Do all these valves need to be closed completely during parking for maintenance? If the electric valve in the middle is turned off in the DCS, is it okay not to turn off the on-site front and rear control valves? It’s a low-pressure steam pipeline, with steam flowing continuously; today I saw something there at that flange again

If the unit is shut down, the steam in that section should have its electric valves and manual valves closed; in the case of a long-term shutdown, blind flanges must be installed to purge the pipelines thoroughly；

It’s just that formal production has not yet begun; the material feeding and trial runs are already complete. Some places are currently undergoing technological upgrades.

The valves in the valve assembly are provided for replacing or servicing electric valves; if a manual valve is leaking, the upstream valve can be closed to release the pressure in the pipeline, allowing for maintenance

For technical upgrades, it is necessary to purge certain pipelines thoroughly before proceeding with the work; the unit should still be powered by steam. It is recommended to close the electronic valve and the upstream and downstream manual valves, and to cut off the water supply before turning the unit back on

I agree with your view. A short pause doesn’t need to be turned off; for a longer period, it should be disconnected automatically. It is also necessary to take into account that different media and pressures require separate treatment in order to prevent pressure buildup between valves

Everything mentioned above is quite thorough; here are a few additional points: 1. You haven’t started actual production yet, and your steam pipelines require technical modifications. It’s necessary to relieve pressure in those pipelines and cool them down, as well as to perform blind plugging at the beginning of those pipelines. Additional note: In general, if a shutdown lasts more than three days, it’s required to cut off steam supply within the company. Prevent waste. If you are using steam from an external source, do the calculations to determine the required amount (the supplementary volume). 2. There are ways to shut off valves and install blind flanges: first close the front valve, and after pressure has been released, then deal with the rear valve, in order to avoid pressure buildup ； Also, regarding this dripping issue, you need to check whether it’s a problem with the choice of flange ； Or it could be a screw tightening issue. Whether it’s the blind seal or the valve condition, it is recommended that you ensure proper labeling on the tags. Facilitates employee handover and identification ；

1. Whether to turn it off depends mainly on the length of the parking time. If further technical modifications are required, not only must it be shut down, but the electric control valve also has to be removed before it is put back into use, followed by a purge process before it can be installed again ； 2. As for the leak issue at the flange you mentioned, it is definitely due to thermal expansion and contraction; the steam system needs to be tightened when it is shut down, and tightened with heat when it is put into operation. The above is for reference only!