Piston Shatters Whiile Being Heated -2-8-2T Baldwin

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A volunteer mechanic working to rebuild the cylinders and pistons on a working tanker engine was heating the piston head so that he could weld on metal skirting. He was using a tiger torch and propane bottle. The idea was to heat the piston evenly so that the metal could be added, then machine it back down to bore size for the newly rebored cylinders.

The piston was supported and surrounded on three sides by bricks while it was being heated. It blew apart, sending bricks through two adjacent rooms, one of which rebounded and struch buddy on the thigh. Thankfully, he is okay, but his pride and the piston are goners. They will have to have another cast and machined, hopefully in time for this summer's excursions.

This was reported in the Victoria Times Colonist today. I have only paraphrased.

[GN-Rick]

Where did this happen? I am a little southeast of you.

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In Port Alberni. If you find Nanaimo, then north to Parksville, go due west about 36 km and find Port Alberni at the east end of a long inlet. Usually the hottest place on the Island in the summer. It's a 35 minute ride each way across some fine trestles, with a solid 2-3% grade all the way to the Mill. The McLean Steam Lumber Mill is quite an operation. You spend about 1.5 hours at the Mill, then return to PA.

[Anonymous]

I would like to know the cause. Having been a welder for many years I am curious. It sounds like the piston was stressed or fatigued and should have been preheated in a furnace where the heat could have been applied evenly and gradually to the entire surface. In other words, stress relieved. Also, buildup of material on such parts can be done using a rotary spray welding technique which introduces a more even heating of the substrate. Of course some cast iron is porous and absorbs oil (steam chest oil) and moisture, and will explode when heated regardless of what you do.

Then again, were the bricks firebricks? Were they dry? Non-refractory bricks can explode, as can concrete from steam buildup in water pockets inside the aggregate. Did the piston explode, or the bricks, which broke the stressed casting?

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I don't have the article any longer, but recall that the piston was what exploded. Of course, jounalists are notorious for getting details wrong, so who knows what really happened. There may be some information posted on the website...I have not checked. It is the Alberni Pacific Railway. On the site are two short videos of the engine pulling up the grade toward the only steam saw mill in Canada.