We need to test a gas copper line for leaks and we're currently using
water at about 115 psi and a pressure gauge, but I am not sure this is
the right approach.
I'd like to ask what is the standard procedure to test a gas copper
line for leaks.
Is water or air used?
At what pressure?
For how long?
What would be an acceptable drop in pressure in this period of time?
Can an unexpensive pressure gauge ($15 or so) be used with water or
Thanks a lot in advance.
Where I live (AZ) the gas is delivered to the residence at ~ 11 ounces of
We do not use copper for gas lines, black iron and galvanized are the
choices we have.
Tests are done with air at 30 psi.
No leaks for 24 hours.
What does the AHJ want you to do?
What does the utility supply and what do they recommend?
One older technician for our local gas company goes around to each joint
with a match. I like to use soapy water. You can also put a tee in the line
with a Schrader valve and use an electronic tire pressure gauge. Any
pressure drop is not acceptable. DO NOT put water inside the tubing.
Propane is often done with copper, mostly compression fittings. As for
sweating with propane in it, yes, it can be done. No., it won't explode.
All of our natural gas lines in commercial and industrial are welded. Yes,
they are sometimes welded with gas in them, but the meter shut off.
We use butane and "type L" copper, which is thicker than normal copper
I am told that type L copper is ok for gas as long as the pipe is safe
from being hit, and with the advantage that copper is more resistent to
corrosion. If the pipe is exposed to physical damage, then galvanized
should be used.
I called my local AHJ, and they pointed me to an official norm that
states to use twice the normal-use pressure for 30 min.
They also pointed me to a certified expert, which I am actually going
to hire to do the testing.
Thanks every body that responded. Your advice was very helpful!
Around here, copper can be used with propane or natural gas. It is not
allowed to have sweated fittings, nor compression fittings, they all must be
flared. The copper must be flexible, not sure of the grade, but it is the
thicker wall pipe.
A long time ago, the only thing you could use for natural gas was black iron
pipe. Years ago, gas suppliers started putting an additive in the gas that
made the use of copper ok, but some local codes were never changed.
I remember when only black iron was allowed. The switch to copper came in
our area when the utility (which I worked for) decided to use copper lines
from the underground to the meter because there was less damage to the
service from frost heaving. The copper would just bend a bit where the black
iron elbows and couplings on the meter could crack or pull loose with solid
My folks had a natural gas line leak killing the grass in a spot just
off the side entrance. The gas company dug it up, then the repair guy
cleaned off the plastic wrapping the pipe. He then took a torch to the
pipe upstream of the leak, heating the pipe to red hot. Then he used a
pair of pliers and crimped the pipe shut, stopping the gas flow. Leaky
section of pipe cut out, new section welded in. Heat the crimped area
red hot again, and finagle it with pliers to open it back up. Tested
for leaks (bubble solution) and finding none, reapply protective pipe
wrap and fill in the hole. Grass grows great now. Oh, this was in the
drop between main line and meter, at least 50ft from the main line, and
at least 75ft from the meter.
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They make a test gauge for gas it has a 3/4 female pipe thread the body has
a gauge attached and a Schrader (sp) valve for a bicycle pump. 15 psi is
normal for residential in my area. I would pump it up and soap the joints. I
can't remember the Time to hold pressure. The PSI can vary From area to area
Type of line welded . Check Local Codes. Remember it's gas so you want to
do it right. test gauge
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