| Applies To | |
| Product(s): | AutoPIPE |
| Version(s): | ALL; |
| Area: | Modeling |
| Date Logged & Current Version | Feb 2023 23.00.00.230 |
Problem:
Q. 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?
Answer:
Basically, there are two scenarios’:
- If you tick Apply B31J General Note (d). then the AutoPIPE will check all the 3 conditions given in B31J General Note (d) and give you the SIF for the same.
For e.g.:
In your 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.
- If you don’t choose “Apply B31J General Note (d).” then the AutoPIPE will go for B31.3 code.
For e.g.
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) gives the same effect as the elbow then, in that it keeps my user-defined SIF? Just tried that and it doesn't.
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.”
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