Help, seal/fill metal pipe with foam sealant

[SnickarNicke]

I need to seal old metal pipes that are about 50mm in diameter and I'm considering using expanding foam.

The pipes lead to an old oil tank that is no longer in use and the pipes will be underground (the tank is located outside and underground).

- Does expanding foam work for this or do you have any other good suggestions?

 

[norrbottenstorpet]

Most 1-component foams don't have enough closed cells to be "waterproof." So there is some moisture migration in the material. But it will probably work.

One problem might be that the length of the pipe means you have to apply it through a hose. The foam cures upon contact with the air's moisture, so you'll either need to moisten it slightly with a spray bottle or apply the foam in stages. You can't apply very thick layers; otherwise, the foam won't cure deep inside.

 

[SnickarNicke]

Anyone have a better suggestion than skum?

 

[norrbottenstorpet]

How is the pipe situated, how long is it? Is it the fill pipe to the oil tank? Then there should be a cap on the end, so moisture isn't a major issue. However, the inside of the pipe is likely very oily, so regardless of the sealing method you choose, it needs to be cleaned first.

If so, why does it need to be sealed?

 

[SnickarNicke]

How is the pipe located, how long is it? Is it the fill pipe to the oil tank? Then there's a cap at the end, so moisture isn't a major problem. However, the pipe is likely very oily inside, so regardless of the sealing method you choose, it needs to be cleaned first.

If so, why does it need to be sealed?

I cut off the pipes to the oil tank because they were in the way when I was insulating the wall externally. The oil hasn't been used since '76 and I have no plans to buy more.

I found good plastic pipes which I glued in place and it turned out better than expected. The Fix-it tube that I had used previously fit perfectly.

The problem is solved and the pipes are underground again.