Black iron pipe for underground run?

[dogwood]

Hi folks. I'm building a 24' x 32' wood shop detached from the house, and about ten-fifteen feet from the indoor wood boiler's 1000 gallon storage tank. I'm going to bury underground a run of pipe that distance from storage to and from the shop. My heating system piping is all black iron. Could I run this short length of pipe in black iron too, somehow so it wouldn't rust, or would it be better to transition to another material for the underground portion of the run.

I'll be hooking the pipe up to a Modine unit in the shop. Thanks for any advice.

Mike

 

[peakbagger]

Unless you have active galvanic protection running in the trench uncoated black iron is bad idea for direct burial. Thin wall stainless steel pipe or copper are the best options that will take the temperature. Coated carbon steel pipe can work as long as the coating is continuous, leave a few voids and galvanic corrosion will find the voids quickly.

 

[E Yoder]

Curious if you considered insulated Pex? It's quite common and works very well.

 

[dogwood]

Peakbagger thanks for the ideas. Do you know if there are any problems connecting stainless directly into black iron? I wouldn't think so, but you never know. And how would you insulate that or copper underground to prevent line loss?

E Yoder, insulated pex might be a good idea. Do you bury that material directly in the soil? I've never used pex so I''d have to figure out how to transition to the existing black iron piping. There must be some kind of fittings for that. I haven't figured out the size pipe or capacity Modine to use yet. Is insulated pex commonly available in different diameters? I'll check Pex Supply's (or whatever they changed their name to) site and see what, if anything they have available.

The only idea I've come up with so far on my own is to run a ten foot or longer length of 3" pvc drain pipe underground from the house to the shop to create a pipe chase and thread whatever pipe I use through that. I only thought of that because I've had an extra length of 3" pvc pipe sitting out in the garage for 25 years unused and taking up space. I wrote in with the hope of finding some better solutions to that Rube Goldberg idea before I start trenching for the foundation footing soon. Thanks,

Mike

 

[E Yoder]

Most dealers for outdoor wood boilers would have pre-insulated pex pipe available that can be direct buried. I don't think supplyhouse.com (pexsupply) has stuff for direct bury. Or Google " underground insulated pex" .
But really for that short of a run you could insulate the pex yourself and pull it through the PVC.
Uninsulated pipe is a waste, melting snow.
There are threaded pex adapters available at supplyhouse.
Pex is reliable and extremely easy to use.

 

[peakbagger]

I had assumed you wanted to run carbon steel as Pex wasn't a good fit for your application. Hard to beat the preinsulated PEX piping systems supplied for OWBs.

If you did go with copper or stainless you can buy isolation unions that are insulated so that there is no galvanic action between dissimilar metals. If your water isn't aggressive it usually doesn't make a difference .

 

[dogwood]

I wanted to go with the black iron because I've a bunch of left over fittings and shorts still laying around that I could utilize. And using inexpensive black iron is an excuse to use my vintage Beaver A pipe threading machine once more. Then I can continue to not figure out how to use pex which is probably a much more the sensible way to go underground, nor worry about galvanic action for that matter. I probably have some old copper fittings around, and could go that way as you mentioned, putting a brass transition to the copper to avoid galvanic action, and then use standard pipe insulation around the copper inside that 3" pvc. That would be relatively painless.

Come to think of it E Yoder, there used to be an OWB dealer heading down your way on 220 between Roanoke and Rocky Mount . Maybe he'd have a section of that insulated pex I could lay my hands on and see how to hook it up, Then I could snake some pex to fittings on the storage tank without too much difficulty and/or remodeling. You've both got me thinking. Thanks again.

Mike

 

[E Yoder]

Yup, he's still there I think. We're just west about an hour.

 

[dogwood]

Thanks E Yoder. I'm about 45 minutes north of there in Botetourt. Looks like a short road trip may be in order. Hope it cools off a little here to before I start digging trenches. Cutting down some big old dead locust for firewood in today's heat about did me in today.

Mike