Dynamic Analysis FAQ:

• Modal

• Response Spectrum

• Harmonic

• Time History

• Force Spectrum

General Comments, Questions, and Answers

Item #1:

There is some confusion on how AutoPIPE closes the gap of a support in a dynamic analysis.  It isn’t clear how this makes sense that the program will apply a support at a point where the pipe may not actually be moving enough lose the gap and to reach the support in reality.  Anyclarification on this?

Answer: All AutoPIPE Dynamic analysis require that a modal analysis be performed. From AutoPIPE online help:

AutoPIPE lumps the mass of the pipe, components and contents, etc. at the associated node point. This assumption yields a diagonal mass matrix with no mass coupling terms. There are three mass degrees of freedom per node. Rotational mass is ignored, except for points with eccentric weights, specified using the Insert/Xtra data/Weight command). At these points there may be up to three additional rotational masses and thus three additional mass degrees of freedom.

It should be noted that for the eccentric weight, the coupling terms between the translational and rotational degrees of freedom are neglected. The structure is assumed to be linear and thus all gaps, friction and soil yielding is ignored.

Item #2:

Program should block dynamic analysis if static analysis set #1 not analyzed.

Answer: This has been logged as a new enhancement under CAE-CR-10998. The internal setup of all the dynamic cases still rests with analysis set #1. If analysis set #1 is not analyzed with dynamic loads specified, your dynamic cases cannot be setup properly.

Item #3

For V-Stop type support, like rod hanger, is AutoPIPE capable of deactivating the support in dynamic analysis in the analysis when it is active in static analysis?

Answer: No, supports cannot be diactivated for a dynamic analysis. Only work around is to create a model with the support actually removed for dynamic analysis.

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Comments, Questions, and Answers about No-code combinations in AutoPIPE

Item #1:

How to set up a non-code combination to print 0.3*gravity when axial displacement at a support exceeds 1/8" in thermal load case?

Answer: We apologize for the inconvenience, but there is no mechanism to have a combination set up based on a value result in another combination.

You can filter the output report based on values (see Results> Filter Criteria) , but you would still need to manually create the combination that can be enabled to be printed or not (see Tools> Combination> non-code tab> print option). 

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Load Combinations 

To review, modify or print new post processing combinations defined for the current model, select Tools> Combinations. The exact list of combinations will depend on the active load cases analyzed and the code
associated with the current system.

There are four distinct TAB GRIDS appearing on the Combination dialog:

1. Load Cases - All the analyzed static and dynamic load cases are displayed for each analysis set in the grid.

2. Code Comb. - The "Code Compliance" grid displays the combination set defined for piping code compliance.

3. Non-Code Comb. - The "Non-Code" grid displays the active load case combination set defined for any purpose other than code compliance

4. User Allowable - The "User Allowable" grid displays the allowable stresses to be used in the pre-verification and stress summary reports (ASME NB, NC, and ND codes only). 

NOTE: Press the help button on tthe Tools> Combinations dialog to see on line help details for each of the available features.

User load combinations

Once an analysis has been run, use Tools> Combinations to see all code and non-code combinations. AutoPIPE automatically combines the loads required to calculate piping code stresses. The "Other" category contains loads, which need to be combined by the user in order to analyze piping loads on equipment, piping loads on supports, and deflections under various applied loading conditions.

In order to evaluate cold (ambient) load and operating loads on supports and equipment, users may combine individual loads by using creating User-defined Combinations on the respective Code/Non-code comb. tab. For the combination name, choose something meaningful such as GR+T1, GR+T1+W1, etc. Typically, combinations for support and equipment loads are made using the Sum or Absolute Sum combination methods, although users may also use the SRSS combination or Resultant maximum methods to combine loads. On the same screen, select the loads to be combined to make up your operating loads (see Figures below).

 AutoPIPE 6.0 - 8.6

AutoPIPE V8i 9.0 and higher:

Non-Code Combinations Dialog

Code Combinations Dialog

After defining all your operating load combinations (GR+T1, GR+T1+W1, GR+T1+W2, etc.), it may be a good idea to create 2 more combinations for your MIN and MAX to more easily review support loads. Typically, engineers will use the MIN and MAX for their GR and all operating load combinations, ignoring the individual loads for Tl, Wl, W2, El, E2, etc. The MIN and MAX sort through all the selected loads and load combinations, and produce Minimum and Maximum results. The MIN and MAX results for support loads and deflections are a great tool for creating summary reports for the civil/structural engineer responsible for piping support design, saving significant man-hours in the review of worst case loads on supports and equipment.

For reporting purposes, users can minimize output by selecting

AutoPIPE 6.0 - 8.6: Tools> Non-code Combinations> 

AutoPIPE 9.0 and higher: Tools> Combinations> choose Code/Non-code Tab and press New Button.. 

select and de-selecting individual loads or combinations which do not need to be reported. After saving these combinations, the *.CMB file can be copied and renamed to another job, eliminating the need to create user combinations each time.

Please note that users can input a "-1" in the load factor field to analyze wind and seismic loads in the negative direction, e.g. GR+T1-WI, GR+T1-W2. This "-1" feature can be used if gaps or friction do not significantly affect piping loads at a particular support point or equipment connection. This negative direction can be included as part of your user load combinations, enabling users to evaluate results using operating load combinations with wind and seismic analyzed in both the negative and positive directions. AutoPIPE does consider gaps and friction only for the load directions chosen for the original analysis.

