I feel for the gentleman who was so badly burned: possibly one of the most painful and long lasting of injuries and I applaud his willingness to share his experience with others. Since the article referred to in Simon’s post is done as a safety service (“to save a life or two”), I feel inclined to make a few comments.
The following is my take on the issues at hand: please confirm with your own research and consultation with experts.
Dabbing connections with soapy water in the way the article describes is a great diagnostic tool if you are looking for a known leak and you are trying to locate the leak, but it is a poor way of checking for system integrity. This is clearly the case in this report as it is the long stretch of metal piping where the leak occurred. This might be even more likely for hose, even proper propane hose.
I believe the best way to test for system integrity is with a manometer administered by someone trained and experienced in its use. The next best thing (and one you can oneself) might be to have a pressure gauge in line. Charge the system up to all appliances attached to propane distribution (for most boats that would be the stove alone). Turn off the stove burners, but leave all valves to the appliances open. Close the valve on the tank and watch the gauge. If the gauge holds steady, your system is not leaking: if the gauge drops steadily, even if slowly, you have a leak.
I do the above gauge test every time I put on a new bottle.
Alchemy’s propane system: I believe a properly set-up propane system to be among the safest ways to cook on a boat.
1. A pressure gauge in line to allow for testing system integrity as mentioned above.
2. A solenoid valve in the propane locker (drains overboard) that is controlled by a switch near the stove, the only propane user. The solenoid is regularly tested.
3. There are 2 sniffers (I have 2 separate bilges and for redundancy) for gas fumes designed (if memory serves) to set off an alarm at 20% of the gas density required for ignition. These also are regularly tested for functioning and the alarm can be heard in the cockpit with the engine running. They demand very little in the way of battery power.
With the above, I have many years of mostly live-aboard cruising without much of a worry.
This is a fairly common US set-up, but I also believe that UK and/or EU regs may differ and lead in other directions.
My best, Dick Stevenson, s/v Alchemy