Half Coupling Note in Mechanical Drawing
Half Coupling Note in Mechanical Drawing
(OP)
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In an NPT half coupling, one of the diameter of the coupling is larger than the other side.
In my project, the half coupling must be welded in the proper direction.
How do I address this in a mechanical drawing?
In other words, what note should I write in the drawing to show that the larger diameter of the hole has to be in the bottom and the smaller one has to be in the top and not the other way?
Thank you,
vh
In an NPT half coupling, one of the diameter of the coupling is larger than the other side.
In my project, the half coupling must be welded in the proper direction.
How do I address this in a mechanical drawing?
In other words, what note should I write in the drawing to show that the larger diameter of the hole has to be in the bottom and the smaller one has to be in the top and not the other way?
Thank you,
vh





RE: Half Coupling Note in Mechanical Drawing
You shouldn't need a note unless you're doing something completely counter-intuitive to an experienced fabricator, e.g. welding the half-coupling to the bottom surface of a tank in such a way that a nipple can be screwed into it from inside the tank, e.g. to make a standpipe.
Mike Halloran
Pembroke Pines, FL, USA
RE: Half Coupling Note in Mechanical Drawing
RE: Half Coupling Note in Mechanical Drawing
Exaggerated taper is a good idea. I also increased the scale to make it look more clear.
RE: Half Coupling Note in Mechanical Drawing
Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services
www.infotechpr.net
RE: Half Coupling Note in Mechanical Drawing
If your really worried about it, maybe go as so far to note
"NPT ADAPTOR ORIENTATION CRITICAL" as well in the prints note section. It's your print/contract to get your point across, there isn't a symbol for everything.
RE: Half Coupling Note in Mechanical Drawing
Mike Halloran
Pembroke Pines, FL, USA
RE: Half Coupling Note in Mechanical Drawing
But I have to agree with Mike. Anyone running a shop welding half couplings on who can't figger out which end the pipe goes in to... Well, they won't be getting a lot of repeat business.
jt
RE: Half Coupling Note in Mechanical Drawing
RE: Half Coupling Note in Mechanical Drawing
jt
RE: Half Coupling Note in Mechanical Drawing
RE: Half Coupling Note in Mechanical Drawing
I'm guessing they were done that way by an experienced fabricator as some sort of 'malicious obedience'.
Mike Halloran
Pembroke Pines, FL, USA
RE: Half Coupling Note in Mechanical Drawing
RE: Half Coupling Note in Mechanical Drawing
Thanks.
R.
RE: Half Coupling Note in Mechanical Drawing
A few notes, aligned with the comments above. * A junior welder on the job for his first day would not be allowed to touch alloy piping. This stuff looks like some flavor of stainless or higher.
* Fitup looks good.
* Weld quality looks ok.
* Even an apprentice welder would (should?) have seen a flange pair before and would be expected to have an understanding of the mechanical assembly of flanges.
Thus, it is my opinion that this was the job of a senior welder within a week of retirement or quitting. Perhaps in a response to a junior engineer telling him exactly how to weld the flanges to the pipe. As per Mike's eloquent phrase above, 'malicious obedience.'
jt