Thanks. Can you confirm if the following is correct?
Going by vanilla mechanics, an explosion ray can have max strength intensity x 1.7, and a block reduces this by (resistance+.3) x .3, so to have a chance to break reinforced concrete (res. 48), an explosion needs intensity a little more than 8.5.
The formula for single block boilers is sqrt(steam)/100. Setting it equal to 8.5 gets a required steam amount of more than 720k, so a strong tungsten boiler at 512k would not destroy it. I don’t remember if there was a 1024HU/t boiler, but if it exists, ot would hold 1024k steam and could destroy reinforced concrete.
Multiblocks have power 2 + sqrt(steam)/1000, so they would need more than 42m steam. I don’t remember the multiblock boiler stats but I guess this would correspond with the third tier of multiblock boiler, since the stainless boiler is 4096HU/t and 4096 x 4 x 4 = 65k > 42k.
So it seems like a layer of reinforced concrete should be enough for 512HU/t single boilers or 16k HU/t multiboilers.
According to this, normal concrete (res. 24 iirc) can block < 184HU/t boilers or < 5236 HU/t multiboiler (so stainless/invar).