I’ve done that before. BOOM.
I wire up shutdown circuits to sticky pistons with bricks to cut off the burning boxes if either the water input stops or the pressure is too high.
The gibble-o-meter can be setup to emit when overpressure, but you’ll have to measure the normal operating pressure first. If the pressure is too high to fit on the screen, switch it to hex mode! Damn GT is smart.
I will use a drum next to the boiler array to store the distilled water with a fluid-o-meter on it. If it ever measures 0, emit to stop. That way there is still some water in the pipes, but the supply has ceased and we should stop before a dangerous condition results.
Finally finding some blast proof rocks (ie: black granite) can help isolate the damage. I know boilers are scary, so I put them away from my main storage in the back of my base. Then I build a room around them of high blast stone. It won’t stop it completely, but helps.
I’ve considered setting up my boilers underwater to see if that would completely nerf the explosion. Food for though!