How to model a Socket welded or threaded fittings (i.e. Bend, Tee, valve, Sockolet, Threadolet, etc..) in AutoPIPE?
Apply manufacture recommended SIF values or refer to a specific piping code for recommended SIF values to be applied piping component
The intent on many ASME codes to use conservatively an SIF value = 2.3
The intent on many ASME codes to use conservatively an SIF value = 2.1
ASME Codes state the following regarding socket welds:
B31.1 use 1.3 for socket welds with no undercut, and 2.1 for all others.
B31.3 states "2.1 Max or 2.1 T/Cx but not less than 1.3. Cx is the fillet weld leg length"
B31.8 states "2.1 Max or 2.1 T/Cx but not less than 1.3. "
Press Select> Bends> to highlight all bends in the model,
Press Select> Tees> to highlight all tee in the model
Press Insert> Xtra data> Joint Type and User SIF> select "Joint End Type" = (select 1 of 10 choices) (ex. "Socket or Fillet Weld ", " Threaded Joint")Note: 1. see AutoPIPE help for a complete list of options available for selection. 2. For joint types not listed select "User-Defined" Manually enter the "Inplane SIF" = (manufacture / code recommended value, ex. 2.1) Manually enter the "Outplane SIF" = (manufacture / code recommended value, ex. 2.1)
Optional: select "Override all other SIFs at this point", see AutoPIPE help for details on this option.
Press OK button to apply SIF values to all highlight components.
Create a new pipe property with the correct wall thickness
Press Select> Bends> to highlight all bends in the model
Press Select> Tees> to highlight all tee in the model,
Press Modify> "Pipe Properties over range", select the new pipe property ID, and press OK button to assign the new pipe ID to the selected components.
As an example, according to ASME B31.3 - 2014 sec. 320.1, Basic Assumptions and Requirements Sustained conditions may be evaluated by detailed analysis, approximate methods, or simplified means such as span tables.
Section moduli used to compute the stresses in this paragraph shall be based on nominal pipe dimensions less allowances, i.e., the sum of mechanical (thread or groove depth), internal and external corrosion, and erosion allowances.
The code continues with formula that include the SIF's
Again as an example, in AutoPIPE , using ASME B31.3-2014, section modulus is calculated using the nominal thickness less corrosion allowance if "Use Nominal Thickness" is unchecked. Pipe Property "Mill tolerance" is not considered ever for B31.3 section modulus calculations.
Therefore, when applying an user SIF, by setting "Joint End Type = Threaded Joint" will affect only the SIF and not the section modulus,
Adding the corrosion and thread / grove depth together, placing that value in the corrosion field of the Pipe Properties dialog should calculate the appropriate section modulus for all pipes using that Pipe ID.
Bend & Miter Piping Components - Modeling Approaches, Tips, Techniques