What determines where a nozzle of a PV stops and the piping begins?

[FIS4224]

I know a nozzle is a component of a pressure vessel, what I am not clear on is where it stops being a nozzle and becomes piping.
Is it to the first joint regardless of the following connections?

Example; if the fist joint after the Cat "D" shell attachment weld is another weld and the following joint is a breakable conection such as a flange or threaded joint where does the piping start? Is it at the first welded joint or the breakable joint?

Can the nozzle include as many as three welded joints before a breakable joint and still be considered a nozzle?

 

[XL83NL]

Refer to para 300.1 of B31.3, and U-1 of ASME B&PV VIII Div 1. It's a few pages of reading, I did it last week. Since I had the same question, I just scanned it quickly, and believe you'll find your answer in those 2 sections.

From what I remember, there is some overlap to give the engineer/designer some room for buffer, i.e. at the connection/joint of piping to vessel (let's say at the PV"s nozzle for example), you may e.g. interpret the vessel's nozzle as both piping and PV. But, Im not 100% sure though.

 

[JStephen]

It would be advantageous if everything furnished by the vessel fabricator were considered "vessel".

 

[FIS4224]

thanks will take another look

 

[chicopee]

I think that the answer should be obvious during the erection stage of the boiler and its piping.

 

[FIS4224]

It is still not real clear in the code sections you referenced XL83NL. I think it comes down to the engineering behind the vessel that determines the nozzle end point.

Not sure what your talking about chicopee I'm not refering to boilers. If you meant pressure vessels how is it obvious to the in-service inspector who is not present or made aware of the instalation conditions of the pressure vessel?

 

[RossABQ]

Are you suggesting that a portion of a nozzle should be designed/tested as piping, to a different standard than the nozzle portion of the same piece?

 

[XL83NL]

@ RossABQ;
I dont think that should be the case, but acc to the requirements of B31.3 for hydrostatic leak testing of piping, vessel nozzles and even complete vessels, for the scope of piping leak testing, may be regarded in the piping scope. So there are some 'exceptions'.

 

[zcp]

Thought it was first flange or (if no flange / joint) first weld.....in your case it seems like it should be the flange / threaded joint which would include the welds.

ZCP

http://www.phoenix-engineer.com

 

[TJOrlowski]

It is up to you, your customer, and the fabricator making the vessel (with out without removable pipe spools) to determine where the job stops being governmed by Section VIII, Div.1 and starts being governed by B31.3.

Generally, if a flange or nozzle is welded to a component(s) governed by VIII, Division I, then the flange or nozzle should also by governmened by VIII, Division I. If a pipe spool, or other removable component is in question, then the governing code should be determined by mutual agreement between all concerned parties.

-TJ Orlowski

 

[mowlin]

I agree with ZCP.....

 

[FIS4224]

TJorlowski I tend to agree with you, unfourtunately I do not usually have access to MDR's. In your opinion if a nozzle with a short projection welded to and elbow than a flange would it not make more sence to call all three compnents part of the nozzle even if there is as many as three welded joints included?

For example I inspect many separators, scrubbers and contactors with this configuration so if the vessel is ever moved to a new location obviously the three component part of the nozzle goes with the vessel and new piping will be connected at the first flange or threaded joint.