Shay - Painting
& Assembling The Boiler
The goal here is to:
Lagging: The lagging used on the full size boilers is a hard material. I assume it contained asbestos in the early days . Suspect the current versions don't. I saw a freshly lagged boiler at Cass 20+ years ago. As I recall the lagging came in blocks about the size of bricks and was held in place by a plaster like material. I checked what McMaster-Carr and found a 1/4" alumina-silica fiber insulation (93315K61) that looked like it would work.
The day before I was set to apply the insulation Dan Staron called to talk about progress on our shays. When I mentioned boiler lagging he suggested that I consult Chuck Hackett's webpage. Chuck had run some tests on boiler insulation and concluded that lagging is no better than trapped air under a jacket. The lagging is however useful in preventing dents in the jacket. And here I was getting ready to install insulation that has little if any insulating value and is so soft it won't prevent dents.
I had asked Ed Perry for lagging advice some time back and he said that he had used cork sheets on a couple boilers. The McMaster-Carr site suggests cork is good for gaskets up to about 180 degrees F. Another section says cork insulation is good up to 266 degrees F. The maximum temperature inside the boiler will be about 340 degrees F (100 psi steam). There should be a gradient as one gets closer to the outside so that a guess is that the maximum temperature of the insulation will be about 300 degrees F. This is a little above the max operating temperature temperature I'd found for cork, but should be in the operating margins (if the speed limit is 70, you can usually get by at 75).
The next task is to clean up the workshop, then on to painting and installing the plumbing and miscellaneous parts.