Hole in a Blind B16.5 smaller than 1"

[CrisDom]

Does anybbody know what to do in case I have a drilled blind smaller than 1"?
ASME B16.5 Table 6 starts from NPS 1.
I'm afraid I've to calculate blind smaller than 1" as non std in case I have to drill it with a central hole...

Thanks

 

[LittleInch]

Insert a 1" adaptor down to what ever size you need?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[CrisDom]

LittleInch, unfortunately I'm not in a position of adopting a different solution, since I've to design a vessel with a 1/2" nozzle, a 1/2" WN flange and a 1/2" blind with a threaded hole 1/2" NPT.
I suggested to my client to use a threaded flange instead, but, for this particular case, he is forced to maintaint this configuration.
So I was wondering whether ASME Code (or any other ASME std such as B16.5) provides a way to use drilled std blind without the need of calculating it (being Table 6 of ASME B16.5 a valid solution for NPS > 1).

Thanks

 

[XL83NL]

Afaik, no, not in the Codes

Huub
- You never get what you expect, you only get what you inspect.

 

[SnTMan]

CrisDom, what is your vessel Code? For example Sec VIII, Div 1 provides rules for openings in flat heads. You may have to (heavens!) perform a calculation.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[CrisDom]

Mike, I'm in ASME VIII Div.1 and I know there are rules for openings in flat head.
I don't have difficulties in calculating blind and its opening; as you can imagine, the problem is not the opening, but the blind itself, since the calculated thk in seating condition is quite higher than the installed one.
Sometimes, for small and simple vessels (like "mine"), it's difficult to make manufacturer understand the need of changing such little components because of Code rules and so on, so I'm doing my best to convince him to change the configuration (e.g. using a threaded coupling directly welded to the vessel wall, instead of a pipe+WN+Blind+threaded hole!!).
Except my efforts with manufacturer, I was just curious about the possibility to avoid the calculation (simply to learn something that I don't know).

Thanks for your feedback.

Regards

Cristiana

 

[SnTMan]

...since the calculated thk in seating condition is quite higher than the installed one.

Oh. You had done calculations. Was not obvious. Does not appear to me that the opening can be exempted per UG-39(a), so looks like a custom flat head or change of configuration.

It does kind of surprise me that your blind does not meet UG-34 for seating. Anyway, best of luck.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[LittleInch]

My apologies, OI read this as being a 1/2" hole in a blind, not a 1/2 " blind....

But what exactly is the difference between a 1/2" blind flange with a 1/2" tapping and a 1/2" screwed flange??

They look virtually identical to me.

Or get a socket welded flange and weld on a threaded stub?

I'm not seeing what the issue is here to some alternative.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[SnTMan]

I think the difference is the hub. But, yes, exactly, why not use a 1/2" screwed flange?

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[moltenmetal]

If you have a 1/2" WN and need a 1/2" NPT coming out, you don't need a drilled blind- you need a 1/2" threaded flange. That flange will have a hub. Yes, they exist, at all flange classes- even ones where a threaded joint would be troublesome.