Questions and Answers:

• "Code Comb" tab Questions:

• "Non-Code Comb." tab questions

• General questions not covered by above WIKI pages

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Problem:

What are some typical modeling approaches for different types of piping?

Answer:

 #1: Coated PIPE (ex. concrete encased steel pipe):

There is no accurate way to simulate this analysis. In order to correctly account for the pipe & concrete stiffness, you would need outside program values for total pipe stiffness (pipe & coating), 

OR, suggest to calculate an equivalent steel thickness by calculating the equivalent moment of inertia.

Es*Ie = Es*Is + Ec*Ic

Where Es, Ec stand for modulus of elasticity of steel and concrete respectively.

Ie, Is and Ic are the equivalent moment of inertia, steel pipe inertia and concrete pipe coating inertia. The inertia can be approximated by

Pi * R^3 * t

R is the mean radius of the pipe or coating.

Assume equivalent radius is same as steel radius and solve for equivalent thickness. You can recompute equivalent radius and solve again for new thickness.

Please note you may use 1/2 or so (cannot recall exact number as neutral axis will move) of the concrete inertia as it will crack in tension. AutoPipe will give you stress in the equivalent steel pipe. You may need to evaluate the stress at most stress point by splitting the moment between pipe
and coating proportional to their E*I.

For example Ms = M * EsIs/EsIe and Mc = M* EcIc/EsIe

And calculate stress for pipe and concrete using their actual diameter,thickness and material.

So in conclusion, of modeling a concrete encased steel pipe, based on the information above:

1. Insert a pipe property

2. Combined Concrete / Steel Stiffness:
      a. Set Pipe material = Ns (nonstandard)
      b. Calculate / insert the pipe properties for the combined Concrete / Steel Pipe

3. Account for weight and correct size:
      a. Set insulation thickness = XXX inches
      b. Set Insulation material = Other
      c. Set Insulation density = XXX lbs/cuft ( for concrete only).
      d. Set Density = XXX lbs/cuft ( for steel only)

Note: setting the correct insulation thickness, insulation density, and pipe density will accurately account for the weight and outside dia of the combined pipe/ concrete for the wind / wave / current loading.

4. Because the material is set to NS, update the data on the Press / Temp/ PipeID tab.

      a. Calculate and insert the expansion coeff, hot mod, and hot allowable based on the combined
           concrete / steel pipe.

Notes:

Take care not to double up on insulation/lining density and pipe density

#2. Corroded PIpe or Spot corrosion?:

Question: Does AutoPIPE offer a function or upgrade that will analyze corroded pipe with the following user informaiton:

a. Corrosion network sizes
b. Longitudinal and rotational positions
c. Minimum wall thickness at pit depths

Answer:
The following enhancment has been logged: CAE-CR-10121, Add ASME B31G: Remaining Strength of Corroded pipeline. 

#3. Corrugated Straight pipe

There are 3 options to choose from:

A. Apply a special pipe id to the legth of corrugated piping changeing that pipe id's Pipe material to NS (NonStandard), update pipe properties using equivalent stiffness values in Long Modulus, Hoop Modulus, and shear Modulus; adjusting other pipe properties as needed.

B. Place back to back Flexible joints over the length of straight pipe using the correct stiffness values.

C. Insert back to back bends over the length of straight pipe, for example 10/1000 angle at each bend, but ending with straight end connections. In the model input grid change the bend's Flexibility Factor from Automatic to the correct value.
        Note: there has been no official testing done using option C, but appears to work in theory

 #4 Jacketed Piping

Please see the following AutoPIPE help section:
Help > Contents> Contents Tab> Modeling Approaches> Modeling Approaches> Pipes> Jacketed Pipe

First create the carrier pipe with locations of all spider supports along the inside of the jacket piping. Then easily create the Jacket by using the graphical Select and Copy / Paste functions. Select the range of carrier pipe including valves, flanges, reducers etc and paste the coped selection with a small offset (remember - no 2 node points should be in the exact same point, small offset). This modeling technique is covered in advanced training.

Notes:

a. Carrier pipe and jacket modeled as two separate segments with different pipe identifiers e.g. Jacket6 and carrier8

b. Segments may be made of different materials and have different operating conditions

c. Carrier pipe is supported by the jacket at regular intervals using spacers (spider support) and at flanged ends.

d. Spacers are modeled as two point supports e.g. guide between acarrier segment point and a jacket segment point.

e. If both carrier and jacket are liquid filled wiht the same liquid then adjust jacket SG accordingly, while settng the carrier piping SG = 0.000 over the length of jacket piping. The model would bo double counting weight of contents if both pipes SG were entered.

f. Remember to only apply hydrodynamic (e.g. submerged piping), wind, and insulation only to jacket.

g. Ideally suited for graphical copy/paste operations

h. New segment cannot be inserted at the start of a 2 point componentlike a valve. New segment at end of the valve is ok therefore need to insert small run point before the valve to connect the jacket segment.

i. Be sure to check any interference between inner and outter jacket. AutoPIPE does not perform clash detection. Recommend export model to Bentley Navigator.

j. Consider taking an offical AutoPIPE training class, this is covered in the class with extra documentation.

i. For underground jacketed pipe, apply soil properties to the Jacket (outside) pipe only, the carrier pipe insde of the jacket is supported by spacers, not soil. Agian, confirm soil properties are only applied to the outside pipe for the length of jacketed piping underground.  

k. Recommend setting pipe graphics to be transparent, View> Transparency> toggle the check box ON for Pipe, and press OK button. View model is solid model view, similar to screen shot above.

