Which equation does autopipe use for stress for linear and non-linear calculation? Does autopipe use these concepts as cold allowable, yield strength, UTS, long and hoop modulus, shear modulus, ... for calculating stress? Thank you very much

Equation for calculating stress in autopipe

  • Good day to you Thang, 

    When creating a  model in AutoPIPE, the user must enter Pipe properties and Operating conditions (Press, Temp, etc..). When performing an analysis the user must determine which piping code is to be used for the analysis, in addition, select the type of analysis is to be performed; Linear or Non-linear.

    With this in mind, see answers to your questions:

    Q1. Which equation does autopipe use for stress for linear and non-linear calculation? 

    Answer:

    It does not matter if using Linear or Non-linear method, the stress calculations are the same. The stress calculations are based entirely on the selected Piping code + Year. Please see the following AutoPIPE help section:

    Help ribbon> Contents button> Contents Tab> Reference Information> Code Compliance Calculations> choose a piping code + year, select a topic to see the equations used by the program. 

    Q2. Does autopipe use these concepts as cold allowable, yield strength, UTS, long and hoop modulus, shear modulus, ... for calculating stress? 

    Answer:

    Yes, the various pipe properties and operating conditions information are used by the program as called for by the code equations. 

    Regards,

    Mike Dattilio
    Bentley Systems Design Analyst
    Design Engineering Analysis group
    ===================================================

    Answer Verified By: Mike Dattilio 

  • Thank you for your answer, I checked the equation for code compliance calculation for power piping related to my current field (environment project), but these equations seem to be very hard to understand.

  • Hello Thang, 

    it is actually very simple, each code compliance calculation has a category, ex. Sustain, Expansion, Occasion, Hoop, 

    In AutoPIPE help, mentioned above, each piping code and year has the same categories

    - Stress Due to Sustain

    - Thermal Expansion Stress

    - Stress Due to occasion Loads

    -Hoop Stress

    -etc..

    On each page, the calculations are shown, with or without variables information. If variable information is missing, see Definition of Terms hyperlink at the bottom for more details. Otherwise, read the entire page to understand why AutoPIPE may use one equation over the another. It would usually depend on settings or modeled component. 

    Example, in screen shot above, Hoop stress will be calculated base on the 1st equation. However, the 2nd hoop stress calculation will be used for Closely Spaced mitered bends, or use the 3rd hoop equation for Widely spaced mitered bend components. 

    Furthermore the page provides information about how AutoPIPE calculates the Allowable. It is very important for the user to read the entire page for understanding of the calculations being performed. Take extra time to read all Notes as they contain valuable information. 

    Regards,

    Mike Dattilio
    Bentley Systems Design Analyst
    Design Engineering Analysis group
    ===================================================

     

     

  • Thank you for your answer on this issue. Then I can see the necessary equation and valuable information. But they seem to be very difficult to understand. So I think we just need to master the general concept and do not need to understand all the information in each equation autopipe provide, it is enough  for analyzing stress in autopipe. Do you think it is right?

  • Do you have an engineering degree? Whoever teached you that you should only understand a 'general concept', is wrong. Of course (it is important that) you need to understand what the program does. AutoPIPE is a tool, and as a designer or engineer, it is up to you to use the applicable tools to make sure the design is right (and acc. Code)