Should the stop valve be removed during pipeline purging?

There is no need to remove it; simply opening the stop valve is sufficient, as gas is used for pipeline purging and the pressure is not high enough to damage the valve.

Do stop valves have a direction? I’m not entirely sure; I’ll try to find out. What about the check valve?

Keep the stop valve in the open position. Generally, there’s no big problem. If the purge pressure is too high, for safety reasons, you may consider removing the stop valve.

If there is a lot of slag in the pipeline, it’s possible for the slag to get stuck inside the valves during the purging process. Well, if there aren’t many valves, it’s fine to remove them.

It has a purge function; I wonder if it should also have a waste discharge device. By the way, since that stop valve is used in pipelines that require purging, does that have any impact on its diameter or structure? Thank you!

There’s no need to remove it; just open it

It should depend on the air pressure and the cleanliness of the pipeline, especially for soft-sealing materials

If there is concern about slag getting stuck, then aren’t gate valves also prone to getting stuck? The gate valve is not removed during blowing

When we perform purging, we only remove the check valve spool and the control valve...

After reading the above answers, I’m not very clear. The details are as follows: According to Chapter 8 of GB50235 \"Code for Construction and Acceptance of Industrial Metal Piping Projects\": \"Before pipeline cleaning, orifice plates, control valves connected by flanges, important valves, throttle valves, safety valves, instruments, etc., should not be installed. For the aforementioned valves and instruments that are welded, protective measures such as using bypass circuits or removing the valve heads and seats and covering them with protective sleeves should be taken.\" ” Therefore, I believe that for ordinary stop valves that are not considered “critical valves,” online purging is possible as long as safety can be ensured (for example, by keeping the valve fully open to ensure that the purging medium flows in the same direction as the valve’s installation direction).

Generally, during pipeline purging, the globe valve needs to be removed.

There’s no need to remove it; it can be opened directly. That control valve is used in pipelines where purging is required – so does that have any impact on its diameter or structure?

There’s no need to remove it! Just blow in the direction of flow of the stop valve! Generally, the purging pressure will not be higher than the operating pressure of the stop valve!

It must be removed; otherwise, the valve seat seal will be damaged during blowing, leading to internal leakage of the valve in the future.

“\"Damaged valve head sealing surface\" – is this expression used for other types of valves as well?

There’s no need to disassemble them; we just made a few such valves a few days ago

We don’t disassemble it here, but the medium is usually steam, and it does not belong to chemical hazardous materials.

8.1.4 Before pipeline purging, orifice plates, flanged control valves, important valves, throttle valves, safety valves, instruments, etc. should not be installed. For the welded valves and instruments mentioned above, protective measures such as using bypass circuits or removing the valve heads and seats and covering them with protective sleeves should be taken. 8.1.5 The purging sequence shall be in the order of main pipes, branch pipes, and drainage pipes; the dirt removed during purging must not enter the pipes that have already passed inspection. 8.1.6 Before purging, the stability of pipe supports and hangers should be checked, and reinforcement should be carried out if necessary. GB50235-1997 Code for Construction and Acceptance of Industrial Metal Piping

The stop valve does not need to be removed, but the check valve must be removed and installed in reverse when purging in the opposite direction!