Yeah that's what i would have used also. One thing he needs to remember though is the valves need to fail in the shut position(you would be surprised how many people make this mistake with machinery....)
Umm, it depends really. In certain situations, you might want valves to fail open it depends on the nature of the chemical, process, and positions in the piping. For instance, you do not want a Valve that is placed down flow of a pump to fail closed.
Case in point, a check valve operates in a manner that flow only goes one way. When installed correctly on a sump pump, it allows flow from sump pit to the discharge point, but does not allow flow back into the sump pit. Yet, if this valve fails, you want it to fail open so that when the pump turns on, water can still flow to the discharge point. You don’t want your pipes bursting or coming apart because the valve failed closed.
I also asked my wife if there are instances where you would want a valve to fail open instead of closed. Since she designs safety systems for chem plant piping and is a P.E., I feel she is a valid source.
Her response...plenty (of times)