near boiler pipe insulation

steam247

i have recently covered the near boiler pipes on my steam boiler because they where not insulated and i understand that all the pipe in a steam system should be covered. i used fiberglass. 1 inch is recommended, i could not get 1 inch so i used 2 layers of 1/2 inch. i was able to get at home depot, Is that ok?  the paper jacket is between the 2. can the paper catch fire? also i have noticed on here people use childers mastic to help seal the ends and cover. i would like to do that but can’t find a childers that is used on steam pipes only for chilled water. 

EBEBRATT-Ed

Cover the fittings with PVC pipe covers made for this...Zeston fittings. Secure with special barbed thumbtacks. Stay out of Home Depot their stuff is crap. Order on line. They make elbows and tees covers and end caps thats about it. Mastic is not the thing to use on heat.... it is more like a vapor barrier

EdTheHeaterMan

To answer your question about Fire:
Although Steam pipes do get somewhat hotter than those in a Hot Water boiler system, Those pipes do not get anywhere near the temperature for paper to spontaneously combust and cause a flame.

EdTheHeaterMan

It sounds like you have already started the project using 1/2" thickness insulation, in 3 ft lengths. You need to decide how nice you want the insulated pipes to look. Are you interested in function only or does it need or look good too. You can loosely wrap fiberglass strips around fittings and cover then with aluminum foil and aluminum duct tape. (duct wrap insulation comes to mind) The tape needs to be on a clean surface, and since there is major dust associated with fiberglass insulation, sometimes the only dust free surface is the tape itself so wrapping around the pipe one and a half times to get the tape to stick to itself is the only way to make a permenant seal.


If however you are looking for the type of insulation job that would make it to the cover of The Plumbers Monthly or the Steam Fitters Journal magazine, then the Vinyl Fitting covers are the way to go.

steam247

Thanks, i used 2 inch on pipe then used 2 1/2 inch over the 2 inch and cut some to go around  the fitting. I was having a hard time with it peeling, so i used zip ties temporarily. and was hoping a mastic would help keep it from coming apart. 

ethicalpaul

I wouldn't feel any shame from those zip ties, that is a fine insulation job. Honestly I wouldn't even worry about those elbows, that's a very small area of exposed metal, but yeah anything that looks about like what you have done so far will be fine

EdTheHeaterMan

That looks great. I don't believe you need to worry about mastic/vapor barrier. It's not like chilled water pipes that will sweat condensation all over the place.

You could use this water heater blanket to cut an elbow pattern that will line up nicely
https://www.supplyhouse.com/Rheem-SP57-11C-3-x-48-x-75-Water-Heater-Insulation-Blanket-R11

I might have made something like this pattern from some aluminum faced duct insulation and sealed it with mastic tape. Less messy than brush on or trowel on mastic from a bucket.

https://www.supplyhouse.com/Venture-Tape-1580-2-Duct-Joint-Sealing-Mastik-Tape-2-x-100.

After you cut the pattern, you can peel away some of the insulation so there is only about 1-1/2" attached to the white vinyl. Wrap it around loosely so not to compress the fiberglass. use the mastic tape. to secure it in place. It may look like a swollen knee but if you are careful and persistent, You will get it to look nice. White paint on the mastic tape will finish off the job. (unless there is a white backed mastic tape somewhere)

PC7060

Looks pretty good!  Replace the tie straps with a couple wraps of UL rated aluminum duct tape (one at a time) and you’ll have a good long term solution.