UG-45 minimum nozzle thickness 3

[Shmulik]

For what stand-out length of nozzle does this requirement apply? For what outer length a nozzle is still been defined as a nozzle?

Does this length limited to the UG-37 Limit of Reinforcement (2.5t or 2.5 tn+te)?

How about threaded or Victaulic connections? Are these types permitted when remained thickness at connection's area does not comply with UG-45?

Thank you for your help!

 

[eliebl]

With the Victaulic connections be sure that they are acceptable per Appendix 24. It should be noted that this is a mandatory appendix.

As for UG-45 minimum thickness, this would apply to the entire nozzle length. Essentially where it changes from vessels scope as a nozzle to piping scope.

If I remember correctly these requirements are based upon the fact that small nozzles are typically used for climbing on or around the vessels.

 

[GenB]

"Does this length limited to the UG-37 Limit of Reinforcement (2.5t or 2.5 tn+te)?"
I believe that the par. limits calculated nozz. reinforcing,
beyond 2.5tn

 

[jte]

You have to go back a ways, but I believe the following interpretation answers your question. On a related topic, I believe the 2010 Edition will have substantial editorial changes to UG-45 [it'll look completely different, Div. 2 style] to make it more user-friendly. I'd say a fitting which is otherwise qualified for use on a Div. 1 vessel with no pipe or rolled plate nozzle neck does not fall under UG-45.

jt

Interpretation: Vlll-1-83-217

Subject: Section Vlll-1, UG-11 and UG-45
Date Issued: February 22, 1984

Question: Are threaded couplings welded directly to a pressure vessel to be designed per ANSI B16.11 as stated in UG-11, footnote 5, Section VIII, Division 1, thus disregarding the requirements of UG-45 for nozzle neck thicknesses, since no neck exists?

Reply: Yes.

 

[GenB]

still when calculated the limitation does not go away you cannot take credit beyond the reinforcing limits stated

 

[SnTMan]

Agree w/ eliebl, UG-45 has nothing to do with opening reinforcement, but with mechanical strength of the nozzle. It applies to the entire nozzle.

Regards,

Mike

 

[Shmulik]

eliebl / jt / Mike: thank you for reply.

How would you consider a nozzle made of a pipe with external threaded end? What is the minimum wall thickness required under thread? Is it acc. to UG-27 or acc. to UG-45?

Does the following requirement apply also for nozzles?
"UG-31 (2): Where ends are threaded, additional wall thickness is to be provided in the amount of 0.8 /n in. (20/n mm)"

What is the meaning of "additional wall thickness”? What is the basic min. thickness it added to?

 

[eliebl]

Nozzle min wall comes from two calculations. First and formost is the thickness required for pressure. Then a check needs to be done to be sure that it meets the requirements of UG-45.

If the end of the nozzle is threaded, the thickness available for either calculation is the minor diameter after the threads are cut. I don't see any other way to calculate the minimum required thickness.

Also, be sure that you keep UG-16 in mind. Although it is unlikely to impack a nozzle it is an area that seems to be missed all too often.

EJL

 

[SnTMan]

Shmulik, it is my opinion only, but I think the threaded portion could be excused from UG-45. However, if considering this it would be best to confirm with your AI.

Regards,

Mike

 

[vesselfab]

Pipe with external threads on nozzles is really bad practice. It is too easy for the threads to get "boggered" up and not continue to seal.

I have not seen this done in years, but then again, most plants don't allow it anyway.

anyway, the minimum wall thickness...std wt plus ca or shell min thick plus ca....is anywhere in the nozzle.

code does not say that it stops anywhere.

on couplings, I use only 6000# threaded couplings, when client uses couplings, because the wall thickness under the threads is large enough to meet the minimum wall thickness and there is les distortion when welding into shell. And we use many extended length weld in couplings to get the threads outside of insulation and away from shell attachment welds

sometimes it is the little things that make a quality vessel.