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'Set-in vs set-on' strikes back!

ElCidCampeador

ElCidCampeador

Mechanical
May 14, 2015
274
Hello, I've read many threads in this forum about set-in/set-on nozzles and what is the "best" solution for a pressure vessel.
I usually design according ASME VIII Div.1 but this code seems not to suggest a preference for a insert or a set-on configuration as long as you follow figure UW-16.

But from a "SIF" point of view, it seems to me that a set-on weld is worse than inserted. Do you know any research paper or standard that I can read about?

I've read B31J (which was appendix D of ASME B31.3) , e.g. table 1-1, but I don't understand sketch shown and "Run SIF" defined. What am I supposed to take away from all this? Please help me, thank you.
 
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You can have a look at note (8) of B31J. Looks like from the first sentence that insert are better for SIF, since you automatically multiply them by 0.7.
 
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You can have a look at note (8) of B31J. Looks like from the first sentence that insert are better for SIF, since you automatically multiply them by 0.7.
Click to expand...
mmm I don't understand where you can see the difference between insert and not. This note refers to figure 1-3 which is very general and not regarding a difference between type of weld but more about "shape" of the joint...
 
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Example: shell thickness 200 mm, nozzle NPS 2.
How do you design this weld?
 
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In table 1.1, 2.3, if you look at the schema there is a radius r2 for the insert nozzle. Under it there is a direct reference to note 8, which is not the case for the set-in nozzle. That's why i though this note was only for insert nozzle, but i think you're right it is more general than that. So i guess SIFs are the same for set-in or insert, so probably no difference in design between both.
 
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Example: shell thickness 200 mm, nozzle NPS 2.
How do you design this weld?
Click to expand...
Simple: I input dimensions in my software, I guess a weld dimension, then if software whines I change weld dimensions until it works! :)

In table 1.1, 2.3, if you look at the schema there is a radius r2 for the insert nozzle. Under it there is a direct reference to note 8, which is not the case for the set-in nozzle. That's why i though this note was only for insert nozzle, but i think you're right it is more general than that. So i guess SIFs are the same for set-in or insert, so probably no difference in design between both.
Click to expand...
I've read that set-in can manage higher stresses than set-on...so is this not related to SIF?
 
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@ ElCidCampeador

I do not know if you really understand the difference.
a)Did you understand my example?
b)Why the SIF is the same in set-in and set-on nozzle attachment, as you say?
c)Why do you mix ASME VIII Div 1 (pressure vessel) with ASME B31.3 (piping)?
d)Why not read ASME VIII Div. 2?
e) Why do not you mention about welding and NDE?
 
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ElCidCampeador said:
I've read that set-in can manage higher stresses than set-on...so is this not related to SIF?
Click to expand...
I don't see any difference in the calculations or SIF if your weld is integral (full penetration) and dimensions are essentially the same. If you also performed lamination check beneath the set-on nozzle and it is acceptable, then no strength reduction there.
 
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Nobody mentions NDE, do you think it's not necessary?
SIF calculation without NDE?
 
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@ RadiateurFou
See again my Example
"Example: shell thickness 200 mm, nozzle NPS 2.
How do you design this weld?"

You need to read more about pressure vessels. I don't know what NDE means to you.
 
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Now I'm sure you don't understand what Nondestructive Examination is.
 
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