Sizing pipe insulation

jlo1029

I have some uninsulated black iron pipe I'd like to insulate and I'm trying to figure out what size to buy.

Most of my pipes have fiberglass wrap but I'd rather get the clamshell kind for the currently uninsulated ones.

Measured with a string, outside circumference is 5.5 inches. Divided by pi, that gives me 1.75 inches.

But my choices for buying insulation are 1.25, 1.5, 2.

Is 1.5 the right choice?

Thanks...

EBEBRATT-Ed

your a little off.

1 1/4" is 1.66 od
1 1/2" is 1.9 od
2" is 2.375 od

JUGHNE

A flexible sewing measuring tape may give you more accuracy.

You want to be sure to order the correct size, returns probably a hassle.

You could go to a hard ware store and buy a 1 1/4" x 3" long pipe nipple and also a 1 1/2" x 3" nipple. Take them home for comparison to your pipe.
Cheap insurance.

They are close and hard to eyeball sometimes.
For me, I can close my forefinger to thumb around 1 1/4" pipe.
But not on 1 1/2", finger tips will not touch. FWIW

jlo1029

Cloth measuring tape was the way to go. It's clearly 1.25.

So next question... It is worth removing the old fiberglass wrap and replacing with the clamshell kind while I'm at it?

JUGHNE

Depends.....how thick is the wrap, often it is wrapped so tight to be non effective.
And your 1 1/4" must be the returns.....the main might be 2" or so.
You will be impressed with the new clamshell and comparing it to the wrap you might want to change over. Will be some more money for the larger size though.

jlo1029

Cost with only doing the uninsulated ones.. $112.17
Cost to do all.. $221.56

Not planning on doing elbows. My basement needs SOME heat, after all!

Kinda seems like I should just do it all at once while I'm at it!