L. Model multiple carrier pipes using the same technique as shown above, connecting all carrier pipe supports to the same node point on the jacketd pipe.  

 

#5 Large Bore Piping:

Question: Are there any problems analyzing big diameter pipe systems? It was indicated that some issues with regards to Caesar's analysis of big diameter pipe analysis?

Answer: This is a long standing issue with the Piping codes and this question comes up often. Basically the piping codes only supports SIF calculations for D/t < 100, hence large diameter pipes fall outside this limit.  Caesar prints a warning when this occurs and AutoPIPE will be doing the same in v9.1. We recommend for users to perform a local stress analysis at these connections and/or determine a SIF from e.g. FEA and add back into the program

#6. Can AutoPipe handle 12 to 30 foot diameter welded steel pipes with internal veins? Mostly for steam flow…

Answer: Yes, AutoPIPE can be trusted to model large diameter piping systems as long as it does not exceed the code requirements. However, when D/T > 100, AutoPIPE can be used to provide the correct forces, moments, and displacements in the piping system by applying these user-defined SIF and flexibility factors. Care should be taken with such systems as they are susceptible to ovaling and denting and that should be considered while lifting or supporting the pipes.

Modeling, an equivalent pipe section with same section modulus for this large pipe with stiffeners could be calculated. Then adjust the density of pipe to get the equivalent weight of stiffened pipe when selecting a non-standard material (NS).

#7. Rigid Pipe Element with "ZERO" Mass (Pipe & Water S.G.=0)

Answer: Select a range of pipe, press Insert> Rigid options over Range> uncheck "Include Weight" and user choice to consider "Include Thermal Expansion". 

#8. Pipe Lining:

Question: what is the best way to model material on the ID of pipes. 

Answer: The cladding mentioned in the pipe properties grid is referring to application on the outer most diameter of insulation. 

On the pipe properties dialog, enter as lining thickness. Please note that lining is an added weight only and would not contribute the pipe stiffness. If this lining increases the stiffness, then a modified pipe modulus may be entered by computing an equivalent modulus that would give that same EI
 
Ee*Is=Es*Is+Ec*Ic
 
This will give correct bending stifness by using Ee instead of Es in AutoPIPE. Axial stifness will be approximate. s=steel, c=CRA. Is=steel moment of inertia.

#9. How to model NFPA pipe? Does AutoPipe have Fire Protection Requirement capabilities?

Answer: NFPA (National Fire Protection Association) codes provide specific details about design, construction, operation, and maintenance of piping systems for fire protection.

To answer these questions, at this point AutoPIPE does not have a specific NFPA piping code. However, NFPA codes typically refers to the appropriate ASME design code which AutoPIPE may already have. Please review your NFPA code for stress analysis requirements. If AutoPIPE was found to contain the correct Piping Code specifed by NFPA, then model the piping system in AutoPIPE as required.

#10. Can you analyze tubing, i.e. small dia [ex. 1/2" (13mm)]? 

Answer: Yes, AutoPIPE has been used in devlopment of tubing systems by our many uers.

From the AutoPIPE online help:

Standard Pipe Cross Sections - ANSI/ASME Library. This library of pipe cross sections pertains to the ANSI/ASME codes B36.10M and B36.19M (1985).  They are contained in the file AUTOPIPE.LIB. Pipe sizes from 1/8 (.405") OD with 0.049" wall thk, up to 36" sch 40 wall thk.

Copper Tubing Type L (ASTM B88 Refrigeration piping), pipe sizes from 1/4 (.375") OD with 0.030" wall thk up to 3" (3.125") OD with 0.090" wall thk

#11. My pipe size and material is not available in AutoPIPE libraries. What options do I have?

Answer:

A. Pipe size options:

AutoPIPE can model almost any size pipe used in most tyical piping system built today. for a complete list of pipe sizes available in AutoPIPE, please see the following AutoPIPE help section:
Help > Contents> Contents Tab> Reference Information> Libraries>  Standard Pipe Cross Sections

1. If you need to specify a pipe that is not currently in the library, perform the following: open the pipe properties dilog screen in a model, place cursor in the "Nominal Diameter" field and press F1 keyboard key. This will display the help for this field, there are instructions on how to enter in your Non-Standard (NS) pipe size.

 2. If you like the pipe size added to a customize library file, please log a service ticket requesting information about creating a Component Library file.

B. Pipe Material options:

select this link for informaiton to address this issue

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Attention: Please see the following AutoPIPE help section:
Help > Contents> Contents Tab> Modeling Approaches> Modeling Approaches>

This help has been provided in order to give users ideas for modeling typical piping arrangements. The steps shown in each example should not be taken as the only method available to create models. In addition, the intent of the examples is to present ways to create adequate models of specific piping components for analytical purposes.

          Anchors        Bends
          Cuts              Flexible Joints
          Frames         Hangers
          Nozzles        Pipes
          Reducers      Rotating Equipment
          Supports       Tees
          Valves           Vessels

Questions and Answer:

Item #1:

Modeling a Nozzle per WRC 297?

Answer: The following fields of data are available when WRC 297 is selected as a Flexibility Method on a nozzle dialog screen:



Enter in values for L1, L2, and Direction of vessel axis to calculate the nozzle flexibility.

Copied from the On-line help:

L1 = distance from the center of the nozzle to either vessel end or to the face of the nearest internal stiffening attachment (e.g., ring).

L2 = Enter the distance to the other end of the vessel (or nearest internal stiffening attachment in that direction).

