Black pipe question for you installers

I'm installing a gas (wood)stove in my vacation cabin. The existing natural gas piping runs around the outside of the brick and there isn't a single union anywhere. In order to tee into the pipe I was going to saw into the pipe where I want to install the tee but I'm not sure how to do it safely. Best idea I can come up with is to turn off the gas at the meter & disconnect it there. Also disconnect at my water heater which is the farthest termination point. Use compressor to flow air through the pipe to hopefully eliminate the explosion hazard and then saw the pipe & proceed with the plumbing.

Sound like the best way to do it?

Also--is it OK to use a union outdoors? If not that would explain why there aren't any.

I believe you don't want a union on the outside of the structure for several reasons one of which is corrosion. Might have to find a plumbing forum and ask a few questions. What size is the line heading through the wall of the house?

As for flushing the gas line shut the line off at the meter and when you tap into the line see if you can find and elbow or other fitting inside where you may be able to detach the line and add a tee instead. This is what I did when I re-piped my water heater gas line.

ALL the gas pipe is outside with only a short length punched thru the wall directly to each heater.

Just a couple of questions for you;

Do you have a way to thread your black pipe after cutting?

Do you have experience doing gasfitting work?

The answer to the union question is yes, you can use a union outdoors but like any steel product it must be coated with a paint product in order to prevent corrosion.

If you do not have experience working with black pipe I do not recommend venturing into this project. Black pipe needs to be threaded a certain amount depending in diameter. It can be overthreaded and underthreaded. It also needs to be sized properly for your appliance and the entire system needs to be sized for BTU load. Your appliance may take it into a new pipe size for the entire system.

I would be happy to answer any questions you may have but keep in mind I would much rather see you hire a gasfitting professional than try to take on a project that normally requires many years of experience to perfect. There is quite a process involved installing an appliance properly including clearances, drip/dirt pockets, shut off valves in certain locations, pipe identification, venting (I can spend hours explaining venting) and other safety related items that you should be trained on.

I hope you do the right thing but most importantly if you do it, do it safe and by the book.

P.S. By the way if you blow compressed air into your gas line you will likely blow the small regulators on every appliance in that line. They are rated for a max pressure of 1/2 psi.

Thanks for the tips. I did the job last weekend. As mentioned I shut off the valve at the meter, opened both ends of the gas pipe, turned off all valves (there is one at each appliance), and hooked up a compressor & regulator set to a 5psi limit to evacuate the open pipe. When no gas smell could be detected I waited a couple more minutes and then sawed the pipe near where I wanted to install my tee. I have a complete set of dies and a stout pipe vise that I've used in the past to pipe my house and woodshop. I'm not a gas expert but I did stay at a Holiday Inn Express recently ;-)
Seriously between common sense and internet research this was a simple job.
The stove & the Duravent pieces all came with extensive instructions, and of course lots more cautions, so I'm confident my installation and venting is to code. It's certainly far better than most of my neighbor's old-school installations. I chose to install a gas stove because I couldn't install a wood stove safely without extensive remodeling.

Sounds like a good installation. Glad to hear you stayed at a Holiday Inn Express cause otherwise who know what would have happened! It's good to hear you did your research and all that as you are right, there are plenty of half-assed jobs out there that are unsafe.

I just noticed you're in Canada. My install probably wouldn't pass YOUR codes.