In article ,
"Dave Plowman (News)" writes:
In article ,
BigWallop wrote:
If they're soft malleable iron, then they can corrode

I recently removed some (dead) 100 year old gas pipe from the cellar. The
fittings were still in near perfect condition - and unscrewed easily
enough. Think it would be some circumstances where they'd corrode through
in the lifetime of a boiler.

Do you remember the Channel 4 1900 house series?
In converting the house back to how it was in 1900, they had
to reconnect all the old gas pipework which fed the gaslamps.
Although it had been unused for years, it all pressure tested
out OK, and could be reconnected without any remedial action.

--
Andrew Gabriel