Burst disks????

[OutlawCaver]

There is a huge difference between plugging or double discing versus installing single burst discs of a range higher than the rated value from a fireman's perspective:

Plugging a burst disc port with a bolt or molten lead does not allow for the escape of gas in a fire. This is potential bomb for sure. Given a fire where the heating of the tanks is predominately due to convectional heat exchange, a 5000psi rated burst disc will blow on a set of doubles filled to 3000psi at room temperature, at approximately 400 deg F (assuming minimal expansion leading to an increase in volume) which is still 200 deg F below the melting point of lead and much much less than that of a steel bolt (1200 deg F or more). Hopefully, the nylon seats in the valve and viton or rubber Orings would melt somewhere around 370-660 deg F and release the gas through the valve stem, neck threads or manifold.

Moral of this story: If you plug or double disc your tanks, there is no safe haven if they get caught in a fire and are heated faster than the lower melting point materials can fail and harmlessly release the tank constituents.