My belief

that some of the reluctance of the committee to provide an equati

for SL

is because of something we have not yet discussed and is n

yet in the Code (ASME B31.3) at the present time.

I hope the readers are all familiar with the term Stress Intensificati

Factor (SIF). These SIFs are used to multiply the beam elem

based calculated thermal (or) other type of displacement stresses

order to approximate the actual level of (higher stresses) that w

occur in the piping component. These SIFs as published in Appen

D of the code are based on physical fatigue tests of actual componen

Once the fitting breaks (a through wall leak develops) a simp

calculation is made as follows:

SM

Z

ia

S Nb( )

a 245000psi

N number_cycles_to_failure

b 0.2


15/28


15

Factors a, and b are material specific, values shown are for carbon

steel.

This calculation is unique from some standpoints. First in lieu of

polished bars, actual welded piping components are tested. Second,

all SIFs are calibrated against a pipe butt weld. The standard pipe

butt weld is assigned an SIF of 1.0.

I have just spent a large amount of effort discussing SIFs, why?

Well as you can see a fatigue test multiplier (SIF) has very little to

do with a Sustained type load. Testing for a sustained type load

might be something on the order of adding weight onto the end of a

fitting in a test setup and seeing how much weight it takes to cause

the fitting to collapse. Then compare that load (perhaps assuming

that it has reached and exceeded the SMYS of the test specimen)

versus a calculated beam element stress. A formula might look like

Sustained Stress Index (SSI) SSI = SMYS/Calculated Stress (based

upon the actual collapsing load) and shall be no less than 1.0.

If we consider this in a thought experiment with some variouscommon piping components we can develop a feel for what an SSI

might be. Consider first an elbow. With a Standard Wt 6NPS LR

elbow we can see where the effect might not be too large. However

conversely a 6x6 NPS standard weight unreinforced intersection

would probably collapse with a much greater difference between it

and a calculated single piece beam element.

Failing all else I suppose we could set up a testing program.

However, to my knowledge such a testing program does not exist.

So to recap the current state as far as SSI factors are concerned...

1) SIFs are not applicable to Sustained collapsing type loads.

2) SSI factors may vary significantly based on the fitting geometry

and may be of greater significance for some fittings than

others.

3) The ASME B31.3 committee does not have a testing program

to derive SSIs currently, although it could be said various

agencies such as the Welding Research Council or the Pressure

Vessel Research Council stand ready to develop these factors

if funding becomes available (corporate donations welcome).

4) The code currently does not address SSIs or have an expression

written for the calculation of SL.

What to do about the SSI?

So whats a poor design stiff supposed to do? I have found over the

years to truly understand the issues of applying code rules to a

design one must be a historian and must be widely read of various

piping codes. When you buy a copy of a B31 code book you buy

the latest version of that code. Unfortunately the many accumulated

years of history of interpretations do not necessarily shine boldly

and visibly in the latest edition. For instance the B31.3 committee

has rendered two opinions on the subject of a SSI. In one

Interpretation (#1-34 (2/23/81)) they said the designer could ignore

the effect of any SSI and use a factor of 1.0. In another separate

interpretation (# 6-03 (12/14/87)) they said the designer could use a

factor of 0.75 x SIF. This seems confusing, but in part it is causedby a lack of information. Maybe if we look elsewhere we can gain

some help?

Turning to ASME B31.1 we find some interesting things on this

subject matter. We find first of all an expression for SL! Also we

find the calculated SL

stresses being multiplied by a factor of

0.75SIF. So if we base our engineering on nothing other than

populism it seems like we should use a SSI = 0.75 SIF 1.0, at leas

for right now1. So for the time being I would recommend that thi

factor of 0.75 SIF 1.0 = SSI be used in analysis. This can easily be

set in the CAESAR II configuration setup.

Set up of the configuration file (file name CAESAR.CFG) is readilyaccomplished through the Main menu as follows

1. From the main menu window select the configure set up icon

2. Next select the SIFs and Stresses tab.


16/28


16

3. Select the 0.75 option from the drop down box and dont

forget to exit with save.

