Nozzles with internal NPT thread made from bar

[Lukasz1]

Hello Everybody

I have a question regarding nozzles with interlnal 2,5" NPT threads made from bar.

I know that i must fallow rules listed in UG-27 and UG-45, but i have also read 2148 Code Case and this caused my doubt.

My question is: do i have to make sure that wall thickeness after internal threading in the thinest part of the nozzle is the same as for 2'5" std wall pipe?

This is pretty clear when u have nozzles with external threading but when it comes to internal threading i don't know if i understand it correct because very often we dont have standard outside diameters as for pipes. I would like to be sure of this, because i want to make some nozzles with smaller outside diamater and i don't know if am allowed to even if rules from UG-27 and 45 will be met.

Lukasz

 

[GenB]

caution: internal threads are not the same as external,
it is my opinion that you have to use standard B16 internal threaded connections
if you wan a long nozzle with threads I sugest you weld a std
B16 to a pc of pipe.

 

[Lukasz1]

Hello once again

Thank you all for your responses

I will try to be more precise now and use an example.

Lets pretend that i want to make 2,5" NPT - internal nozzle from fi 85mm rolled stainless bar. I checked the rules in UG-27 and UG-45 and apllied them in my calculations. I also read the 2148 Code Case and noticed very interesting sentence in point (b):

When nozzle neck is greater than NPS 4, or nozzle nominal wall thickness is less than that for standard wall pipe, or the design hoop tension stress is greater than 50% of the allowable stress value, the material shall be formed into ring.

I am interested in that nominall wall thickness thing. As i understand it now i need to compare my 85mm outside diameter of the bar to the closest larger pipe size and check it STD wall thickness. For my example it's 3,5" pipe with STD 5.74 mm wall thickness and this is my nominal wall thickness which nozzle should have after threading.

I would like simply to know do i understand it correctly, because from requirements included in UG-27 and UG-45 i calculated that i could use smaller wall thickness and make outside diameter of the nozzle smaller like 82mm (for more space). I don't know if i am allowed to because of that sentence in 2148 Code Case.