Advice on "Shutdown pannic button" setups....

[mrtangent]

Dear All,

I am after some general advice on or pointers to usefull articles or background reading on which valves/pumps are normally selected by the "shutdown systems" plant shutdown button.

So far in our process hazard review we have worked through our percivable senerios and installed protection as required to mittigate the events we foreseen. However, we are now interpreting the shutdown switch as a catch all button i'm not sure what should/should not be tripped.

Any pointers would be much appreicated.

James

 

[Ashereng]

James,

In the chemical industry, there are some things that are "counter intuitive". I have worked minimally in the chemical industry, and so have limited experience.

One of the items that is "counter intuitive" is that in the case of an emergency shutdown, our reactor stays running. If the reactor goes cold (drops too quickly in temp), the consequence creates a bigger problem.

Your description I believe is too vague - responder will only respond with respect to their own plants and processes, which may or may not help you.

Since you have already done your hazop and mitigated the events forseen, that is pretty much it. You can not mitigate a priori something you can not foresee - despite what the manager says.

I am also interested in what others have to respond with - and have bookmarked this thread.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[sdl]

James:

If I interperet your posting correctly, it appears you are trying to decipher what should shutdown on a plant wide ESD button?

These are not usually included in a PHA or SIL assessment. These are typically treated as panic buttons that are manually activated in the case of an uncontrollable situation. Most of the plants I have worked in have atleast 2 levels: Block and hold (pressurized ESD) and the second as a block and depressure ESD.

Depending on your process, you have to be careful because shutting down a complete process with a single button could create a situation that is more dangerous than the one you are trying to prevent as Ashereng noted in his post (shutting down a reactor).

The company philosophy is also important. I have typically seen operators block and hold the plant and leave the utilities running and the facility circulating. I have only seen one instance where the plant was depressured by operations (fire situation).

Hope this helps as I am not sure I interperted your post correctly.

sdl

 

[MedicineEng]

You can have individual emergency buttons (for instance a pump) and others that stop all your installation. Of course, the situation that you have a emergency button that can stop a reactor where you have a explosive that needs to be maintained at negative temperature is not adequate. In fact in my oppinion you should not have an emergency button for that situation. In our reactors, we don't put local emergency buttons to avoid this situation since we might have the situation described above. The stop can oly be done in DCS or directly in tyhe MCC room.
Is a trade-off: You don't want to have a solution that actually can be worse than the problem.