European boats typically have a series of LPG installation requirements, each of which is intended to improve safety and all of which produce additional weak points. One is the insistence on solid copper tubing; it lasts much longer than LPG hose (which the gas makes rigid over time) but wears far less well in just the scenario Mark describes - pentrating a solid bulkhead (or for that matter, accepting chafe from any source). Another is the 'bubbler' sometimes manadated, which is intended to detect the presence of gas leaking past the solenoid or tank valve and which creates multiple additional joints in the LPG piping, each with their own potential problems. The overarching lession seems to be not to depend on regulation or common practice to protect boat & crew when it comes to LPG, but to inspect & test the whole system routinely. We can think of it as life insurance.
Mark, it's good to hear no one lost their life in your explosion. How's the boat doing - much damage to repair? Hope the cruise continues soon.