Please tell me about the choice of plug, threaded pipe cap and flange for the outlet of the purge valve?

It's a good question, but no one has answered it.

I also want to know, but I never quite understand. It’s just that the master said before that when drawing a PID, you only need to leave a piece of flange for purging on the equipment, and use a pipe cap for purging on the pipeline. Looking forward to the expert's answer. . .

During the design process, there is generally not much difference between the plug and the threaded pipe cap for the outlet of the purge valve, and they can basically be used interchangeably. However, for materials that are prone to clogging in the process, highly corrosive materials, and places where the pipes are made of carbon steel and are not discharged frequently, blind flanges should generally be used. :)

There is no difference in the application of plugging and pipe caps! ! ! All to prevent leaks! If the place is basically not open, a blind flange must be installed to prevent leakage! If the discharge needs to be operated frequently, use a pipe cap or plug. However, the strength of the plug is higher, and the cap is sometimes of poor quality and easily broken.

From the factory operation point of view, only a short length of pipe is needed, there is no need to make it so complicated.

Their functions are similar. They are all used to prevent leakage and pipe blockage. I have never used pipe caps. They are mainly used in safe and harmless media and places that need to be discharged frequently to facilitate operation. For dangerous, high-pressure media or places where operations are infrequent, it is best to use blind flanges.

1. Pipe plugging is generally only used for high-point venting during hydraulic testing of pipelines. After the pressure test is completed, it can be sealed by electric welding.； 2. Other functions are to prevent material leakage, oxygen in the air and corrosive gases in the factory from corroding the purge valve and affecting the opening and closing of the valve. ； 3. Pipe caps and plugs are mostly used for pipes with low temperature and pressure and almost no danger or corrosiveness. ； 4. Flanges are mostly used for pipelines with high temperature and pressure, high toxicity, and high corrosivity. In addition, flanges are also required for pipelines that require heat treatment such as liquid ammonia.

1. Pipe plugging is generally only used for high-point venting during hydraulic testing of pipelines. After the pressure test is completed, it can be sealed by electric welding.； 2. Other functions are to prevent material leakage, oxygen in the air and corrosive gases in the factory from corroding the purge valve and affecting the opening and closing of the valve. ； 3. Pipe caps and plugs are mostly used for pipes with low temperature and pressure and almost no danger or corrosiveness. ； 4. Flanges are mostly used for pipelines with high temperature and pressure, high toxicity, and high corrosivity. In addition, flanges are also required for pipelines that require heat treatment such as liquid ammonia.

I would like to ask, is it a mandatory standard requirement to add a blind plate or plug after the discharge valve (sampling valve)? Which standard? We got fined for this, the ammonia pipeline

It is generally recommended to use blind flanges for high pressure and hazardous media. Your medium is ammonia, so blind flanges should be used. Wire plugs are used in low pressure, non-hazardous media. Because the plug is more likely to leak than the blind flange, the blind flange is the safest!

Thank you for your reply upstairs, but I feel that the risk increases after adding a plug or flange, because the valve may leak internally, but the operator cannot detect it in time. When the plug or blind plate is opened, the medium inside will spray out and hurt people.

vent end: Pipe caps and plugs can be used in any industrial and mining pipelines with low or high temperature and pressure, non-hazardous, hazardous or corrosive conditions. When venting at the high point of pressure test, the pipe will be sealed and welded after the pressure test. Flanges are also available at the process vent ends. There is no need to add a valve for venting for pressure testing, but a valve is required for venting for process purposes. Drain the ends: Pipe caps and plugs are used in low-pressure, low-corrosion industrial and mining processes, while flanges are mostly used in pipelines with higher temperature and pressure, higher toxicity, and higher corrosiveness. Drainage generally requires adding a valve, and double valves are required for highly toxic fluids. For details, see Professor Yue Jincai's "Pressure Pipeline Technology" and Professor Song Keke's "Pressure Pipeline Design and Engineering Examples".

Relatively speaking, flanges are more expensive than plugs or caps.

I was reading this question just now, and I understand it a bit. I’ll check it out again.

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