Insulation for steam main

Richard Colligan

What size, kind or thickness of fiberglass insulation do I need of a fifty foot horazontal single main steam pipe? We had to remove the old asbestos because of renovation in the basement.

Brad White_27

Depends on pipe size, Richard.

Model energy codes (all that I have seen, there is a common basis) require/recommend 1.5 inch thickness for any steam piping up to 1.25 inch pipe size and 2 inch thickness for 1.5 inch and larger pipe sizes. Most single-family homes with steam piping have mains sized at 2-inch IPS (iron pipe size).

You can get away with less but to do it right, well there is no excuse not to do it right. Sure you can get half-inch at HD, but half-inch is half-**sed, IMHO.

The fact that you are insulating abated pipe should be applauded. How many times have I seen abated pipe and nobody thought that the removed insulation had a purpose? Way too many.

Go forth and insulate. Straight pipes first for best benefit and fittings later if you really want it to look best. And do not forget to insulate the returns too! (1-inch should be fine but not less; the piping is usually under 200 degrees at that point, a break point in the code tables).

gerry gill

we use 1'' wall thickness

on steam heating pipes..why 1''? cause the asbestos were mating up to was always 1' thick, least around these parts..and for 4'' and under piping..

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Brad White_27

What Gerry says is quite practical

when matching the asbestos that was removed. It may not meet code per se, but realistically the first inch does the most work. And most energy codes are not usually policed except by one's conscience and energy waste tolerance. Code authorities tend to rely on affidavits, but that goes to permit-based new work. Simple retrofits I cannot see the hassle IMHO for doing the right thing.

One-inch thick insulation will knock bare pipe losses to 1/6th of what they were. Another inch knocks 16% down to 8%, such are diminishing returns...