Selection of the root valve for pressure gauges
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When I first started working on design, pressure gauges always required stop valves, and that’s what others did as well. As I came into contact with more projects, I noticed that foreigners often choose ball valves for LNG applications. I understand that globe valves have a throttling effect, which may make it difficult to reflect the actual pressure Later, I saw that a domestic engineering company adopted a approach in which a flow-limiting element was added and then a ball valve was connected, which gave it the same function as a globe valve. They must have a reason for doing this; it’s just hard to figure out what it is. I was wondering if any of you sea friends could offer some guidance.
Personally, I think ball valves are used in LNG projects because of their good sealing properties, as well as the fact that they can handle higher pressures. The choice should primarily be based on the characteristics of the medium and its pressure levels; ball valves are clearly not suitable for applications involving high-temperature steam. So, I believe it mainly depends on the operating conditions
Although a globe valve has a throttling effect, it does not affect the pressure gauge’s ability to reflect the true pressure, as the pipe section between the globe valve and the pressure gauge can be considered virtually flow-free (there is some flow, but only in small amounts); it represents a relative \"dead zone\".
Our company uses both globe valves and stop valves, with a greater number of stop valves and fewer globe valves; it is estimated that economic considerations are the main determining factor.
The explanation on the 3rd floor is correct~~Throttling does not affect pressure~~If the pressure is high and the flow rate is too fast, it can easily damage the pressure gauge; therefore, pressure gauges are usually equipped with stop valves, and there is a bend between the valve and the gauge, which also serves to protect the pressure gauge.
I agree with what was said on the 4th floor. Our company can use both ball valves and globe valves for these purposes, but due to cost considerations, globe valves are chosen more often. Ball valves offer better sealing performance and can handle higher pressures; in my opinion, either type is suitable
Bro, why are globe valves cheaper than stop valves? ?
Valves in the boiler system: globe valve + pressure gauge elbow + tee valve + pressure gauge. Sometimes there is more than one stop valve; it’s possible to have multiple of them.
Generally, for ball valves and gate valves with identical specifications (equal PN and DN values, and basically the same casting material), ball valves have a higher cost. The main reason for this is that the valve core of ball valves is more difficult to manufacture.
Pressure gauge elbows are generally connected to tee valves; in my opinion, the way foreigners do it doesn’t have any special meaning
We use globe valves for the root valves of our pressure gauges