Old gas lighting pipes all over the house – how do I cap them?

[Stephen]

Hey folks! Not sure if this counts as plumbing, but figured I’d ask here.

Just moved into an 1880s Queen Anne house that still has the original gas lighting setup. There are a bunch of 1/2" gas pipes sticking out of the walls and ceilings — looks like they used to be for sconces and chandeliers. They all connect to the same gas line as the fireplaces.

Right now, the gas is shut off, but if I turn the valve back on, gas would come out of all these open pipes.

What I want: Use the fireplaces like they were meant to be used.
The problem: I need to cap off all these open pipes (they're not threaded), and then pressure test everything to make sure there aren’t any leaks hiding in the walls or ceilings.

Anyone done this before? Best way to cap them? Anything I should watch out for safety-wise?

 

[Fanatic]

You could skip all the old piping after the main shutoff and just run new gas lines to the fireplaces — probably way less work and way safer too.

 

[Carl B.]

Honestly, I’d be pretty nervous relying on 140-year-old gas pipes. I imagine most insurance companies wouldn’t be too happy about that either.

And yeah, back in the day, the gas wasn’t as refined, it might’ve had all sorts of stuff in it, like moisture and sulphur, which could’ve eaten away at the inside of the pipes over time.