For a magnetic flap level gauge, what is an appropriate length for the short section to use?
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As shown in the diagram, it is required that a short section be installed between the equipment and the ball valve when installing the level gauge. However, considering the use of bolts, it is necessary to specify the length of this short section; what is an appropriate value for this length?
As long as there is a connection, no matter how long it is, it will not affect the measurement
The purpose of shortening the section is to lengthen the pipe connector; according to your requirements, there are no restrictions, so we will manufacture the equipment. Some customers request an insulation layer, and in such cases the pipe connector is lengthened as specified in the drawings.
In your diagram, the short section is placed between the valve and the equipment; it would be better to place it on the other side of the valve…
There are no strict requirements regarding this length; it can be determined based on ease of use.
The leader said that this section was added due to regulatory requirements, but it’s the first time I’ve heard of it, and I couldn’t find any relevant regulations
I haven’t heard of any regulatory requirements; it’s sufficient as long as the pressure rating meets the specifications and the installation is possible. There are many such cases on site, where the design of the equipment and platforms doesn’t take into account the implications of installing instruments there.
It’s restricted by welding, I guess; it’s too short – the flange and the short pipe can’t be welded together. It should work fine if the length is above a certain threshold.
Try to avoid adding short sections; instead, add more short sections to increase the leakage points. All couplings generally take into account bolt installation, and one only needs to choose the appropriate bolts. Generally, the use of a short coupling is necessary because the dimensions of the pipe fitting and those of the magnetic flap differ, requiring an adapter.
There are two possibilities for using a short coupling: one is that the standards of the equipment flange and the instrument flange differ, requiring a short coupling to convert the flange standards； Secondly, the insulation on the equipment might be quite thick, requiring the use of short sections to expose the valve. There are no specified requirements regarding the length of the short sections; however, the code does set requirements for the spacing between the two welds (that is, the welds at both ends of the short pipe), as stated in clause 7.2.6 of GB50236.