How is the connection diameter of instruments on equipment determined?
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Hello everyone, I have to trouble you all again! I would like to ask everyone: what is the diameter of the connection holes on the instrumentation for equipment pipelines? Do temperature instruments, pressure instruments, level instruments, flow meters, and analysis instruments all have their own specific connection hole sizes? I wonder whether the size of these holes varies depending on the type of instrument What are the typical opening connection dimensions for various instruments?
This is generally determined based on the pipe diameter specified by the instrumentation specialists, with values typically ranging from 3/4 inch to 1.5 inches.
Determined based on the interface dimensions provided by the instrument manufacturer
Aren’t there special pressure tapping stubs and bosses for that?
After selecting the appropriate instruments for the design, the connection type of flange or thread is determined. Thermometers, pressure gauges, pressure transmitters, etc. can be connected using flanges or threads ； Most of the other instruments are flanged. The flange size is generally DN25 to DN80, with threads of M20*1.5 or M27*2 or G1/2 to 3/4 or 1/2NPT, etc.
I’ve learned it, but what I also want to ask is whether there is a **standard** for this. For example, as mentioned on the 5th floor, after selecting the appropriate instruments for use, it is determined whether flange or threaded connections will be used. Thermometers, pressure gauges, pressure transmitters, etc. can be connected using flanges or threads ； Most of the other instruments are flanged. The flange size is generally DN25 to DN80, with threads of M20*1.5 or M27*2 or G1/2 to 3/4 or 1/2NPT, etc. Are there any regulations and standards for these? Please advise
When designing equipment, designers generally consult the opinions of those specializing in automatic control. This way, the process connections for the instruments chosen can be provided to the equipment design team in advance, and they will design the equipment according to those specified pipe connections. If the equipment is already available, the connection method and size of the instruments are determined based on the ports on that equipment. Nowadays, instrument manufacturers generally meet users’ requirements; if that’s not possible, bypass connections can be used for conversion.
Of course, there are standards, such as SH-T 3104-2000, the Code for Installation and Design of Petrochemical Instruments. Generally, after all the requirements regarding the openings of instruments have been specified in the unified design regulations, then the selection of instruments takes place.