Dear experts, please help

20 drain valve, ball valve, with pipe cap

It’s obvious, right? The ball valve for the drain line

This post was last edited by Vast seas and boundless skies_HVEY on 2019-10-9 at 18:20. Generally, there is a separate legend diagram at the beginning of a PID diagram, from which information can be obtained directly. But from the picture you provided, I think this valve is a globe valve, as gate valves are identified with a Z at the beginning of their codes, while this valve’s code starts with J; hence this inference. The second reason is that, according to some design institutes, the circle in the middle of a ball valve is not solid, whereas for globe valves, some design institutes represent it as being solidly filled. In China, gate valves are probably used more often as drain valves, but in a foreign project I was involved in, all the drain valves were stop valves. It’s possible that foreigners think that globe valves can provide a better control over the slow release of the medium and pressure within the pipeline, thereby preventing the medium from bursting out suddenly and causing injury; I hope this helps you

Discharge valve, sampling valve. According to PSM requirements, a plug or dual valve must be added at the end