insulating blanket in steamers?

Probably yes, if it isn't too expensive.

Insulation is used today and it was used back in the steam days, too.

Between the boiler shell and the outer jacket (the part you see) is 3" to 5 " of space. Insulating material is placed in that space. It used to be Asbestos, but that's not used now, of course. There are many other materials used today and some of them may be made by the company you worked for. The proper names of the various materials escapes me at the moment, so perhaps someone who can remember the details will post more info here about this.

Despite the drawbacks of asbestos, it generally did its assigned tasks very well.  I have always wondered if the modern steam engine boiler insulation is as efficient at holding in heat as the asbestos was.

This was sold as or under the trade name of the company.  I don't wish and can't discuss any details with the parting agreement signed. With its use in extra hot industrial applications,  I would guess it could be used in steam engines. There are better products now that could avoid the moisture problem. 

I actually thought I saw it in the picture. 

Dieselbob posted:

Despite the drawbacks of asbestos, it generally did its assigned tasks very well.  I have always wondered if the modern steam engine boiler insulation is as efficient at holding in heat as the asbestos was.

Having worked on steam locomotives that still had asbestos insulation under the jacket, I can tell you that the jacket was still pretty hot to the touch. When thick fiberglass insulation battens were used on the second 4449 overhaul (1983/1984 for the New Orleans Worlds Fair Daylight trip), one could lean up against the jacket, while working on a Dynamo, and NOT burn your knees through your pants., i.e. a LOT cooler than the old asbestos crap.

I know this isn't an example from a full size locomotive, but I've made use of Fiberfrax products on my live steam locomotives.  It isn't necessary under the jacket - my engines only run at 125 PSI, so the barrel doesn't get much over 350 degrees F - I actually use fiberglass insulation designed for automotive exhaust applications for that.  However, I have found Fiberfrax useful for certain applications in the smokebox and firebox.  Full throttle pulls upgrade will result in a white hot fire, and the Fiberfrax handles it without any problem.  For my applications, it is easier to install and remove than traditional firebrick or refractory.

These days on steam equipment and industrial furnace and piping applications, you see a lot of fiberglass insulation products and ceramic wool. A lot of the ceramic fiber is aluminum/silicate based.

That name is "familiar" to me. I believe that's the replacement for asbestos blanket although no one ever uses that comparison out loud!

I forgot to mention that I believe it's not that expensive. I never thought about use in steam engines until I saw the product on a tear down scene. There are now spray on versions.

I also worked in Michigan for an engineer that worked with NASA. He designed high temp products like rocket nozzles. He taught me how to cast ceramics from slurry, that would be used in the manufacture of aluminum. We tucked our custom "home-made" furnace with the blanket to cook that stuff, where brick couldn't be used.