Ditto. It is very common not to want a unwelcome GFI trip that would interfere with a manufacturing process and often time a GFI alarm would be used to indicate is a GF has been detected so that the process can be shut down in an orderly fashion. However this wouldn't be of much help if a human life is a risk. Is human life the critical issue? If so then there will be trade offs. I agree with kwired that a swimming pool is a different consideration than brewing beer.
What class of GF protection is required in this process, class1 or 'A', or class 2(ELCI-earth leakage current interrupter)?
I have done work in dairy foods processing plants, and GFCI is not used on anything except for 15 and 20 amp 120 volt receptacles intended for general purpose use like portable equipment or tools. Likely similar tanks as OP mentioned in the brewery are in use in dairy processing also.
Pumps, agitators, electro-mechanical valves, sensors, other controls, etc. are all generally hard wired in some way, and there is little risk of losing an equipment grounding conductor. If they were all cord and plug connected, then you have a situation no different than you do for electric construction tools, and extension cords - missing or defective grounding pins on the cord caps, which is what I feel has to be #1 reason why GFCI is required for all temp power outlets for construction purposes, more so than any presence of water.
Faulting equipment with no equipment grounding conductor is not a safe thing - especially if there is a lot of grounded surfaces around. A metal tank that is pretty solidly connected to an equipment grounding conductor that has a fault within equipment mounted on it is going to have low impedance path to make the overcurrent protection work very quickly.