Looking for advice on black iron gas line

[chuckisduck]

I got the wc calculated, figured out physically how to get it in the hard spots as well as calculating length to cut. The only union will be outside at the meter.

I know how to static pressure test and pinged the Snohomish inspectors to see if it has to be done in front of them, I plan to permit it and be safe.

I have piped 3/4 in the past but only about a dozen feet of turns, valves and trap catch.

Looking for advice about avoiding galvanic corrosion, making sure I don't violate any code, and if there is any thing about using 1-1/4 schedule 40 I should know about. Advice and knowledge is appreciated.

I do have a segment were it will probably make contact with the ductwork, as shown in the picture. I don't think it's an issue touching galvanized steel ductwork, but thinking of covering with PVC tape in case. Wood in the picture that would be notched is not load bearing.

You do not have the required permissions to view the files attached to this post.

[RocketScott]

The last house I did I was able to reuse all the old gas pipe. Got it close enough then bought a few pieces of the exact length I needed to connect the appliances

You'll need to pressurize the system a day in advance of the inspection. The gas meter needs to be disconnected and capped, otherwise the meter will spin backwards when you go to pressurize it. You only need 15 psi IIRC, a bike pump works. I failed my first inspection because the gauge was crap. It showed 15 PSI until the inspector tapped it and it dropped to 0

Padding the pipe next to the duct would be smart. It will probably make funny noises if you don't as things expand and contract

You can ground the pipes if you want, I don't beleive that's required but it couldn't hurt. As long as you don't end up with stray voltage trying to find ground through the gas pipes. That used to be a problem before code required separate ground rods

Put in extra stub outs wherever you think you might want one later. On my house I added one in the crawlspace going toward the kitchen in case someone wanted to add a gas range or supply a BBQ on the patio. I threw the old elctric water heater back in since I was selling the place but put a stub out in case they wasnt to switch out for gas later

Rectum seal all the things

[Arisaka]

As a metallurgical engineer I can address your galvanic corrosion concern: you will have no corrosion issue with black iron touching galvanized hvac ducting.

[chuckisduck]

Thanks, it what I thought also with zinc being the sacrificial anode and zinc oxide being much more stable than iron oxide. I would still be worried if harmonic vibrations of the duct work where the zinc oxide touches the iron pipe would sheer off the zinc oxide later. Probably over thinking it.

As a metallurgical engineer I can address your galvanic corrosion concern: you will have no corrosion issue with black iron touching galvanized hvac ducting.

[Kolat]

Thanks, it what I thought also with zinc being the sacrificial anode and zinc oxide being much more stable than iron oxide. I would still be worried if harmonic vibrations of the duct work where the zinc oxide touches the iron pipe would sheer off the zinc oxide later. Probably over thinking it.

As a metallurgical engineer I can address your galvanic corrosion concern: you will have no corrosion issue with black iron touching galvanized hvac ducting.

Definitely over thinking it. I usually test at 50 psi on a 100lb gauge.

Code says 10lbs minimum, and you would use a 15 or 20lb gauge for that test.

Gauges are only actually accurate in the middle part of their range.

[chuckisduck]

Thanks, it what I thought also with zinc being the sacrificial anode and zinc oxide being much more stable than iron oxide. I would still be worried if harmonic vibrations of the duct work where the zinc oxide touches the iron pipe would sheer off the zinc oxide later. Probably over thinking it.

As a metallurgical engineer I can address your galvanic corrosion concern: you will have no corrosion issue with black iron touching galvanized hvac ducting.

Definitely over thinking it. I usually test at 50 psi on a 100lb gauge.

Code says 10lbs minimum, and you would use a 15 or 20lb gauge for that test.

Gauges are only actually accurate in the middle part of their range.

Thanks, do you know if the halfway is a minimum can you go higher on the gauge? I have a 0-30 psi and would like to test at 25 psi.

Working my way from the middle outward since there is some geometry that is fairly complex in the retrofit. Glad they have unions at the meter.

[Kolat]

I've pegged gauges all the time for testing. 99.9% of inspectors will be fine with it.

[RocketScott]

Thanks, do you know if the halfway is a minimum can you go higher on the gauge? I have a 0-30 psi and would like to test at 25 psi.

Working my way from the middle outward since there is some geometry that is fairly complex in the retrofit. Glad they have unions at the meter.

That should be fine. You're just making sure it will hold the >1 psi of natural gas pressure

The test guages they sell at the box stores go to 15 psi. The advantage of that is it's easier to see a small drop in pressure. 1 psi on that guage is a lot easier to see than on a 250 psi gauge

[Arisaka]

The leak test isn’t difficult to pass. Just use pipe dope on all threaded joints and sink the threads deep.

[chuckisduck]

The leak test isn’t difficult to pass. Just use pipe dope on all threaded joints and sink the threads deep.

About 35' in with 1-1/4 and did a pressure test halfway through just to make sure. Holds at 20 for 4 hours. I have to temporarily reroute some existing black iron being used, so on hold for a long free Saturday to make sure gas is not down a while. Bought some snoop just in case for that.

[JohnMBrowning]

Yeah - you picked the wrong week to disconnect a gas line....

[chuckisduck]

Yeah, not a good weekend. Luckily it's just a small run of 1/2 black iron with csst (all unbonded and installed by a licensed plumber). I really need to get the line into the occupied area before I finish all breakout line. Final shutdown will be an easy one as it's just the outside penetration to the union at the meter.

I do want to get it permitted, but don't want to have gas down waiting for the pressure test viewed by the inspector.

[chuckisduck]

Finished it a while back, fully successful but never want to instal gas lines after a rough in, at least these pipes will last a lifetime.

The only surprise during the first inspection was they wanted to see my line sizing calculations in BTUs and pipe size/length using tables and didn't like that I calculated as a factor of WC loss.

You do not have the required permissions to view the files attached to this post.

[Arisaka]

Good to see you painted the pipe. Inspectors always want to see the outside pipes painted