Questions regarding the instrument installation diagram
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In HG/T21581-2012, the manual for automatic control installation, regarding the socket weld connection method used for measuring liquid flow rates, the pressure transfer pipe is connected to the valve assembly; is the end of the pipe equipped with a butt-welded straight threaded fitting, or does it have external threads? From what I remember, in the factories I’ve been to, the pipe ends use internal threaded connectors, similar to those used for connecting to pressure gauges. Is this also the case here, according to the experts on this forum?
Since this five-valve assembly has internal threads, external threads should be used for the connections
I remember that on-site, a straight-through piece with an external thread was added to the internal thread of the five-valve assembly, connecting to the threaded end fitting of the pressure pipe
If the end of the pressure tap is not a swivel, how can it be screwed on?
The five-valve assembly has internal threads; the pressure connection pipes must have external threads, as is clearly shown in this diagram
I understand this; the key is the external thread on the pressure Intake pipe Is it easy to install this gauge? The tube is fixed, so you have to rotate the gauge, which is really annoying to watch
Maybe the design wasn’t thought through in enough detail; would using union Yuin joints be better? Or tubing fittings.
Design doesn’t care how you try to manipulate it; in fact, all the units with five valve assemblies in our company are like this
If it is designed to look like a pressure gauge, with a pressure gauge connector welded at the end, the design should take everything into account, right? I wonder what the underlying rationale for the design in the catalog is
Is it all designed this way? Was that’s how the work was carried out on site during the briefing?
The starting point is unknown. I guess it’s the No. 4 NPT external thread, which facilitates protection – just wrap it with tape or cover it with a cap to prevent dirt from getting in ； Damage to the external thread compared to the internal thread can be seen clearly, making it easier to replace it or to re-tap the threads.