Installed Gas Pipe then had pressure drop after 48 hours

[peej]

I installed iron gas pipe from the meter bar to inside the house and then from there I used csst and ran that to a stove. The fuel source will be natural gas and the meter has not been installed by the gas company yet

I pressurized the line to a little over 5 psi and had pressure loss. Identified 2 leaks and corrected them. Pressurized the whole system from end to end and the pressure held solid for more than 2 days. then it got cold out and the pressure in the line dropped from 5 to about 4.5 and then even colder today and the pressure has dropped down to 2 psi. I am not seeing any bubbles with a heavy soap and water spray at the joints, tees, and shutoffs.

Should the pressure start to dissapate over time naturally if just left there? Looking for some opinions as to what I am seeing .

5 psi at 46 degrees outside
4.5 psi at 35 degrees outside
2 psi at 30 degrees outside

thoughts please

 

[Diehard]

Well I'm pretty sure that the 3 psi drop in pressure was not due to the 16 degree drop in temperature.
Something doesn't sound right since you held pressure for 2 days.
What is the pressure range of your gauge? 0 to ?

 

[peej]

this is the type of gage I'm using

 

[Diehard]

Just making sure it wasn't a much higher pressure range. I would expect that gauge would have reasonably accurate readings in the area you are dealing with.

 

[peej]

these images below show the iron piping done outside and the transition inside and the further transition from 3/4 to 1/2 inch as well as the termination plate for the stove connection - just for a visual -

I had to loop the iron pipe under and over because I didn't think it would have landed inside in a place that I would be able to work with it.

 

[peej]

found the leak - its where the gas meter will hang - and where the test gage is now - I'll throw some muscle at it when I get home and that should do it.

 

[ExtraMilePlumbing]

Fastest way to find a gas leak is pressurize line to 80 psi, at that pressure you should here it whittling

 

[chiraldude]

Interesting. Sounds like the drop in temperature caused one part of the connection to contract more than the other, resulting in a leak. I wonder how often this happens?
Muscle power should fix it. The one thing that surprised me most the first time I installed iron gas pipe was how much force was required to seal the threads.

 

[wood4d]

you cant test gas pressure off the meter connection. You have to cap it where you have the union and check it where you have the tee with a plug. your lines are probably fine

 

[Mr_David]

you cant test gas pressure off the meter connection. You have to cap it where you have the union and check it where you have the tee with a plug. your lines are probably fine

#1 post - meter has NOT been installed yet

Code here requires 15 psi pressure test.
That means you have to remove all rotor valves and cap line because they typically have a max rating of 5 psi.
Why do you have 2 valves in middle of the system?

 

[mike fiore]

also make sure youre iso;ated from the diaphragm. it will blow off if pressure gets to high. or above its pressure rating.

 

[breplum]

All plumbing codes require galvanized pipe and fittings above grade outdoors.

 

[frodo]

all exposed gas piping shall be painted

#1 post - meter has NOT been installed yet

Code here requires 15 psi pressure test.
That means you have to remove all rotor valves and cap line because they typically have a max rating of 5 psi.
Why do you have 2 valves in middle of the system?

Why do you have 2 valves in middle of the system?

the exposed black pipe has to be painted

 

[CT18]

Damn that appliance has 4 shut offs. We paint all exterior black pipe.

 

[frodo]

All plumbing codes require galvanized pipe and fittings above grade outdoors.

I have never seen that code
I have run miles of Black pipe on roof tops of schools, hospitals, Prisons, houses etc etc
strap the pipe to 4x4's - on 2'x2' rubber mats then painted the pipe.

 

[FishScreener]

To paraphrase the old corrosion engineer, who explained it to me: If you paint black pipe, then any scratch in the paint becomes the locus of all the corrosion potential for the entire pipe, and can rapidly rust out. Same happens if you nick the galvanizing, the pipe corrodes there. That’s why galvanized frequently rusts at the threaded connections, where the galvanizing is cut off.

This point corrosion, is why gas pipe is black. Painting it defeats the whole purpose of using black pipe.

 

[frodo]

To paraphrase the old corrosion engineer, who explained it to me: If you paint black pipe, then any scratch in the paint becomes the locus of all the corrosion potential for the entire pipe, and can rapidly rust out. Same happens if you nick the galvanizing, the pipe corrodes there. That’s why galvanized frequently rusts at the threaded connections, where the galvanizing is cut off.

This point corrosion, is why gas pipe is black. Painting it defeats the whole purpose of using black pipe.

.galvanize pipe is not used [in this region] because of the galvanizing flaking off an fouling orifices
the code states exterior gas piping be coated to protect from elements
using it will get you a red ticket from the inspector
we also can not use galv fittings, they must be black