I read with interest the report in Maritime FEEDBACK 45 where the reporter applied heat to a blocked pipe in order to help release a blockage. The sudden release of the clogged material due to the residual pressure caused the blocked material to hit the bulkhead. This reminded me of an incident when I needed to release a tiller bar that was corroded to the rudder arm on a narrowboat. Unbeknown to anyone, the wooden handle at the other end of the tiller bar had somehow, over many years, allowed water to seep into the hollow tiller bar. Using a blow torch I applied heat to the seized joint and this unintentionally caused the residual water to heat up, expand into steam and eventually caused the handle to blow out of the end of the tube, immediately followed by hot water and steam causing burns to the hands and arm of my assistant.
Reporter’s Lessons learned: Whilst I have never encountered or heard of anything like this before, my message is always allow for the unexpected! We now always drill a hole in the bottom of the tube first to see if water is in the tube before heating, plus it ensures the pressure can’t increase.