Purge interface issue

According to Article 7.2.7 of GB-50160-2008 \"Code for Fire Protection Design of Petrochemical Enterprises\", when public service pipelines are connected to pipelines or equipment containing combustible gases, liquefied hydrocarbons, and combustible liquids, the following requirements shall be met: 1) Check valves shall be installed on publicly used pipelines that are in continuous operation, with isolation valves placed at their bases； 2) Check valves and one isolation valve, or two isolation valves, should be installed on the utility pipes that are used intermittently, with a test valve placed between the two isolation valves ； 3) Utility pipes used only when the equipment is shut down should be equipped with blind flanges or disconnected

Generally, check valves are used in conjunction with gate valves or globe valves. When selecting a check valve, it is taken into account the possibility of process materials flowing back into the purge gas line; as for gate valves or globe valves, the choice depends on the properties of the materials and the required sealing performance.

Logically, purging is meant to be used when the third piece of equipment is shut down; in such cases, a blind flange should be installed or the connection should be disconnected. However, in the PID diagrams I’ve seen, the most common setup is two valves along with quick connectors, while occasionally there are single valves equipped with plug seals or flange covers. Could it be that I’m not looking at the proper interface? . Fear. . But on the outlet side of the pump, the outlet side of the tank, and other such places, if it’s not a purge port, then what is it?

I learned that there are reservations available, but I didn’t know there were so many different types!

What I’ve encountered is that plug caps are generally used at the purging ports

Towers generally consist of valve assemblies with blind plates, while containers and pumps each have a single valve along with a blind plate

The provisions in GB50160 regarding the installation of valves at the junctions between utility pipes and process pipes are requirements formulated for situations where fixed connections are already in use. According to clause 2.0.3.3 of the specification HGT20570.18 \"Valve Installation,\" utility material pipelines should, as much as possible, not be fixedly connected to process material pipelines; instead, they should be connected using flexible hoses and quick connectors. When the operation requires a direct fixed connection, a dual-valve connection should be used, with a check valve installed in between. This check valve opens when feeding is stopped, or it can be sealed with a lead seal (C.S.O.). In situations where pressure may fluctuate, an additional check valve should be installed. ”If the pressure gauge for the common fluid is located far from this valve assembly, a pressure gauge can be installed between them to allow for on-site monitoring of the pressure of that common fluid during use. For safety reasons, the conservative approach nowadays is to combine the two standards, as well as to take into account both intermittent operation conditions and periods when the equipment is not in use. This involves installing a double valve setup along with a check valve and a check valve, with an eight-shaped blind plate placed between the two valves. In summary: The approach you mentioned does exist, but it is not reliable. The valve installed on the pump outlet side is different in design; it consists of a single valve along with a flange cover, and its purpose is for drainage. This is because when starting or stopping the pump, or when cleaning it, after closing the outlet valve, a drainage valve is needed to drain the remaining fluid

Pick it up quickly; it can be disconnected once the purging is done, right?

There are no specific regulations on this, but it is common practice to use flanges for pressurized flammable and hazardous media; however, this approach is cumbersome, as connections have to be made each time and the blind covers have to be removed