Opinions Wanted: Fitting Under Sec VIII, Div. 1 1

[SnTMan]

I had a (nearly wasn't) hypothetical situation recently concerning use of reducing tee as a shell eleement. The proposal was to use a 24" X 16" reducing tee as part of a 24" shell w/ 16" nozzle to avoid fabricating the large opening.

Question is: Is the tee inherently adequate without considering the opening, under UG-44, or is it treated as a flued opening under UG-38 and UG-37?

Any interpretations, etc to support your view?

TIA,

Mike

 

[pdiculous963]

I would say that it is acceptable. UG-11(a) states that parts that comply with a ASME Product Standard are acceptable at their pressure temperature rating, unless modified by UG-44. UG-44 states that the pressure-temperature rating for pressure parts fabricated to B16.9 should be calculated as straight seamless pipe in accordance with the rules of Div. 1. If you performed the calculations using the thickness of the reducer and the dimensions of the 24 inch side, you would be satisfying the code.

 

[pdiculous963]

Edit: You should also do the calculation for the 16 inch side if it is thinner than the 24 inch.

 

[GenB]

Is the material specification of the tee acceptable for shells?

 

[SnTMan]

GenB, well, yeah. For this discussion suppose it is any fitting spec allowed for Sec VII, Div 1. Further suppose wall thickness is the same for run and branch, to address pdiculous963 2nd post.

What then? Is it inherently reinforced? Is it a flued opening?

Regards,

Mike

 

[metengr]

SnTMan;
In this type of grey area of the code, my expectation is to go the more conservative route. This means I would expect this would fall under a flued opening requiring supporting calculations.

 

[SnTMan]

metengr, I have on other designs with small openings condsidered a tee to be inherently reinforced, didn't think much about it. I am sure it is pretty common. However for the hypothetical large opening, I thought to consider it more carefully. Currently I am leaning your way although I doubt certain of my co-workers would agree.

All well and good to prove it per UG-37, however some practical complications may exist related to size of opening (variable), limits of reinforcement, particularily along opening axis, nozzle thickness required, excess available, and so forth.

I suppose it might be reasonable to just treat it as a fabricated opening, as stress concetration would obviously be much lower in the tee.

As you said, grey area, but this must have come up before, I am hoping for some relevant "history" either way

Regards,

Mike

 

[GenB]

SnTMan. What I ment was that B16 Material may not be acceptable for shell of pressure vessels.
Check UG-4 through UG-9

 

[SnTMan]

GenB, most commonly would be SA-234-WPB or SA-403-3xx, both permitted for Sec VIII, Div 1 under Sec II, Part D, Table 1A.

Regards,

Mike

 

[GenB]

SnTMan. If the material specification is acceptable in UG4 thru. UG9 for the fabrication of shells and heads of pressure vessels, then go ahead with your project.
Forget section II, that's irrelevant. good luck.- GenBlr

 

[sathikn87]

SnTMan, As per UG 11(C), fittings under UG 16.9 are pressure parts that comply with ASME product standard accepted by reference in UG 44.
As per UG 5(C) pressure parts, such as standard pipe fittings, welding caps, and flanges that are seamless or fabricated by one of the welding processes recognized by this division do not require inspection.

As per UG-44 thickness for the fittings conforming to B16.9 shall be calculated as a seamless pipe with the manufacturers tolerance applied.

The pipe fittings including Tees are generally hot formed and are exempt from heat treatment requirement due to fiber elongation (see SA-234 in Section II, Part A and UCS-79).

 

[SnTMan]

sathikn87, so shall the opening be considered as per UG-38?

GenB, Sec II irrelevent? Don't think so.

Regards,

Mike

 

[sathikn87]

SnTMan,Well, I think you should consider UG-38. anyone have different opinion??

 

[sharmass]

Its a standard pipe fitting complying with ASME B16.9
Only UG-44 is applicable. UG-36 thru 38 do not apply
Design the fitting considering 24" pipe. Apply 12.5% negative tolerance while calculations
Make sure that the Tee is not modified (don't reduce length or height)otherwise the Tee shall be considered as non standard.