For economic reasons, is it possible to change the diameter before and after switching the valves?
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An electric on/off valve (ball valve) should be used on the pipeline. According to the standards, a pipe of size 100 is required, but electric control valves of size 100 are much more expensive than those of size 80. My question is: can we use valves of size 80 and then install a reduction fitting of 100*80 before and after the valve?
In general, it is not allowed to change the valve specifications, as this will affect the flow pattern of the fluid and cause unstable operation; moreover, sudden contractions or expansions will increase resistance. If production is urgent and no valve of the appropriate specification is available, a temporary one can be used until a valve with the right specifications arrives and can be replaced.
Sure! As long as the pressure drop across this pipeline allows it. Many companies abroad choose smaller automatic valves for their pipelines.
I agree with what was said above; in fact, I have encountered it as well. That’s how the company’s natural gas pressure regulation stations are structured: the pipes have a diameter of Φ133, and DN100 valves are used for them; whereas for pipes with a diameter of Φ109, DN80 valves are utilized. If used in pipelines, it will increase pipeline resistance (there is an additional resistance due to the diameter changes; the resistance when the ball valve is fully open is almost zero)
The diameter changes little, and the resistance is not high when it is fully open. :lol :lol :lol
The fluid erosion at the diameter-changing section is severe, which can easily thin the pipe wall and poses safety risks