Meaning, measuring from the center of the nozzle in one direction along the axis of the vessel to a point where the vessel end or vessel internal stiffener ring, enter the value as L1. Repeat the same measurment in the opposite direction along the vessel to a point where the vessel ends or vessel internal stiffener ring, enter the value as L2 (note, L1 and L2 are interchangeable values with regards to the nozzle flexibility calculation, see online help "Nozzle Flexibility Calculations" for complete details). 

Item #2:

Questions: Can you provide more details on the Nozzle dialog fields, Length and Thcikness?

Answer: From AutoPIPE online help:

Length:

Enter the length of the vessel shell wall. Nozzle length is not used in calculated the nozzle flexibility (which is really the vessel shell flexibility). The length defines a flexible joint to which the nozzle flexibilities (as calculated by AutoPIPE) are assigned.

Vessel Radius/ Thickness:

Enter the outside radius (or half the actual diameter) of the vessel and the thickness of the vessel wall in these two fields.

 Additional Notes:

1. Length value = Vessel Shell Wall, which in many cases is the same as the Thickness value. However, be carefull when entering these values, always look to see what units are being used. In English units, Length is entered in FT, where Thickness is entered in INCH.  

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

I am trying to model a 20" STD connection to a tank of 40 m diameter at 1 m above ground level, filled to 13 m high. Naturally I use the API 650 flexibility method (I assume it's using the Appendix P calculations, meant for tanks above 36 m in diameter), but after entering all the requisite parameters, I get the following error:

Clearly I'm missing something, or I'm misunderstanding an aspect of the Nozzle interface. Can anyone please explain what I'm doing wrong? I have entered the following values:

Thanks so much!

Topics under the heading should be based on Warnings found in AutoPIPE:

1. W31-86:   No allowable stresses are available for the selected material in the material library

2. W726-2:  Gap orientation has changed for guide at point XXX

3. W726-6:  Near zero length element at point XXX

4. W726-7:  Pipe diameter change without a reducer at point XXX

5. W726-8:  Kink in straight run of 90.0 deg at point XXX

6. W726-8:  Kink in straight run of 179.9 deg at point XXX

7. W726-38: Allowable at ambient is outside of temperature range at point XXX for material YYYY

8. W726-93: Zero weight flange found at point XXX

9. W726-94: Zero weight valve found at point XXX

10. W726-170:The tee at point A04  has only two legs defined which may not meet the conditions to apply the equations for SIF and other stress indices.

11. W726-195:Support D10  1-Zero length from 'supported' to 'connected' point

12. W727-2: Temperature is outside the range specified the code for Expansion for AutoPIPE

13. W727-3: Temperature is outside the range specified by the code for allowable

14. W774-47 One or more combinations are set to none

15. W801-58:  Smallest timestep for xxxx .TIH file = ....

16. W2018-11, W2018-12, W2018-16: Not authorized for ???? edition

17. W2164-12:System contains Gaps/Friction/Soil data. Please enable non-linear option in the following Analysis sets

18.  

Problem:

The following appears when I select a material on the pipe properties dialog screen, how to resolve?

---------------------------
Warning
---------------------------
 W31-86:   No allowable stresses are available for the selected
 material in the material library, program will use existing data.
---------------------------
OK  
---------------------------
 

Answer:

 As mentioned on the warning message, there is no allowable stresses are available for the selected
 material in the material library, program will use existing data that was preset when the dialog was first opened or use 0.00.

This all means that the material library for the selected material does not have any allowable values. A material library is broken up into 2 or more sections, typically Material section and Specification section. The Material selection has general temperature related data (i.e. Theremal Exp, Young's Mod). However the Specification section had detailed temperature related data (i.e. Yield Stress) that includes allowable stress information.

Example, standard pipe matrial like carbon steel (CS) would be listed in the Material Section, because there are literally hundreds of different types of carbon steels all with different Allowable values. However a specific code code dependent pipe materials like carbon steel ASTM A53-A would be listed in the Specification section of the material library. This material would have documented Allowable values that would be used to populate the various dialog fields required by the program.

In the event this warning message W31-86 appears, you have the following options:

a. Select a different material that has code allowable data in the material library

b. Or, manually enter values for both the Pipe Properties dialog and Operating Press/Temp dialog as required.

c.. Or, accept the default values already populating those locations.

For addied informaiton, please see the following AutoPIPE help section:
Help > Contents> Contents Tab> Reference Information> Libraries>:

Standard Pipe Materials

Code Dependent Pipe Materials

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

The following imported enhancements have been logged for inclusion into a future version of AutoPIPE:

1. CAE-CR-3338 Add ability to model rectangular ducting as equivalent diameter  
   
   Description:  Model rectangular ducting as equivalent diameter.
   
   Development Project:  TBA
   
   
2. CAE-CR-9351 Import CAESAR v.5.3 neutral files
   
   Description: Add option to read CAESAR v.5.3 format. Currently program can read only up to CAESAR v5.2 neutral files.
   
   Development Project: 9.4.0
   
   
3. CAE-CR-11113  PCF Translator: Add feature to select ASME NB piping code 
   
   Description: Add features to select ASME NB piping code from the Piping Code drop down listing and corresponding Material Libraries.
   
   Development Project: 9.6.1.x
    
4. 
   

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Problem:

The following occurs when I run an analysis:

---------------------------
Warning
---------------------------
 W801-121: V-stop liftoff(s) have occurred under operating
 load.  See support output for details
---------------------------
OK  
---------------------------

what shoudl I do?
 

