The Steamboating Forum

What is the right way to insulate the main steam pipe

Inexpensive: Cotton "sash cord" or "clothes line" wrapped closely around a surface that has a high temp rust inhibiting paint; finish with a couple of coats of paint, color coded if you're inclined.

Moderate: High temp, preformed (looks like household pipe insulation, but rated for high temp). Only draw back is foil backed white paper covering which damages easily, even with several coats of marine paint.

Best: Above insulation with a special sheet metal cover that is fitted and fastened over the paper. The insulation and cheet metal cover are available in the PacNW of the USA from E.J.Bartells.

Ask the people you buy it from how to enclose various elbows, Ts, valves, etc. You can make some pretty nice covers with a contracter's utility knife.

As Ron indicates, cotton rope is pretty ideal for insulating much of steam launch piping. Be sure to get pure cotton rope, much of the stuff that is sold today is poly (plastic) clothesline rope, definitely not for wrapping a hot steam pipe. With highly superheated steam, the cotton wrap can be burn or even catch fire, so pay attention to this.

The bottom photo shows cotton wrap that was on a steam line at about 700F, way too hot.

Aluminum foil makes a decent insulation for steam pipes, it is inexpensive, can take lots more temperature than many other insulation materials, and forms quickly around most equipment. A few layers of foil provides a good barrier to heat flow, but it looks terrible in my view. The US Navy was considering it as the primary insulation material for warship steam plants 100 years ago, but it turned out too expensive back then.

When doing cotton wrap insulation, I always put a couple of layers of aluminum foil around the pipe before wrapping.

Another option is ready made split fiberglass insulation. Home Depot sells the stuff and it goes onto straight pipe quickly, is good for our steam temperatures, and comes with an outer cover that tapes together. Elbows and valves require a little creative fiberglass work and heat proof tape.