Nozzles on a blind flange 3

[MalcolmA]

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.

 

[vesselfab]

use a reducing flange and forget it

 

[jte]

Malcolm-

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

 

[TomBarsh]

Some confusion here: The bolted cover is designed per UG-34, the adjoining flange has likely been analyzed by Appendix 2.

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.

 

[vesselfab]

GEE

I did not see that (3) in front of the nozzle size

Sorry for any confusion I may have caused

 

[starrproe]

jte,

Could you please clarify whether Table F6 is only for threaded connection OR we can apply this to welded connections as well.


Regards,
Starrproe

 

[jte]

The table clearly shows slip on welded flanges...

jt

 

[jte]

If you have a socket weld, that’s also included:

6.8.2.1 Threaded, Socket Weld, and Slip-On Flanges. The hub dimension shall be at least as large as those of the standard flange of the size to which the reduction is being made. The hub may be larger or omitted as detailed in Table 6 (Table II-6 of Mandatory Appendix II).

jt

 

[starrproe]

jte,

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

 

[jte]

Process constraints? The flow through a reducer will be much smoother than that through a reducing flange. Or is there some other concern?

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

 

[starrproe]

jte,

Thanks for your response...

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 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

 

[jte]

Starrproe-

Yes.

jt