If for no other purpose this factor can act as a screening tool. For

instance I would be less concerned over a slightly over stressed tee/

intersection using 0.75 SIF as the SSI than an elbow1. In case of

doubt, though, a more rigorous review using alternate methods

should be made (When in doubt make it stout, or refine your

calculations).

Non - Linear Pipe Supports (+ys):

Personal Computers are the constant companions of design engineers

today. The advent of this ubiquitous technology is both a blessingand a curse. Currently in our world of compressed schedules and

segmented work efforts, pipe supports, their locations and types,

are often selected by a designer on the basis of span charts. The

Stress Analyst / Piping Engineer then accounts for thermal

displacements (as well as their impact) after the fact.

This approach while it may be more efficient (a maybe at best) can

cause significant difficulties to occur as far as sustained stresses in

the piping system are concerned. What am I talking about? When

displaced by thermal effects the system may completely or partially

lift off certain non-linear pipe supports.

What types of supports are non-linear? Pipe racks, trapezes, clevishangers, or any other support which supports the pipe fully only in

one direction. These types of supports are unable to provide the

same supporting force at the displaced position versus the non-

displaced position. I should also point out a legitimate use of a +y

support that is lifted off is a maintenance or turn around support.

These supports allow maintenance of flanged connections by

providing support for one or more sides of a flange which is un-

bolted during maintenance shut downs.

Pump

Hot Oil @ 600 F

Carbon Steel A53 Gr BPipeCarbon Steel Fittngs,Valves, and Pump

Load OnSupport Beam

Time

Temperature

Side Elevation of HypotheticalPump Support

2'-9"

Max Ld

No Ld

MaxOpTemp

AmbTemp

12'-0"

In the example above the load on the support beam carrying the pi

and some of the valve weight quickly decreases as the system com

up in temperature until finally it is lifted off and drops to zero lo

before the system gets to its maximum temperature! (Guess w

happens to the pump loading? I suppose thats what spring cans

used for!)

The result of this type of support lift off is that if one evaluates

system for SL

stresses in only one state you may not be seeing t

complete picture. The code requires evaluations for SL

at vario

temperatures. Some people call these evaluations as cold sustain

and hot sustained stress checks.

The following example illustrates the problems associate with supp

lift off. I have been permitted to borrow it from its current auth

Mr. Don Edwards of ASME B31.3 task group B. The task gro

has been working on a non mandatoryAppendix S whose purpo

will be to illustrate the code and its relationship to computeriz

analysis. Note in no way, shape, or form is this supposed

represent good practice! It is only a hypothetical layout!

10'-0"

40'-0"

10'-0"

20'-0"

Typ.

Stated Data:

Material-Carbon Steel A106Grb, AstmA234 Gr WPBNPS-16Wall-Standard Wt (0.375" Nom Wall)Elbows LRInsulation-3" Thk Density = 11.0 #/Ft3Corrosion Allowance = 1/16"Fluid Density=1.0 S.G.Maximum Op. Pressure = 500 P.S.I.G.Maximum Op. Temperature = 600 FMinimum Operating Temp = 70FInstallation Temp = 70 F

Fix Y

+Y

Anchor6 D.O.F.

Proposed Appendix S Model

1020

45 55

8040'-0"

Typ.

10'-0"

Typ.

90

Y

X

Z

+Y


17/28


17

When the loop heats up, it will lift off the upper supports. The first

pass SL

code stress calculation is made with the upper supports

active i.e., supporting the pipe. This is required to obtain the

thermal displacements from the installed position to the displaced

position. When SL

is evaluated with the pipe sitting on these

supports SL

stresses are within the code allowable.

However when we look at the CAESAR II Restraint Summation

(in the 132 column format) at nodes 45 and 55 we see the loads go

to zero in the operating case and a look over at the displacements

shows a +y movement.

The liftoffs effects should be re-evaluated by performing another

SL

analysis with the supports at nodes 45 and 55 removed from the

model. When this is done it turns out the code SL

stress limit is

exceeded (this evaluation is made using a SSI = 0.75 SIF 1.0).