Answer:

This warning occurs when pipe moves in a +ve upward direction off of the support (AKA lift-off has occurred). Another words in the Forces and Moments report, for any combination where the total vertical +ve force is greater than or equal to the Gravity (-ve) force, lift-off has occurred.

a. Please see the following AutoPIPE help section:
Help > Contents> Contents Tab> Bentley AutoPIPE> Frequently Asked Questions> FAQ document> Question 22: When I see the V-stop Lift-off warning message after the static analysis how can I find out where the lift-off is occurring?

b. In addition, Please see the following AutoPIPE help section:
Help > Contents> Search Tab> enter "VStop LiftOff" (include the quotes), press List Topics button, double click on the selected topic from the list provided to see more information

Most programs (at least the popular ones like CAESARII and AutoPIPE) evaluate sustained stress under the cold condition.

AutoPIPE correctly considers the support lift-off effect on expansion stress by evaluating two real operating cases, Hot (i.e. GR+T1) - Cold (i.e GR). When a net +ve up movement is detected a warning for support lift-off displayed. The recommended practice at least by one B31 committee member is to use cold sustained stress (one that ignores support lift-off) when the lift-off is less than about 1/4" as it would be too conservative otherwise and sustained displacements of that order would not constitute failure. The logic of this is that this 1/4" displacement is self limiting like the expansion case and the system would settle to this No-lift-off configuration before it fails.

For large support lift-off, many but not all, engineers tend to delete the supports that have the lift-off, and then rerun for hot sustained stress case. This is easy in AutoPIPE as you can list supports with lift-off using the results grid or support filter.

Results Grid Method:

On the Support Tab of the Results Grid, uncheck all load cases except combinations (i.e. GRT1, etc..) and double click on Global DY column to sort by displacement looking for any value >0.00. If your company procedure requires removal and re-analyze, delete these supports where lift off has occurred and rerun the analysis looking only at sustained stress. After the check, you can then undo this support deletion or save the model as another name if you wish.

Support Filter method :

Please see the following AutoPIPE help section:
Help > Contents> Search Tab> enter "Show lift-off supports" (include the quotes), press List Topics button, double click on the selected topic from the list provided to see more information.

Most designers try to avoid large lift-off because of this issue and so they move the supports or replace with a spring hanger type support. Again, many companies have their own rules in dealing with support lift-off and therefore Bentley does not side with any approach. It is up to the user what to do when Lift-off occurs:

a. Always use cold sustained and ignore lift-off

b. Always remove uplifted supports and rerun for hot sustained

c. Ignore lift-off if less than a certain tolerance, like 1/4" or 1/16".

The ASME B31.3 piping code has a new alternate method (Appendix P) for evaluating operating stresses as well as expansion stresses. This may partially address the hot sustained issue as this sets an allowable for operating loads that include gravity, pressure and temperature. AutoPIPE evaluates these under the hot condition.

In conclusion, Bentley cannot provide you with specific details on how to handle support lift-off. Your company should have standards set in place for such occurrences.

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Comments, Questions, and Answers on AutoPIPE output reports:

Item #1. Results Interpretation

Be sure to review AutoPIPE's online help:

Help > Contents> Contents Tab> Reference Information> Results Interpretation>   

This appendix explains how to interpret AutoPIPE's output report results. The coordinate systems used for the results presentation are particularly important, and are listed first. The output sign conventions for the different result types are then described.

     - Coordinate Systems
     - Total vs. Incremental Loading
     - Pipe Displacements
     - Pipe Forces and Moments: Global Option
     - Anchor Forces
     - Support Forces: Hangers and V-stops
     - Support Deformations: Hangers and V-stops without Gaps
     - V-stops with Gaps and Friction
     - Hangers and V-Stops with Imposed Displacement
     - Two-Point Hangers and V-Stops
     - Straight Pipe Forces and Moments: Local Option
     - Support Forces for Guides and Line Stops without Gaps
     - Support Forces: Guides & Line Stops with Gaps & Friction
     - Two-Point Guides and Line Stops
     - Curved Pipe Forces and Moments: Local Option
     - Support Forces for Skewed Supports
     - Support Forces for Tie/Link Restraints
     - Beam Member Forces
     - Dynamic Support Forces

Item #2. Analysis Subreports

See the following hyperlinks for issue on the respective Anslysis Output sub report:
Command: Analyze model> Results> Output Report:

     - Displacement
     - Support
     - Restraint
     - Forces & Moments
     - Code Compliance
     - Stress Summary
     - Frequency
     - Mode shapes
     - Equipment
     - Soil
     - Bend Angular Distortion
     - Stress Indices
     - Tee Plastic Strain
     - Beam forces
     - General stress
     - Preliminary Stress
     - Accelerations
     - Flange Summary
     - Model listing
     - Analysis summary
     - Steam Relief
     - Reference Loads
     - Fatigue
     - Result summary

Iten #3 Component Data Listing:

See the following hyperlink for issues on the respective Component Data listing (aka Model Input Listing) report:Command: Toos> Model Input listing.

     - Extended Component (Point in v6.1)
     - Coordinates (Component in v6.1)
     - Pipe Properties
     - Material Properties
     - Material Allowables
     - Temperature & Pressure
     - Beam
     - Forces & Displacements
     - Thermal Anchor Movements
     - Seismic Anchor Movements
     - Center of Gravity
     - Earthquake Scale Factors
     - Design Temp and Press
     - Soil Properties
     - Load Summary
     - Support
     - Bend
     - Tee
     - Valve
     - Flange
     - User SIF
     - Reducer
     - Rigid Pipe
     - Reference Points
     - Gross Discontinuity Stress
     - Segments Data

 Item #4: Can AutoPIPE print the Output reports to excel or .csv?

