iron pipe cap in radiant

[cory nystul]

I found this cap, it appears to be black iron pipe attached to copper piping. Will black iron in contact with copper corrode /rust like galv. will?

Also what are the views of black iron used in plumbing that contains water such as radiant heating?

31032

[Raymond Wand]

Two dissimilar metals. Galvanic reaction. Better to have used a copper cap. Likely whomever used what was at hand.

Yes black pipe can be used in radiant heating for manifold, supply and returns use only. Should not be buried in concrete or under earth.

[Mark Reinmiller]

Black iron used in heating systems can last forever (not buried in concrete). Oxygen is purged from the system, so corrosion is not an issue.

Copper and black iron certainty can be an issue.

[Jason V. Advani]

Never seen a copper cap, but a brass cap would be fine.