This second analysis determines the sustained stress (B31.3 Code

stress) redistribution, it is not used for any other purpose (i.e. code

stress review of displacement stresses). Leave the thermal data in

the job so that the proper Sh

is used. To sum up, the supports at

nodes 45 and 55 are used for evaluating the thermal displacements,

but are removed to evaluate the code sustained stress level. (It

should be noted that restraint summaries shown herein show the

pure thermal forces to illustrate the book keeping on the restraints.

These thermal loads would not be used for support design).

When this sample problem was discussed at the committee's last

meeting a visitor asked, Well what should be done? Some of the

committee members stated that first, an evaluation with the lifted

off supports removed from the model should be made and then

finally some members saidThat redesign of the system should

be made to eliminate the over stressed condition. Clearly some of

the committee members opinions do not agree with ignoring lift

off. The visitor then mentioned, You should put a spring can(s) onthe top of the loop! I myself countered that spring cans might not

be necessary! I disagreed strongly and suggested that jiggling

support locations around would probably solve the overload. Indeed

moving the supports at 20 and 80 inwards a couple of feet (towards

the loop) make the overstressed condition go away (Although the

midpoint sag would probably be unacceptable by most criterias for

drainage). Sometimes spring cans are good things (especially

adjacent to rotating and other sensitive/delicate equipment), and

other times adding a fixed pipe support(+y) or moving supports

around will easily solve a SL

overstress. In any event it is unlikely

that if or when Appendix S is published that the sample problems

will show a preferred solution. This is because the committee's role

is to tell the users to do their homework, give advice on how to do

the homework, but the committee will never do the users' homework

for them.

Judicious use of Engineering Judgement:

It is the authors opinion that engineering judgement can and

should play a role in the process of sustained stress evaluations

Turning to another example:

5'-0" 5'-0" 5'-0"

3'-0"

8'-0"

3'-0"

5'-0" 5'-0"

10 20 30

40 50

60

70 80

90

Design Data:Code: ASME B31.3Pipe: A53Gr B SmlssWall : Standard Wt.NPS: 6Elbows: L.R. 90Degree B.E.

Process Data:Maximum operating temperature :180FMinimum operating temperature: 70 FInstallation temperature : 70 FMaximum operating pressure 250PSIG

Y

X

Z

We have another hypothetical layout; this contrived geometry is

for illustration only. Other than the close support spacing in thi

example I have seen lines run in racks supported in similar fashion

on either side of the riser elbow pair.

If we look at a deflected plot of the operating case we see that the

pipe has clearly lifted off and when we take a look at the restraint

summation we see this as well.


18/28


18

Load shift to

0, sticks out!

Small +

movement

Looking closely we see the liftoff(s) in the operating case are by

extremely small amounts. So what would be the appropriate way todeal with this design?

Well the first step has already been taken. That is a review of the

restraint summation. This essential step I suspect is often ignored!

I have heard people occasionally say that CAESAR II does not

evaluate support lift off correctly. However, I feel that a piping

engineer reviewing, and supervising the non-sentient computer is

essential to the work process. The review process and the ability of

who does the review is very important. When the lift off

displacement is equal to or less than the fabrication tolerance of the

piping, the designers gray matter is much more important than the

computers chip speed (D. Edwards).

One method of evaluation could be by feel, which is, it is readily

apparent that the bending stress portion of SLis minuscule. Therefore

the liftoff adjacent to the elbow becomes of no concern. However I

suppose there are those persons who are trying to develop feel. In

that case I suggest another way that you could look at this would be

to use a span chart such as found in MSS SP 69 2. Looking at its

span limits for 6NPS Std. Wt. Steel pipe that is used in water service

we see that we could have spans seventeen feet (17) in length. The

distance from node 40 to node 80 is only eleven feet (11 ) well

within the span chart limit. What about the effect of the SSI on the

elbows calculated code stresses? Well it feels like it should be low,

but in order to evaluate it numerically we will have to remove the

support lifted off at node 70, copy the file into a new name, and

reanalyze it using the SSI = 0.75 SIF 1.0 CAESAR II

Configuration option. When we do this and examine a stress report

we see all is well.

It should be noted that if one were to calculate the SIF for the

elbows per the Code you would get the number shown in the repo

CAESAR II will use a numerically adjusted value per t

configuration setup as a multiplier despite the fact that the code S

is shown on the report. Why not adjust the value shown on

report? Well the column heading says SIF, not SSI therefore

essence because the codes have not adopted the use of a SSI wh

do you call the ad hoc SSI in code terminology?

