Blind Flange vs. Reducing Flange in B16.5

[Texas Piper]

I would like some help clarifying what is allowed and what is not regarding B16.5 and selection of blind flange vs reducing flange.

Due to a combination of events and space constraints, we have a 4" NPS nozzle on a tank that needs to immediately reduce down to a 2" NPS.

If I am understanding B16.5 table 6 correctly, this connection must use a 4"x2" reducing flange, and not a blind flange with a penetration.

A blind flange with penetration would be allowed in this circumstance if the pipe was a 1 1/2" NPS or SMALLER. Table 6 specifies this based on a threaded tap on the blind flange, but this will not be a threaded connection...

Am I correct here or do I need to go apologize?

 

[1503-44]

I haven't tried, but I doubt there will be very much metal left in a 4" blind after you drill and tap a 1.5 into it.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[XL83NL]

Texas Piper. Acc. table 6, you require a high hub flange for NPS 1.1/2” and greater.

This doesn’t per se apply to threaded flanges. The examples provided are for threaded flanges, but the table may also be used for for example slip ons or blinds in which a pipe is welded.

We typically buy the high hub flanges without a bore (i.e. ‘massive’) so we can go all directions we like

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

 

[r6155]

You can weld a reduction NPS 4 x 2 and then a flange NPS 2.

Regards

 

[LittleInch]

Yes you are correct.

note min thickness of a 2" SO flange is 24mm

Min thickness of a 4" blind flange is 22.3mm

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

 

[Texas Piper]

Thanks for the replies.

@LittleInch and @XL83NL thank you for the confirmation.