Answer: We apologize for the inconvenience, however AutoPIPE cannot print its reports directly to MS word or MS Excel. Reports are currnetly written to the following files: *.OUT,  *.HGR, *.RPT.

These file can be opened by any text editor (i.e. NotePad, Ms WORD, ect..) . Also, AutoPIPE can export both the Input gids and Results grids to a database file (*.MDB), for manipulation into customized reports.

This enhancement has been logged under CAE-CR-345: Add option to generate reports as EXCEL & WORD files.

 Items #5:

 AutoPIPE Resutls Grids or Output Reports are found to be Zero (0.00) or Blank

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Comments, Questions, and Answers about dynamic support forces in AutoPIPE

Items #1

Question: AutoPIPE: Dynamic Results Interpretation

A. My question is how come the code compliance section does not include both the positive and negative dynamic
results (ie GRTP# +/- R#)? Is there a way to do that?

OR

B. Also, I am confused about how to interpret the local and global forces for the combinations which contain the dynamic support load. Why are the local forces for the dynamic load given as +ve?

TR Number: None
Product: AutoPIPE
Version: n/a
Area: General
Problem ID#: 74535

Keywords:
R1 - R50 Response spectrum cases 1 to 50
H1 - H10 Harmonic cases 1 to 10
M1 - M50 Time history cases 1 to 50
F1 - F10 Force spectrum cases 1 to 10
S1 - S10 Seismic Anchor Movement cases 1 to 10 

Answer:  All dynamic results in AutoPIPE are positive. Since it is the maximum absolute value of the oscillating response.

By reviewing All AutoPIPE dynamic results for the following are reported as positive numbers:

...R1 - R50 Response spectrum cases 1 to 50
...H1 - H10 Harmonic cases 1 to 10
...M1 - M50 Time history cases 1 to 50
...F1 - F10  Force spectrum cases 1 to 10
...S1 - S10 Seismic Anchor Movement cases 1 to 10

For more details on this subject please see the following AutoPIPE help section:

A. Help > Contents> Contents Tab> Reference Information> Results Interpretation> Select the "Results Interpretation Overview" link, at the bottom of the listing select "Dynamic Support Forces" link, read the entire
section for complete details and workaround.

B. Help > Contents> Contents Tab> Reference Information> Analysis Considerations> Modal Analysis> Modal Analysis.

Item #2

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Comments, Questions, and Answers with PCF translator into AutoPIPE:

Note:

Each AutoPIPE translator is installed with a complete manual about the application. See the following file for more details about the translator program:

C:\Bentley\AutoPIPE Translators\PCF Translator \ SmartPlantToAutoPIPETranslator_UserReference.pdf

Issue #1:

PCF conversion worked, but when Import the converted NTL file into AutoPIPE the process aborted: what should I do?

Answer:

See the following link:

http://communities.bentley.com/products/pipe_stress_analysis/w/pipe_stress_analysis__wiki/7642.aspx

Issue #2:

All the AutoPIPE models that we import from Autodesk Inventor PCF files show flanges and valves as weightless “Zero Weight” components. Is there anything that we can do different on our end to have inventor PCF files carry-out the flanges and the valves weights?

Answer: Most common cause is your mapping (pcfin.map). Please see the following folder:

C:\Bentley\AutoPIPE Translators\PCF Translator\

Suggest that you review the all files in this location for complete details on this feature. To answer your question directly, your PCF file is not mapping items correctly. Example of a model that imports a flange without error or warnings:

    ITEM-DESCRIPTION    Flange, CL150, RFFE/SWE, ASTM A182-F304, ANSI-B16.5, S-40S

Recommend adjusting PCF file with a valid description, or fix the map file to import your flanges to anything but the default settings.

If there is no mapping between skey item and type, then default will be applied, default is NS (nonstandard).

Issue #3

Q. When trying to convert a file from PCF to NTL, the converter freezes at “Parsing complete…” it never creates the NTL file.

Answer: Review the PCF file, duplicates of certain components on the same coordinates will cause the connecting logic in translator to hang. Therefor the current PCF file does not  seem like a valid / good PCF file. Open the original model to review duplicate components before exporting a new PCF file to be converted with the AutoPIPE translator.

Issue #4

Q. Program does not import a PCF file and hangs with no error message.

Answer: Review the original model for a closed loop. AutoPIPE does not support a closed loop (segment connected back to itself) and if detected will hang with no error message.

Another common  problem is that the "Description" is too long. Should only be max 60 characters

Example:

 DESCRIPTION    SUPPORT: Rigid Rod with Double Bolt Clamp, Top Type: WELDED BEAM ATTACH, Rod: Cont. Thread, 3/8 $  *PART:Anvil FIG295 1 1/2 in Double Bolt Pipe Clamp, Finish: Black $  *PART:Anvil FIG290 3/8 in Weldless Eye Nut, Finish: Black $  *PART:Anvil FIG146 3/8 in Continuous Threaded Rod, Length: 77.75 in, Finish: Black $  *PART:Anvil 3/8 in Standard Hex Nut $  *PART:Anvil FIG66 3/8 in Welded Beam Attachment (Connect to Bolt), Finish: Black $  *PART:Anvil FIG290 3/8 in Weldless Eye Nut, Finish: Black $

Avoidance: reduce description to smaller size, i.e.:

DESCRIPTION    SUPPORT: Rigid Rod with Double Bolt Clamp,

Issue #5

Q. When trying to convert a file from PCF to NTL, the converter freezes / aborts and it never creates the NTL file, why?

Answer: After reviewing the file, noticed that there are overlapping components which also freezes the PCF translator. The CAE development team will add some programming logic in the next PCF translator build to display a warning message. PCF translator v.1.0.0.29.

