Help: Interlock sequencing scheme
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The steam main is equipped with 3 independent safety valves (two open-type LO, one closed-type LC). There is a shut-off valve (gate valve) in front of each safety valve. How can interlocking be achieved among these 3 shut-off valves (gate valves)? Please provide a solution. Note: It is not about opening the seal with lead or closing it with lead.
There are such valves, valves with locks. In China, there seems to be: Rock valve locks
Yes, I have seen valve stems with locks. Three locks with 2 keys, or three locks with 1 key.
I really haven’t seen it; I really want to learn it*. I want to learn it*
Why isn’t using a lead seal sufficient? It’s very effective, practical, and cost-effective. Using a valve with a lock is good, but it’s more expensive. If too many of such valves are used, management becomes less efficient compared to using lead seals.