Nozzles on a blind flange
Nozzles on a blind flange
(OP)
I am adding (3) 1-1/2 nozzles to a 20" 300# manway cover for use as termowell connections.
My nozzles meet the requirements of UG-36(c)(3)for not needing re-inforcement. When I do an appendix 2 calculation for the flange thickness, the required thickness is greater than the 2-9/16" thickness of a standard 20" 300# blind.
My question is: Since I am altering the manway cover by adding the nozzles, am I now required to satisfy the requirements of Appendix 2. This will require me to use a flange that is thicker than standard.
Any advice is greatly appreciated.
My nozzles meet the requirements of UG-36(c)(3)for not needing re-inforcement. When I do an appendix 2 calculation for the flange thickness, the required thickness is greater than the 2-9/16" thickness of a standard 20" 300# blind.
My question is: Since I am altering the manway cover by adding the nozzles, am I now required to satisfy the requirements of Appendix 2. This will require me to use a flange that is thicker than standard.
Any advice is greatly appreciated.





RE: Nozzles on a blind flange
RE: Nozzles on a blind flange
If you had a single, central opening, your situation would be relatively easy as vesselfab has indicated. See Table 6 in B16.5 2009 (page 70) or Table F6 in the 2003 ed (page 162). The table could be written more clearly, but in your case it shows that a 20" blind only needs reinforcement (hub) if it is used as a reducing flange for a 4" NPS connection or larger (columns 5 and 6). For outlet sizes smaller than NPS 4 no reinforcement is required and the flange with a hole drilled for a 1.5" connection does not change the blind's conformance to B16.5. Thus, as far as Section VIII-1 is concerned, no calc's required for the blind and its opening since it conforms to B16.5. The nozzle neck itself and beyond will require the usual VIII-1 calc's unless you consider what is beyond the blind to be piping.
However, for multiple openings or a single off-center opening, yes, you need to conform to VIII-1 rules since the blind is no longer in conformance with B16.5.
jt
RE: Nozzles on a blind flange
But in principle there would seem to be no restriction against attaching the "custom" UG-34 bolted cover to a "standard" B16.5 weld neck (etc) flange. This method would prevent the often-encountered problem that many B16.5 flanges do not meet their standard pressure-temperature ratings when analyzed per Appendix 2.
RE: Nozzles on a blind flange
I did not see that (3) in front of the nozzle size
Sorry for any confusion I may have caused
RE: Nozzles on a blind flange
Could you please clarify whether Table F6 is only for threaded connection OR we can apply this to welded connections as well.
Regards,
Starrproe
RE: Nozzles on a blind flange
jt
RE: Nozzles on a blind flange
jt
RE: Nozzles on a blind flange
I have come across a case where I need to provide a 16" opening in blind flange of 24" manway.(I can't use a 24x16 concentric reducer due to process constraints.)
I am planning to go for a 24x16 reducing type slip-on flange.Of course, the reducing outlet would need a hub as specified in Table 6 of B16.5.
Will this type of reducing flange conform to B16.5 requirements?
Have you ever used such a configuration?
Regards,
Starrproe
RE: Nozzles on a blind flange
My first instinct when I saw your other post was to suggest a reducing elbow. Not the cheapest piping component, but avoids a weld and might be a bit more compact.
Sounds to me like you are saying you will order a flange which complies with B16.5. If so, well, then it conforms to B16.5. What am I missing here?
I don't recall using such a configuration. I'd go the reducer or reducing elbow approach with these diameters.
jt
RE: Nozzles on a blind flange
Thanks for your response...
I am sorry if my statement has caused you some confusion, but actually I wanted to know whether I can have any size of reducing slip-on flange,especially with openings greater than those allowed per Columns 2,4 & 6 of Table F6 (e.g. NPS 24 x 16).
Will such a flange still be conforming to ASME B16.5, provided the dimensional requirements of Table F6 and 6.8.2.1(for hub)are met.
Regards,
Starrproe
RE: Nozzles on a blind flange
Yes.
jt