How do I get my SIF values into code calculations for tees and where is autopipe getting these SIF ?


 

Applies To  
Product(s): AutoPIPE
Version(s): ALL;
Environment: N/A
Area:  
Original Author: Bentley Technical Support Group
Date Logged
& Current Version		 Sep. 2024
23.00.01.367

Problem:

I need to override stress intensification factors at all fittings, and I've done that by inserting User SIFs. When I study analysis results, bends and reducers appear as I intend, but tees do not.  I'm not even sure where the tees are getting their SIF because they don't match what is in the 'review component data' grid either.  I've also tried unreinforced type tees automatic SIFs and "other" type with user entry in the grid, but that doesn't change anything.  How do I get my SIF values into code calculations for tees and where is autopipe getting these SIF values otherwise if it's not using my override?

Solution:

Let me explain you how this functionality works:
Basically, there are two scenarios':

  1. If you tick Apply B31J General Note (d). then the AutoPIPE will check all the 3 conditions of General Note (d) given below and will give you the SIF for the same.
    (a) 0.75 times the applicable stress intensification factor.
    (b) (t/T) times the square root of the applicable stress intensification factor when t/T > 1
    (c) the square root of the applicable stress intensification factor when t/T ≤ 1

    In you case the t/T ratio is less than 1 therefore this satisfies the 3rd condition.
    The user defined SIF for node G35 Header is 4.38 as per condition 3 the resultant SIF is the square root of 4.38 which is 2.09. Similarly, happens for the branch SIF also.

    A screenshot of a computerDescription automatically generated
  1. If you don't choose "Apply B31J General Note (d)." then the AutoPIPE will go for B31.3 code.

    In your case the user defined SIF for node G35 Header is 4.38 and 0.75 time 4.38 is 3.29 as you can see in the screenshot below. Similarly, happens for the branch SIF also.


Question. Wouldn't changing the tee type to "welding" (sketch 2.1 of B31J) give the same effect as the elbow then, in that it keeps my user-defined SIF? 
Answer. As per the statement in B31J Gen Note d. "the components of sketches 2.1 through 2.6 the direction sustained stress or moment multiplier can be conservative taken smaller of the 3 conditions." Refer the screenshot from Help AutoPIPE given below:

So, if you change the tee type the effect will be same. Because sketches from 2.1 through 2.6 is covered under this note. 

See Also

"User SIF" - sub-report

Bentley AutoPIPE