Issue #6

Q. Following is displayed when trying to open converted PCF , NTL file in AutoPIPE:

"E880-1: Error in opening import batch file. File extension must be NTL".

Answer: There is a known issue if the file name has a blank space before the file extension, the above message is displayed. Confirm that the file name does not have a blank space before the file extension, example: "Test .NTL", remove space "Test.NTL"

Issue #7

Q. After importing a file into AutoPIPE the components were all found to be missing on a computer with dual monitors and intergrated graphics processor.

Answer: See the following WIKI page.

 No graphical elements found for the components after importing file into AutoPIPE

Issue #8

Q. Branch piping is not connected to the main header pipe on converted PCF file. As seen in the following screen shot, Group 5 (segments F-G) are not connected to the main header of Group 4 (segment D-E). Otherwise it would be a single group.

How to fix this problem? 

Answer: This issue appears to be a modeling problem in the program that created the PCF file. After reviewing the node point coordinates in the original PCF file to be translated, it was determined that there are no points specified on the header pipe for a tee connection.

Fix  the problem by reviewing the original file in the application that created the PCF file to be sure that the piping is correctly connected.  

Issue #9

Q. When importing a PCF file, the single line view looks ok, but actually all the pipe sizes are very large, how to resolve?

Answer: The application ued to create the PCF file did not write the correct units. Example, open the PCF file in any text editor (i.e. Notepad, UltrEdit, ...). See the following component pipe size was found to be 25:

The units are found at the begining of the PCF file:

In this example, the units were found to be INCH. This created a pipe size 25.4x larger than the pipe should have been. To fix this issue, change "UNITS-BORE INCH"  to  "UNITS-BORE MM".

Issue #10

Q. When I open the .NTL file in AutoPIPE, it truncates my pressure values from 2735 to 735 (it omits the leading number). The values appear correct in the .NTL file if I open in a text editor. If I add a space in front of 2735 in the .NTL file, the number shows correctly when imported into AutoPIPE.

Answer: this is a known issue and was fixed in a new relase of the applicaiton, PCF translator v 01.00.00.36 (CAE-TR-11101

Issue #11

When running the PCF translator the following orccurs:

Bentley PCF Translator (Not Responding)

What shoudl I do?

Answer.When using the PCF translator, select the file to be converted, make additional changes to all the other settings as needed and press the Convert button.

After pressing the Convert Button, suggest that you remove your hands from the keyboard and mouse. The translator is using a significant amount of system resources to convert the file. Some files that are converted have over 100,000 lines in one file. By pressing a button on the keyboard or mousing over something system resources are taken away from translator. Sometimes when this happens the application will show the Not Responding message and become grayed out, as seen above.  However the software is still trying to recover and complete the conversion process. Again, do not touch anything. Most of the time the application will complete the conversion, the PCF  translator will no longer show the Not Responding message and you will be able to open the newly converted file in AutoPIPE.

No mater the size of the model, be patient and let the application complete the conversion before moving onto another task. Again, this application is sensitive to system resource allocation. Regardless, if the model is converted and can be opened by AutoPIPE, everything should be ok, continue working on your analysis in AutoPIPE.

IIf this issue occurs alot, you may consider adding more Ram or a beter CPU.

Also, if after an extreme amount of time, the Not repsonding messag is still visible, close the application, file a service request, and send Bentley the PCF file you are having troubles with for review.
 

Issue #12

Below are general questions and answers about the process  of exporting an existing AutoPIPE model (DAT) to a PCF file, translate the newly created PCF file with the PCF translator back into an AutoPIPE model, and compare AutoPIPE results between before and after translation:

Q1.   The expansion joint are not support in the current PCF translator

A1. Support for Flex/Expansion Joints were implemented in PCF translator 1.0.0.24. Can You please use the latest release of PCF Translator. You can get the newer version of translator from ftp://ftp.bentley.com/pub/tools/fixes/autopipe/PCF_Setup_1.0.0.25.exe (Dec 2012).

Q2. The pipe is oriented 180 deg from original

A2. Before export to PCF from AutoPIPE, In AutoPIPE  Go to Tools> Settings > Isogen Settings

Change North arrow to +X then the coordinates matched exactly

Q3. Pressure and Temp are different from before to after, example: 10 deg & 100 psi converted to 0.0 deg  & 0.0 psi

A3. This is a limitation in AutoPIPE PCF Export, which does not write Pressure and Temperature and hence default values are used.

Q4. Pipe properties changed; wall thickness changed sch 160  changed to STD and Pipe material, from A335-P91 changed to A106-A

 A4. There is a limitation in AutoPIPE PCF Export could not correctly map the material and by default A106-A with STD wall thickness has been used. Adjust the map file as required to correctly map the material and wall thickness.

Q5. Extra support (V-stop)  added to the converted file at origin point with anchor.

A5. During first time Export to PCF. AutoPIPE write Anchors as a Support with SKEY 01AN and then on import this support component converted to an default support V-STOP. Manually delete V-Stop.

Q6. Flanges converted for the expansion joint are in the wrong location.

A6. This has been fixed in a newer version of the translator, upgrade to the latest version of PCF Translator, v1.0.0.32.

