Welding a welding neck on a blind flange

[Julianbarrera]

Hi,

In a pressure vessel of 75 psig of design pressure there´s a 20" manhole, for the rigth operation of the equipment it needs a vent nozzle on this manhole, usually we made it by welding a 1" threaded coupling to the blind, but due to the rules our custommer is using, they don't allow this kind of fitting, so my idea is to weld a 2" WN flange to the blind, but don't know if it is allowed per codes. I'll appreciate any help. Thanks in advanced.

Julian Barrera

 

[XL83NL]

Allowed by codes -> which code? ASME VIII-1?
Regardless if allowed by the code (I think you wont find any section in ASME VIII-1 prohibiting welding a WNRF to BLRF), I wouldnt do it. Whats the extra cost of a small piece of pipe between the WNRF and BLRF, vs all the discussions, questions etc youll get for such an awkward arrangment?

 

[LittleInch]

Whats the 20" manhole and blind flange designed to? ASME VIII or ASME B 16.5

Is the hole central?

ASME B 16.5 allows you to tap a hole in the centre up to certain sizes.

Welding one on??

Doesn't talk about that.

I would thread on a piece of pipe then weld your flange if it's a B16.5 blind flange

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