May 29 1951’s heat exchanger fire

The locomotive worked its 0730 PaddingtonBristol as usual, arriving at 1020 and then stabling at Bath Road depot. Around an hour later, Driver Matthews prepared to start the turbine but noticed that the temperature warning light was lit and the temperature in the fuel oil pre-heater was excessive. The locomotive was taken out of service and the problem reported to Swindon.

Running Inspector Pullen had seen 18000 pull into Swindon at 0910 and inspected the cab, where he found everything normal. Told it had failed at 1232, he caught the 1300 to Bristol and arrived at Bath Road shed at 1455 and saw Driver Matthews, who prepared to start the turbine. It would not start and Pullen noticed that the temperature in the pre-heater was right round beyond the meter readings. He decided there was something serious happening, so he told Matthews to shut it down completely.

Pullen had noticed some smoke and fumes in No 1 cab when he arrived but reckoned it was not serious. When he checked the generator end of the engine room he found extensive smoke and fumes, the corridor very hot and some smoke coming out of the compressor inlets. He tried to turn the turbine but could not. He reported that the running foreman had noticed discoloration to the heat exchanger covering plates soon after he’d booked on at 1400.

Pullen interviewed Driver Matthews who said he’d had a normal journey from Paddington except for a red ‘temperature before turbine’ light lit just after leaving Paddington. It went out when he reduced power from notch 4 to 3. Matthews disposed of the locomotive at Bristol and was satisfied there were no excessive temperatures. He restarted the turbine without difficulty a little after 1135 but then found the ‘before turbine’ red light shining. Switching the turbine off, the light extinguished when revolutions fell below 200. Again, Matthews started the turbine and, again, the red light shone. He gave up his attempts and asked that another engine be provided for his train.

At 1630, Mechanical Inspector Wiltshire found the heat exchange still excessively hot and saw flames through the inspection glasses of the combustion chamber. He found that paint had burnt off the roof above the heat exchanger and decided not to open the exchanger inspection covers. Instead, he tested the turbine shaft alignment with the hand ratchet and then used the diesel auxiliary generator to turn the turbine to 600rpm to force sufficient air through it to extinguish the flames.

At 1830 he opened the heat exchanger inspection covers and could see the tubes were badly distorted. He kept the turbine turning until 2120 when he considered the locomotive to be in a safe condition.