What type of valve is used for the valve at the root of the pressure tapping point?
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My previous factory has always used needle valves; now I see that some places are using plug-welded gate valves. I feel that such valves are a bit more difficult to maintain, not as convenient as needle valves. Please share your opinions on the characteristics of these two types of valves
The poster is referring to conical and needle-shaped, right?
We are using external-threaded stop valves
I don’t think there’s anything special about it; its function is simply to separate the container from the pressure gauge, as long as it achieves that purpose. However, if welding is used, it is more troublesome to replace the valve once it is damaged.
Actually, there isn’t much difference. Needle valves are widely used, are easy to purchase, and also have good pressure resistance and sealing properties
It is probably mainly to reduce the number of sealing points; it is related to the process conditions of the device, especially in cases where there are toxic or harmful substances involved. In thermal systems, socket welding is often used for the root valves at various sampling points, as it provides better pressure resistance.
It is advisable to use a needle valve as the root valve at the pressure tapping point.
Ball valves or globe valves are more suitable for use as root valves, as they are easier to maintain and result in less leakage. Pin valves are not very suitable; although they have low leakage, they tend to clog easily. I think a globe valve with a sleeve connection is the best choice.
In previous design institutes, flanged gate valves were used quite frequently; nowadays, in design institutes, socket-welded gate valves are used for pipelines, while flanged gate valves are used for equipment. Owners generally do not prefer ball valves, as they tend to get clogged, and if such valves are used, the owners will request that gate valves be used instead.
Pin valves tend to get clogged; gate valves are the better choice.
Ball valves, globe valves, and needle valves that are fitted by socket welding or threading are all suitable; the choice is mainly determined by factors such as the medium, pressure rating, and operating temperature
Pin-type valves are not very suitable; although they have low leakage, they tend to clog easily. It is recommended to use socket-welded or threaded ball valves, globe valves, and gate valves.
Plug-and-socket welded gate valve, pressure-resistant with good weld sealing
Plug-welded gate valves, globe valves, and needle valves are all suitable; the choice is mainly determined by factors such as the medium, pressure rating, and operating temperature
Welded stop valves are better, but care must be taken to protect the threads and handle during installation; otherwise it can cause a lot of trouble if they get damaged.
It is best to use gate valves; needle valves are too prone to clogging.
For projects that are not at ultra-high pressure, we generally use needle valves; for ultra-high pressure projects, and when required by the design institute, we use welded globe valves + dual-valve assemblies, or integrated flanged welded globe valves + flanged dual-valve assembly globe valves.
It is recommended to use gate valves or ball valves; needle valves are too fragile and prone to leakage, while socket-welded gate valves or ball valves will definitely be very durable.
The one-way valve must be a socket-welded globe valve. Safe and reliable. But after socket welding, there must still be a threaded needle valve or something similar. Easy to maintain.