Blocked In - PSV Isolation

Inefficient MOC and process safety management. Block valves added to isolate PSV and allow for online switch over between exchangers.
The exchanger operated without over pressure protection.
It took only 3 minutes to explode after opening the hot water feed valve.
MOC is not a matter of documentation
CSB Investigation
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[@samar0aggarwal]

Hello Baher, it is very nice video. How can I download it for my reference later?

[@baherelsheikh4942]

Some online tools are available for that.

[@alphaindustries5775]

This is a video from the CSB youtube channel

[@jacobbartlett9400]

This is absolutely insane. Complete lack of common sense. Anybody with basic common sense would know you don't install isolation valves to shut in heat exchangers or pumps without installing proper pressure relief valves. What was the setback? Would they have to add stacks to the relief valves so gas could reasonably dissipate and didn't want to go through the expense? Engineers, either over engineered or under engineered.