Where does a Nozzle end and a Pipe start?

[BrentP]

Have a question as the title says, I have a vessel where the nozzle is a machined 1.5" XXH pipe. The pipe is tapered at the end from .265" to 0.063", where a flange is added and another pipe bolted to it.

So, my question is, which portion is the code dependant portion, the 0.265" which is 2.7" long and the shell to weld thickness, or the 0.0625 section which is the end and extends only 0.5" but has the flange welded to it?

If it matters, calculated required thickness s around 0.035"

Thanks

 

[mk3223]

IMO, the Code vessel should include the nozzle flange which is welded to the 1.5" pipe section as fabricated and tested in the shop.

 

[keyen]

What is the code of construction you're working with?

Per ASME Section VIII-1 paragraph U-1(e)(1)(-a):

(e) In relation to the geometry of pressure-containing parts, the scope of this Division shall include the following:
(1) where external piping; other pressure vessels including heat exchangers; or mechanical devices, such as pumps, mixers, or compressors, are to be connected to the vessel:
(-a) the welding end connection for the first circumferential joint for welded connections [seeUW-13(i)];

The emphasis is mine.

 

[racookpe1978]

How (why!) the bloody Hades did you cut the pipe wall down from 0.265 to 1/16 inch for welding at the 1/16 inch thickness to the far-thicker nozzle flange itself?

Show the geometry of the entire flange and weld and both nozzle-to-PV wall and nozzle-pipe-nozzle flange. This makes no sense at all.

I disagree with the above "code definition" of the attachment welds and PV nozzle definitions. Not because the interpretation of the words is necessarily wrong, but because the "Code" is NOT written to assume your sub-standard/none-standard removal of 3/4 of the nozzle wall thickness. The Code is written to define minimum standard welds, pipe wall thickness (so the stress distributions and movement and strains are predictable!), and so the entire PV pressure barrier withstands the historical "normal" variations of "normal" real-world nozzles under "normal" not-anticipated excessive stresses and strains.

The PV Code is written in blood. Stay on the safe side of it's assumed configurations, not on what you judge to be the "legal interpretation" of its words.

 

[gr2vessels]

BrentP,
Assuming the design code is ASME VIII-1, the guiding clause is UG-45. That will tell you the minimum nozzle neck thickness, if your 0.063" is acceptable or not. The nozzle thickness is not dependent of the nozzle length. The attached flange rating should cover the vessel MAWP at temperature, but does not have effect over the nozzle minimum thickness.
Cheers,
gr2vessels

 

[SnTMan]

Better have a look at UG-16 as well.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[BrentP]

Hi folks, I swear I had notifications on, but I received none.

The vessel is a lyophilizer, in stainless. Its a commercially purchased vessel, and I believe the nozzles are reduced to match the BPE piping that attach to the vessel.

I have an entry knowledge into ASME VIII, so I'm thinking the XXH pipe is to deal with the strength/weld portion of the code as well as the Tmin must be at least the thickness of a STD pipe, and the Machined portion is to satisfy UG-16, so 0.063".

As I said, the vessel is with in all code requirements, but they are using a UT program that predicts a remaining life, so a retirement limit needs to be entered. If a bare minimum of Code 0.063 less 12.5% mill tolerance is entered for 0.055" regular variations in fabrication and UT will cause alarms due to under values.

Company needs a retirement limit, and wondered if a value of say 0.050" would be acceptable as calculated tmin for pressure is 0.035"

Again, thanks for the replies.