tl;dr: The most efficient end secure way of shielding your fuel tanks on CVs is to stack T3 tanks one on top of the other (the sides with the circles, not the glowing sides) and encasing the stack in normal steel blocks, ending with a 4x3xWhateverLongOrHigh thing. You need to protect your fuel tanks, if they get shot they can explode damaging the surrounding blocks... but how exactly should you protect them? I'll tackle T3 CV fuel tanks first, because CVs have a much steeper price than anything else. The explosion radius is about 4 blocks, with decreasing damage as far as you go, but there is some weird stuff going on. The setup: I shot the tanks from an angle with a rifle, not to contaminate the data with penetrating shots. Results (in points of damage): As you can see, if the explosion is free to expand, it can damage blocks VERY FAR from the tank. Conclusions so far: T3 fuel tanks on CV: - Normal steel is more than enough to contain fuel tank explosions. (even with a chain reaction going on, a block will take at most 64 damage, out of 500 hp) - You should always fully enclose a stack of tanks to avoid damage to the surrounding blocks. - Orientation matters: the downside (blue mesh part) of the tank does more damage than the top. It also matters which side the rotational axis is (axis part does more and more widespread damage). -Stacking order matters. A stack of T3 tanks piled one on top of another never chain reacts, and seems to be the best bet so far. (stacking them by the thin side is giving me inconsistent results so far) T2 fuel tanks on CV: - You can avoid chain explosions only by stacking them on top of one another. T1 fuel tanks on CV: - They always chain explode if stacked. Large O2 tanks on CV: - They never chain explode. (they don't do very much damage exploding too) Fuel Tanks on SV: - you can avoid chain explosions only by stacking them on top of one another (the side with the circle, not the glowing one), otherwise they always chain explode. Explosions in general: - If a tank explosion destroys a block, it stops there. So you could even one-time shield your fuel tanks by bringing me a shrubbery and covering them with potted plants. Since we do not have threadmarks, here are the next posts: - how rotation matters. - CV T3 tanks chain explosion. - CV T2 and T1 tanks chain explosion. Many thanks to @Friendly Timo for his comments, which bugged me enough to actually check for myself, and to @rainyday whose invaluable guides inspired this one. And many thanks to @geostar1024 too, who is very good at inventing new and exciting ways for blowing stuff up, and whose questions made for a way more complete guide.