How is the height of the connection fitting for temperature instruments installed on flanges generally determined?
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Regarding the installation of temperature instruments, the most commonly used guide in design is the installation manual from the chemical industry standard HG/T21581. This manual provides reference heights for the straight-type connectors used for threaded installation of temperature instruments, such as H=60 or H=120. However, no numerical values are provided for the flange connections (as shown in the diagram). Our pipeline specialists are not very clear on this either. My personal opinion is that it’s sufficient as long as the height is slightly higher than that of the pipe’s insulation layer, but I can’t find any reference for this. Dear experts, how do you generally determine the height of such flange connectors? How much should the value be? Thank you!
It is usually 200 mm, to be determined through consultation between the process engineers
Provide data for a certain Class A plant: L is the length between the flange sealing surface and the outer surface of the pipe. For CL 150, L=150; for values above that, L=230. This is specified in the \"Pipe Installation Guidelines\".
Increase the thickness of the insulation layer by 100 mm; otherwise, it will be difficult to tighten the screws
80-150, depending on how deep your device is inserted. It’s too long; the insertion depth is insufficient
If it’s a temperature sensor on the equipment, it has nothing to do with you. But if it’s a temperature measurement point on a pipe, the instrument itself will have specific requirements. Generally, it’s necessary for the sensor to extend into the pipe. Since different project owners have varying requirements regarding thermometers, it’s usually the instrument manufacturer who specifies whether a pipe needs to be resized (from smaller to larger). If you’re not sure, ask the instrument specialist; they will explain it to you clearly. Be humble and polite, and they’ll generally provide a thorough explanation
This is something that has been established by convention; otherwise, how could thermocouples (resistors) be designed?
Refer to the table in HG/T21581 1995 – you’ll be able to see right away that the flange is of 150 class, and the length of the protective sleeve corresponding to that pipe diameter is also indicated there. Ask if there’s anything you don’t understand.