At this point I would suggest that we have met the intent of ASM

B31.3. We have evaluated the SL

stresses in two states and ha

complied with the code stress limit in both cases. I would suggnotations be placed on the restraint summation report at the lift

off nodes, such as Support liftoff is incidental, spans as lifted

comply with ASME B31.3 SL

limits

So a summation of one mans opinions:

9 Adult supervision of the computer is always required. W

I mean by this statement is, that I consider the computer to

like a young child who requires adult or parental supervis

at all times.

9 Use the CAESAR II, 0.75SIF option in the configurati

setup as a multiplier for the SL case. Its probably not 100right but it is more appropriate than 1.0. Besides whi

usually a maximum deflection criterion dominates the pi

support layout and design. (Editor's Note: CAESAR

defaults to use of the full SIF, not 1.0 as the SSI.)

9 Review the 132 column restraint summary reports looking

load shifts or lift off at non-linear +Y supports. Pay clo

attention to supports adjacent to rotating equipment.


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9 Evaluate the amount, type and locations of lift offs. If lift off

versus the system's design is minor or incidental write your

comments on the archival report.

9 If the lift offs are more than minor, such that their effects on

the code SL

cannot be readily discerned, remove the supports

(+ys) that are lifted off from the model. Rerun the sustained

stress case.

9 If redesign is required, modify the support scheme by support

relocation, or adding +y supports, or spring cans with the

thought in mind that spring cans (except when adjacent to

sensitive equipment nozzles) are usually less desirable.

References (additional reading):

1) Pressure Vessel and Piping Codes Journal of Pressure

Vessel Technology August 1988 Commentary on Class 2/3

Piping Rules Authors comment this provides some of the

technical background behind the use of the factor of 0.75 as a

SIF multiplier.

2) Manufacturers Standardization Society of the Valve and

Fitting Industry, Inc. Standard Practice SP69 "Pipe Hangers

and Supports Selection and Application".

3) Transactions of the ASME, February 1955,Piping Flexibility

Analysis

A huge thanks to my editors

Rich Ay, COADE

Dave Diehl, COADE

Don Edwards, Phillips Petroleum

Phil Ellenberger, WFI

Late Breaking News

Over a year ago COADE started the process to register its name

and all product names as trademarks with the U.S. Patent and

Trademark Office. We are pleased to report that both

CAESAR II and PVElite are now registered to COADE. Other

names should be registered soon.

Vessel seminar dates are announced. Our three day vessel

seminar using CodeCalc and PVElite is scheduled for 21-23

February and 10-12 October 2001. The first two days cover

component analysis (found in CodeCalc and PVElite) and theoptional third day continues with a whole vessel approach to

design in PVElite. Ask for a brochure or view a copy on our web

site for more information.

Please register as a user of our software. Registered users receive

a brief e-mail identifying new program releases and Builds as

they become available. This heads up will keep you up to date

with the current software and eliminate your need to monitor our

web site for new postings.

Utilizing the New Load Case Editor

in CAESAR II Version 4.30(by: Richard Ay

For Version 4.30, the Load Case Editor in CAESAR II experienced

significant revisions. These modifications simplify the specificationof load cases, streamline the output data, and allow additiona

analysis capabilities. The revised load case editor dialog is shown

in the figure below. In this figure, areas that have been changed are

indicated with numerals, and are explained in the following

paragraphs.

Item 1: In previous versions of the software, the available stress

types were listed on the lower left side of the dialog. (The stress

type determines what stress equations are used in the solution

module.) Users could either drag the stress type onto a load case

or manually type in the abbreviation. As of Version 4.30, the

stress type for each load case is selected from a drop list

Simply clicking on the stress type grid cell activates this drop

list.

Item 2: In previous versions of the software, algebraic load case

combinations could be combined at various levels; displacement

force, or stress. This was indicated on the right side of the dialog

where DS indicated the displacement level, FR indicated the force

level, and ST indicated the stress level. As of Version 4.30, thi

combination level idea is obsolete, and has been replaced by an

output type indicator. The type of output desired for a particula

load case can be specified on the Load Case Options tab, whose

dialog is shown in the figure below.

