the meaning of "seized open"

[JACEK1]

Hello.

My gate valve is seized open, what can I do?
If your gate valve is seized open and your unable to close it, then the only option would be to drain down. In some cases a plumber can quickly swap the valve over but this doesn’t come with risks. In most cases when you have gate valve problems, it is better to drain down if your gate valve is seized open.


Does "seized open" mean "blocked in an open position"?

 

[teechar]

I take it to mean stuck/jammed in the open position.

 

[Skrej]

Yes. See intransitive definition 2a.

Things can be seized open or shut.

 

[probus]

My gate valve is seized open, what can I do?
If your gate valve is seized open and you're unable to close it, then the only option would be to drain down. In some cases a plumber can quickly swap the valve over but this doesn’t come without risks

Without those two corrections your passage is nonsensical.

A chemical engineer once instructed me to "block closed the gate valve." He just meant close the gate valve. I was to reopen it soon after completing some minor operations. So when it comes to gate valves, apparently block has a technical meaning in addition to its everyday one.

 

[SoothingDave]

Gate valves are a type of "block valve." That is, they are valves designed to block the flow of whatever is in the pipe. They can throttle flow but they aren't the best valve for that.

I think he meant "fully closed" by "block close."