Outside Pipe Insulation

[SLOBuds]

I need to insulate a bunch of exterior pipe. It's colder here in California than you would think!!!

I see a couple of foam products, so which one is best? I'd like to do this only once ... or at least have something that goes for a long long time.

Thanks. Martin

Story:

I laid a few thousand feet of 2" irrigation pipe underground last year. The above-ground branches were then set with pvc ball valves. Almost all of them set in the 'off' position.

We got some very cold weather. A few days with temps below freezing, over 12 hours.

None of the PVC pipes burst, but all of the closed valves did. What a mess, not to say expense too! The ball valves have holes through them for allowing the water to pass, when in the 'open' position. When you 'close' the valve, there is water trapped in the hole which expands and eventually bursts the valve. It must have made a noise because these valves are pretty hefty.

The valves which were open apparently had enough flex to expand with the frozen water. Or else maybe they didn't freeze at all being in contact with a larger mass of water in the long pipes.

 

[Tig]

If you do not irrigate in winter then blow the water out of the lines. Hook a compressor up to the system. Regulate it at 60lbs and blow as much water out as possible. Keep in mind which is the lowest of the sprinkler heads and do that one last. That should clear enough out so it does not get damaged if it freezes.

 

[DocHeb]

Without a temperature gradient (i.e., warmer water moving through the pipe that is in cooler air), the insulation will do nothing. Standing water in pipes will eventually come to ambient temperature, with or without insulation.

If you are not irrigating in the winter, blow out the pipes as above. If you still need to irrigate, crack open all the valves and let a continuous trickle of water drain from the pipes.

 

[marks]

For the exposed loops, there are blankets specifc to that application. I haven't seen any insulation for 2" pipe. Check with Todd Pipe and Supply in Buellton. You may want to consider an expansion chamber, that fills with air and prevents water hammer? Essentially it's just a tee, that extends 6" or so above the loop thus filling with air and allowing for expansion.

Maybe the co-op, or Farm Supply has some ideas?

 

[RonMar]

Docheb hit the main point. Insulation does not keep things warm, it just slows the transfer of heat. You could have a foot of insulation on the pipes and they will still eventually reach the outside airtemp that surrounds them. Best to remove as much of the water as possible and leave the valves open. The water in the pipes below ground will most likley be all right as the earth is a heat source.

 

[SLOBuds]

Thanks all.

Well, it does get cold but it IS California as well ... so we mostly get freezing temperatures overnight then above freezing during the day. Doing something that just slows down the process for a few hours is enough.

I think that I'll just go over to Farm Supply as Marks recommends, and see what they say. We can also drain the lines and leave the valves open. For the most part.

Appreciate the input.

Martin