Item 3: The Load Case Options tab is new for Version 4.30

Clicking on this tab presents additional load case controls. These

new controls are shown in the figure below.


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Item 4: Any load case component can be preceded by a numeric

multiplier. This means that safety factors can be applied at the load

case level, instead of in the input.

Load Case Name: This grid column can be used to define a name

for a particular load case. For example, instead of wondering what

W+T1+P1+D1+F1 might represent, you can now type in a name

such as Operating + Cold Spring. Both the formal load case

component definition and the load case name can be used at the

output level for review and report generation.

Output Status: This grid column is used to specify whether or not

a particular load case will have output available for review. The

Discard setting allows intermediate and construction load cases

to be ignored by the output processor, which simplifies outputreview and evaluation.

Output Type: For load cases where the Output Status is set to

Keep, this grid column specifies exactly what type of output will

be available. So for a typical operating case, this setting should

indicateDisplacement/Force, while a typical expansion case should

indicate only Stress. With these settings, stresses would be

unavailable for the operating case, while displacements, forces, and

restraint loads would be unavailable for the expansion case.

Combination Method: Previous versions ofCAESAR II used an

algebraic combination method when combining load cases at

either the displacement or force level, and an absolute or scalarcombination method when combining load cases at the stress level.

{The use of an algebraic combination is required by the B31

codes (for instance see ASME B31.3 Paragraph 319.2.3) for review

of displacement stresses. In the review of B31 piping systems the

user is strongly encouraged to continue the use of the algebraic

summation method for the review of displacement stresses.}

As discussed above, this level idea is now obsolete, bei

superceded by the output status and output type settin

However, there are instances where it is necessary to control t

combination method used, as well as other methods in addition

algebraic and scalar. The additional combination methods

absolute, SRSS (square root sum of squares), Min, Ma

Signed Min, and Signed Max, have been added for Versi4.30.

Complete documentation on the correct usage of these options c

be found in the CAESAR II documentation, as well as the on-l

help. However, an example will be used to illustrate the usage

these new capabilities.

Assume we must statically analyze a model (with only line

boundary conditions) for a seismic event. (A plot of this symmetr

simple model is shown below.) For this seismic event, G load

have been specified for each global direction, X, Y, and Z. The

loads have been defined as U1, U2, and U3 respectively, as show

in the figure below.

To properly address the code requirements for occasional stre

checks, and to evaluate the restraint loads on the system, the followi

set of load cases have been defined.

Case Components Stress Type Comments

1 W+P1+T1 OPE Operating

2 W+P1 SUS Sustained

3 U1 OCC Seismic load X

4 U2 OCC Seismic load Y

5 U3 OCC Seismic load Z

6 L1-L2 EXP Expansion range code case

7 L3+L4+L5 OCC Resultant seismic load, SRSS combination

8 L1+L7 OCC Operating plus seismic combined absolutehot restraint loads

9 L2+L7 OCC Sustained plus seismic combined absolutecold restraint loads, code case

10 L9, L8 OCC Maximum restraint loads

With the new load case editor, these load cases can be defin

exactly as laid out in the table above. This load case layout

defined on two related dialogs, as shown in the figures below.


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The figure above is the familiar load case editor screen. Note

however that the load case stress type is now selected from a droplist for each specific load case. This drop list is shown activated

for the last load case in the figure above. The above screen is

essentially the same as in previous versions ofCAESAR II. The

two obvious differences are the stress type drop list and the setup

of the combination load cases. Consider for example load case 6

above. Previous versions ofCAESAR II would have listed case 6

as DS1 - DS2. As of Version 4.30, this same load case is listed as

L1 - L2. The combination methods and the output type (formerly

combination level) are defined on the second load case definition

dialog, shown in the figure below.

The second dialog shows the advanced load case controls offered

by Version 4.30. First, note that the load cases can be given

meaningful names - these names are user defined. Second, the

Output Status column provides two settings for each load case

keep and discard. In this context, keep means that the data

from the load case will be available for review in the output processor

while discard means that the data from the load case will not beavailable for review. The discard setting would typically be

applied to construction load cases, those cases used solely to

build other cases.