Q7. Tee SIF values are different (because of wall thickness issue above, Q4)

A7. Yes, proper schedule has not been exported by AutoPIPE in PCF. update PCF map file accordingly.

Q8 Bend radius is different

A8. Bend length is exactly same but after import from PCF the actual radius has been written instead of "LONG"

Q9  I cannot get the PCF translator to exectue from the command line (Batch Processing) as mentioned in online help info, why?

A9. This passage was not suppose to have been printed in the published documentation because this feature had neever been added to the program. This wae info was removed in the new version of the documentation.

See Also

Bentley AutoPIPE

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to
the "Comments" area below. THANK YOU!

Error or Warning Message

The following warning appears when inserting Nozzle, how to resolve?

---------------------------
Warning
---------------------------
W41-27: Parameters are outside the applicable range
---------------------------
OK
---------------------------

Answer

One should understand the limitations of the WRC code:
WRC107:
   a. d/D <= 0=0.33 (subsequent revisions extend d/D <= 0.50)
   b. D/T <= 600
   c. Spherical shell limit: d/D = 0.33

WRC297:
  a. d/D <= 0.50
  b. 20 <= D/T <= 2500

where:
  d = outside dia of nozzle
  D = outside dia of shell
  T = shell thickness

Each method has a limited applicability based on certain parameters. Unfortunately AutoPIPE does not mention which limit caused the message. Values shown may still be reasonable outside the range. You may try other methods such as ASME or Bijlaard.

API650 method
================

API 650 Method is limited to horizontal nozzles on vertical tanks of diameters in the order of approximately 100 ft (large tanks). For nozzles on the spherical or torispherical head, you need to use "Spherical" nozzle option. As ASME method is typically meant for reducing tee branches.

You would need to check the code to see the formulas. Actually they are plots.

There are limits on these 3 ratios for API 650:
ALFA = Vessel radius/Vessel thickness
BETA = Nozzle radius/Vessel radius
GAMA = NOZZLE LOCATION ABOVE GROUND LEVEL/(2*NozzleRadius)

Limits are exceeded if:
  1 = ALFA > 2300
  2 = ALFA < 400
  3 = BETA > 0.04
  4 = BETA < 0.005
  5 = GAMA > 1.5
  6 = GAMA < 1.0

For those who do not have a reinforcement pad for the nozzle, try other options (WRC297 or Bijlaard) and use larger stiffness to be conservative.

WRC297 method
================

Autopipe is considering limits of the WRC297 stiffness curves on Fig 59 and 60 (Copies attached) and giving a warning if any of these limits is exceeded. The program proceeds to calculate stiffnesses at the last known curve value which may or may not be valid.

Radial, longitudinal and circumferential stiffness Lambda < 0.1 Lambda > upper limit of curves

where: Lambda = (d/D).SQRT(D/T)
  D - vessel mean diameter
  T - thickness of shell <<<<< Is this including or not including re-pad thickness if there is one?
  d - nozzle mean diameter
  t - nozzle thickness

Longitudinal stiffness
  T/t <0.2 or T/t > 10

Circumferential stiffness
  Delta > 100 or Delta < 14
  T/t < 1.0 or T/t > 10

delta = L/sqrt(DT)
  L = length of vessel
  L = 8L1L2/((sqrt(L1) + sqrt(L2))^2) - for off-center nozzle

Note: WRC297 has no concept of reinforcing pads, the thickness field in the dialog is for shell only (i.e. uniform shell thickness). If you enter shell + pad thickness, this would be stiffer and more conservative to calculate the nozzle flexibility.

Bijlaard method
================

Bijlaard Nozzle limits
Cylindrical

gama > 15 (murad and sun limits 10-150, 15-300 in bijlaard figs)
beta < 0.55 (0.55 in murad and sun paper, 0.25 in bijlaard figs)

Where:
  gama = rad / th
  beta = c / rad

c = nozzle outside radius
rad = vessel outside radius
th = vessel thickness

Spherical

1. u < 20 curve values
2. r/t > 15 page 3 of paper
3. ro/r < 0.55 (murad and sun curves - cylindrical)

rad = outside radius
t = thick `vessel thickness <<<<< Is this including or not including re-pad thickness if there is one?
r = rad - 0.5*t `mean radius of vessel
ro = piprad/2.0
nu = poison
e = ymod
c1 = (12.0*(1.0-nu^2))^0.25 ! c1=1.81784 for nu=0.3
u = c1*ro/sqrt(r*t)

Any one?

That answers my question, thank you!

Can somebody remind me the meaning of + and - Node points that AutoPipe shows stresses for the same physical node point.

cheers 

Dear all,

Where can I get from output report meaning of initial operational load case  I have defined before (see screenshot)?

I received a comment from the client «This liberal equation shall not be used. This feature shall be turned off in the software».

Аs ASME 31E said,  I can use two variants for choosing seismic load direction: one is three directional excitations such as plant east-west, north-south and vertical, with the combination of square-root sum of the squares (SRSS) or two directional

design approach of based on the envelope of SRSS of east-west plus vertical and north-south plus vertical seismic loadings.

According to this definitions, the former is as follows if X is east-west direction and Y is vertical with the maximum design acceleration being 0.3 in horizontal and a half in vertical:

E1: -0.212 0.15 -0.212.

E2: 0.212 -0.15 0.212.

Also if the gap or lift-off is to be considered in piping system, you should add positive and negative direction for each X, Y and Z direction with normal operating condition such as W+T1+P1, that means W+T1+P1+E1.

Do I correct understand?