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Gas Pressure Test - What is good enough

7K views 14 replies 9 participants last post by  log_doc_rob 
#1 ·
I've had my gas piping worked on while my major house reno is getting ready for a rough-in inspection. Plumber has fixed numerous leaks in the gas pipe, but its still leaking. Right now the pipe is holding 15 PSI with about a 1/2-3/4 PSI drop after 24 hours. Is this the best I can expect or should I push for this thing to be holding for a straight 24 hours with no leaks. Most pressure tests I've been able to find reference to online only ask for pressure to hold for 15 min or so, which the system I'm sure would pass. I just want to do whats best for my family, but not beat up the plumber by holding his work to an unreasonable/impossible standard.

Thanks,

BRENT
 
#2 ·
24 hr @ 15 Psi should be fine, working pressure is not even a 1\2 Psi it's generally around 0.7 W.C (Water Column) pressure on most 250,000 BTU residential meters.

Although I would soap test the joints and fittings, especially Black iron fittings from China, they are sand molded and have a tendency to leave perforations in the fittings
 
#4 ·
Did he test the system with the appliances connected? or did he valve off or cap off the individual feeds to each appliance before testing the main line? According to NFPA 54, the national fuel gas code, he's only required to pressure test the line at 1.5 times the working pressure or no less than 3 psi. I find it unlikely your operating pressure is 10 psi, most residential pressures after the meter are 1/2 psi or less like bob said. The test duration of a single family house is a minimum of 10 minutes, not to exceed 24 hours. It sounds like the plumber went above and beyond what pressure he was required to test at and the duration of the test, so you should be fine.
 
#5 ·
Clearly the gas will run at a PSI much much lower than what is tested. All ends are capped as we are still in a rough-in phase. He did also check his meter for leaks and all is well. I think I'm going to go shoot some soapy water on the joints after work and see what comes up. If I can't find anything else I'm going to let him go. Its to code, and technically thats all he really needs to accomplish.
 
#6 ·
When it comes to gas and water, I want ZERO leakage. Even a small gas leak over time (especially if it happens to be in a confined space) can evenually build up into something dangerous.

Now that said, 1/2 to 3/4 PSI pressure differential after 24 hours could be just a change in the temperature. The real question is whether or not the pressure continues to drop (remember that old school formula... PV=nRT ?)
 
#7 · (Edited)
http://en.wikipedia.org/wiki/Zero-risk_bias
Since the public is horrified of gas explosions and all the spin doctors in the world cannot reassure them in this case, the standards probably assure public safety to the same level as helicopter reliability. . .99.9999% safe, 'six nines' reliability.
But, I cannot find anything on the Web to back this up. A number like "residential gas explosions per 100,00 homes per year" would be useful.
Hwy deaths in the US and residential house fires are 40,000 per yr. With 100M homes in the US the chance of yours catching fire is 1 in 2500 per year, and gas explosions must be way less frequent than this. 60 people per year in the US get hit by lightning and this makes news, but I can't remember ever reading about a resi. gas explosion in any local newspaper where I've lived.
 
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