Sect. VIII Div. 1 - Nozzle radius requirements? 4

[Christine74]

Is there any requirement in ASME Section VIII, Div. 1 for rounding off nozzle IDs at the nozzle/shell intersection? If so, would this requirement apply to nozzles with an internal projection?

I've noticed that many manufacturers show a 1/8" radius on their nozzle details, but I'm not finding it in the code. Why is this needed?

Thanks,

-Christine

 

[doct9960]

Christine,

Is there any requirement in ASME Section VIII, Div. 1 for rounding off nozzle IDs at the nozzle/shell intersection? If so, would this requirement apply to nozzles with an internal projection?

Yes, see UG-76(c)

I've noticed that many manufacturers show a 1/8" radius on their nozzle details, but I'm not finding it in the code. Why is this needed?

To reduce stress concentrations and for safety (less injury from cuts in case you bump into one).

Cheers!

 

[SnTMan]

Huh, learn something every day...

 

[vesselfab]

we radius every corner on every part. Just for general principal. On internal projections and internal parts as stated earlier. All external clips so paint will stick to corners.

 

[doct9960]

Christine,

I found an ASME interpretation on UG-76(c). Here's an excerpt from Interpretation VIII-1-83-211...

Question (2):
(a) When nozzle necks extend inside the vessel shell beyond the limits of reinforcement, are the exposed edges required to be rounded or chamfered as per UG-76(c) of Section VIII, Division 1?
(b) Do the above requirements of UG-76(c), within the limits given above, apply to pipe, forgings, and/or plate necks?
(c) Do the requirements of UG-76(c) apply to the exposed shell edge for openings as shown in Fig. UW-16.1 sketch (bb) and Fig. UW-16.2 sketch (p)

Reply (2)
(a) Yes.
(b) Yes.
(c) Yes.

 

[SnTMan]

Very, very common practice, I just didn't know it was Code.

Thanks,

Mike

 

[jamesl]

I have to disagree with doct9960. You do need to remove all exposed sharp edges (not just on nozzle corners), however 1/8" radius is not required by code.

I remember that the code added minimum nozzle corner radius requirement (1/16 chamfer or 1/8” radius) in Para. UW-16(a)(3) in 97 Addenda, and deleted the whole paragraph after receiving a lot of objection from users. Now the radius is only required when called out in UW-16.1 sketches. 1/8” corner radius is no longer a code requirement. To meet UG-76(c), you could put any size of chamfer or radius. There are no minimum requirements in UG-76(c).

I do agree the 1/8” radius is a common practice in many vessel shop.

 

[jte]

Further, my understanding is that the larger radius requirements in Div. 2 are going to disappear and be limited to the 1/8" callout for some Div. 1 designs as discussed above.

jt

 

[roca]

Client specs rule in the end and most of them require a corner radius on nozzles