The Output Type column indicates what type of data will be

available for review in the output processor (assuming the Outpu

Status is set to keep). Setting a load case to Disp/Force/Stress

means that displacements, forces (and restraint loads), and stresses

will be available at the output level for review. Setting a load case

to Disp/Force means that only displacements and forces (and

restraint loads) will be available at the output level for review. This

is the preferred setting for typical B31.1/B31.3 operating cases

(OPE), where the stress results are not code related and are ofminimal use. Conversely, setting a load case to Stress means tha

only stresses will be available at the output level for review. This is

the preferred setting for typical B31.1/B31.3 expansion cases, where

only the stress range is needed. The displacements and forces fo

this case are also ranges and are typically of minimal use.

The final column on this dialog Comb Method defines for each

combination load case, the combination method to be employed. In

versions of CAESAR II prior to 4.30, combination load cases

combined at the displacement or force level were combined

algebraically. Load cases combined at the stress level were combined

in a scalar fashion. As of Version 4.30, the user has control over the

combination methods. Additionally, the combination methods havebeen expanded to also include Absolute, SRSS, Min, Max, signed

Min, and signed Max.

The best way to understand the new capabilities of the static load

case editor is through the use of the example started above

Examining the load cases in more detail shows:

Load cases 3, 4, and 5 are comprised of only a single seismic

load (direction). By themselves, these load cases provide

minimal information, they exist solely as construction cases

Load case 6 is the standard expansion load case, which

determines the extreme displacement stress range bysubtracting case 2 from case 1. In previous versions o

CAESAR II, this load case would have been denoted as DS1

- DS2.

Load case 7 is a combination case, constructed by computing

the square root sum of squares of load cases 3, 4, and 5. (Prio

versions ofCAESAR IIcould not perform this computation.

This load case yields the combined effect of the three seismic

loads.


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Load case 8 is a combination case, constructed by adding the

operating case to the combined seismic case. This combination

is made taking the absolute values from each of the component

load cases. (Prior versions ofCAESAR II could not perform

this computation.) This load case yields the absolute value of

hot restraint loads.

Load case 9 is a combination case, constructed by adding the

sustained case to the combined seismic case. This combination

is made taking the absolute values from each of the component

load cases. (Prior versions ofCAESAR II could not perform

this computation.) This load case yields the cold restraint

loads. This case is also the code compliance case satisfying

the requirements thesustained plus occasionalcode equation.

Prior versions of CAESAR II performed this code computation

at the stress level, i.e., ST2 + ST7.

Load cases 10 is a combination case, constructed by taking the

maximum results from cases 8 and 9. The absolute magnitude

of the values from each case are used in determining themaxima. (Prior versions ofCAESAR II could not perform

this computation.) This load case yields the maximum

restraint loads.

For this particular job, a review of the restraint summary for load

cases 3, 4, 5, and 7 shows expected results for this symmetric

model, as illustrated in the figure below.

Similarly, a restraint summary comprised of load cases 1, 2, and 7

yields expected results in cases 8 and 9, as illustrated in the figure

below.

And finally, a restraint summary comprised of case 8, 9, and

shows the maximum restraint loads as expected, illustrated in t

figure below.

In a production environment, with a real job, we can take mo

advantage of these new load case capabilities. In this sim

example, the results of load cases 3, 4, 5, and 7 are of minim


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interest - these are just construction load cases. Additionally, we

dont care what the stresses in the Operating case are, nor do we

care what the displacements and forces are in the Expansion case.

We can make these eliminations on the Load Case Options tab of

the static Load Case Editor. The figure below shows this dialog

after these changes have been made.

Upon running the analysis with this load case setup, the resulting

output menu is modified, as shown in the figure below.

Here we see that the load cases set to discard in the Load Case

Editor are labeled Not Active at the output level. We cannot

review data for these load cases. This greatly simplifies reporting,

and the need to explain why stresses for these cases are of no

importance. Another option that makes interpreting the results

easier is the user specified load case names. These user defined

names can be shown in the output by selecting the Load Case

Names option from the Options menu, or by clicking on the load

Documents

Good Book Load Case Editor