Is it necessary to install valve locks on the shut-off valves before and after the safety valve?

It is generally required to be added, in order to prevent the system from failing due to someone accidentally closing the valve. If no consequences are faced, it can be very serious, hehe:lol

Use a lead seal; it’s much cheaper than a lock

Factories usually make their own valve locks by fitting a sealed steel tube over the handwheel and then locking the steel tube to the valve, so that it cannot be removed.

The method on the 4th floor is similar to that of chain locks, but mistakes are still likely to occur, especially with those double safety valves

According to Paragraph 4 of the requirements for safety valve installation specified in Article 152 of the Code: “. . . For pressure vessels containing media with extremely high, high, or toxic hazard levels, flammable media, corrosive media, viscous media, or valuable media, in order to facilitate the cleaning and replacement of safety valves, a shut-off valve may be installed between the safety valve (rupture disc device) and the vessel, provided that it is approved by the technical responsible person in charge of pressure vessel safety at the using unit and that reliable preventive measures are put in place. During the normal operation of the pressure vessel, the shut-off valve must remain fully open (sealed with a lead seal or locked). . . ” As long as it meets this requirement, it’s fine; any method can be used! It’s not necessarily necessary to add a valve lock! For reference!

Locking it is unsafe; problems can arise if the shut-off valve needs to be closed without a key. A lead seal is usually sufficient, as it is both simple and cost-effective

First, it is necessary to figure out when misoperation of the shut-off valve can occur. The isolation valve is usually closed during system maintenance or equipment replacement, and it is opened again after the work is completed. The shut-off valve does not move during normal operation; therefore, the probability of accidentally operating the shut-off valve during normal operation is very low, unless someone deliberately damages it. Therefore, effectively preventing the cut-off valve from closing accidentally should focus on the operating procedures after system maintenance and equipment replacement. :handshake

Valve locks now all come with key cabinets, so they can’t be lost；

For example, take the dual safety valves: usually one is locked open while the other is locked closed. During inspection, first unlock the one that is locked closed, then remove and unlock the one that is locked open for inspection； Without logic, it’s easy to make mistakes; that backup safety valve didn’t open at all

What device is LZ talking about in terms of safety valves? It’s the first time I’ve heard that pipelines and valves are installed both before and after a safety valve; I need to learn more about this*

It must be locked; valve locks aren’t worth a human life, right, haha.