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Natural Gas Pipe Test Pressure?

Michael.L

Michael.L

Registered User
Joined
May 10, 2018
Messages
206
Location
Boulder County, CO
This is for commercial tenant improvements for a food service establishment. My city is currently operating under the 2015 International Fuel Gas Code.

Section 406.4.1 of the 2015 IFC reads as follows:

406.4.1 Test Pressure
The test pressure to be used shall not be less than 1½ times the proposed maximum working pressure, but not less than 3 psig (20 kPa gauge), irrespective of design pressure. Where the test pressure exceeds 125 psig (862 kPa gauge), the test pressure shall not exceed a value that produces a hoop stress in the piping greater than 50 percent of the specified minimum yield strength of the pipe.
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Our gas service is supplied by the utility company at less than 10-in w.c. (IIRC, the utility rep told me they could only give us ~7.5-in w.c.). Our gas appliances are rated for a maximum of 14-in w.c.

Even assuming that the gas were supplied at the maximum acceptable (14-in w.c.), that's only ~0.5 psi and 1½ times that is 0.75 psi. So according to 406.4.1, the correct test pressure should be "not less than 3 psig." Agreed?

There is an Ansul gas valve in the piping that states on the label, "Max pressure 10 psi." So I precharged the gas piping to 10 psi for the inspection. The inspector refused to pass our gas piping, stating that "All low-pressure gas line tests must be performed at 20 psi." When I pointed out the limitation on the Ansul valve, he told me to remove it from the piping and bypass it for the test, then reinstall it after and bubble test it for leaks.

I contacted Ansul tech support and the engineer confirmed that we should not test above 10 psi with their valve in the line. He also agreed that testing at 10 psi would be far greater than necessary since that's over 20 times the service pressure.

I'd rather not get into a pissing match with the inspector, especially since I already (mildly) objected to the 20 psi test and he emphatically stated that it was required. (I knew the IFC did not require a 20 psi test, but I was not expecting this from him so I didn't have the code reference ready to challenge him). On the other hand, I do not wish to have our (perfectly assembled and pressure-tested) piping disassembled to meet his arbitrary 20 psi test requirement.

I'm curious what other inspectors require for gas piping pressure tests. I'd also like recommendations on how to proceed. Thanks.
 
Our gas supplier also operates at a .5 psi however they require a pressure test of 10 psi for 15 minutes so that is what we look for.
 
For what it's worth, my piping has held 10 psi for the past few weeks. Exactly without any deviation.

Before the Ansul valve was installed, I had tested the gas pipe in sections as it was being put together and tested it at 20 psi because, why not? The pipe can clearly handle much higher pressures, but my test gauge maxes out at 30 psi (and one should never peg a gauge at its max value). The Ansul valve was installed last. Once that went into the system, I limited the final pressure test to 10 psi per the label on the valve.

In any case, I'm curious: what codebook requires the 10 psi test? Does anyone here operate under the IFC and do you agree that it only requires a test pressure of no less than 3 psi?
 
Also from the Fuel Gas Code, unamended;

406.4.1 Test pressure. The test pressure to be used shall
be not less than 11/2 times the proposed maximum working
pressure, but not less than 3 psig (20 kPa gauge), irrespective
of design pressure. Where the test pressure exceeds
125 psig (862 kPa gauge), the test pressure shall not
exceed a value that produces a hoop stress in the piping
greater than 50 percent of the specified minimum yield
strength of the pipe.

We chose to stay with the 10 psi from the Uniform Code days.
 
Cold temps will effect the gauge if left on overnight in an unheated environment.

IFGC107.3 Testing
IFGC 406.1 and 406.4.2
 
Michael.L said:
For what it's worth, my piping has held 10 psi for the past few weeks. Exactly without any deviation.


In any case, I'm curious: what codebook requires the 10 psi test?
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I have witnessed fluctuations in the test pressure due to the ambient temp changing from early morning to late afternoon.

The code that I have which states 10 psi for 15 minutes is the 2020 California Plumbing Code which is based on the 2018 Uniform Plumbing Code.

A word to the wise.....I always release some pressure to verify that the gauge is not stuck. I used to be looking for a sulfur smell and then one day the gauge was stuck. I had one case where a 100 psi gauge was maxed out and a new furnace was not isolated. I contacted the furnace manufacturer and was advised that if the furnace still operates it is not damaged.
 
I am well aware of the effects of thermal expansion/contraction. There is not a significant change when the gauge is observed from day-to-day because the temps are fairly consistent from day-to-day at the times the gauge is observed.

My gauge is not stuck. I can tap the gauge and the needle bounces. I can slowly let the air out and watch the gauge needle gradually drop. I can re-pressureize and watch the needle slowly rise.

The pipe is holding 10 psi. It has been for weeks. It was holding 20 psi before the Ansul valve was installed. The integrity of the pipeline and the accuracy of the gauge are not the issues. The issue is the seemingly arbitrary requirement from the inspector that he wants to see 20 psi on the gauge in order for me to pass the inspection.
 
ICE said:
I had one case where a 100 psi gauge was maxed out and a new furnace was not isolated.
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I should have mentioned that NO gas appliances are currently connected to the gas piping. I could easily test at 100 psi if not for the Ansul valve.
 
ICE said:
You do not have to do that.
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That's my belief also. However, when I objected he insisted that all low-pressure gas piping must be tested at 20 psi.

I guess on my next inspection I'm going to have to challenge him to provide me a code reference for the basis of his demand. Unfortunately, he's a new guy (and fairly young) and he seems to be trying to flex his muscles. For example, he pulled out a tape measure and started measuring the wires in the junction boxes. Then he complained that they were "just a little longer than 6 inches." NEC only requires 6 inches.
 
Michael.L said:
That's my belief also. However, when I objected he insisted that all low-pressure gas piping must be tested at 20 psi.

I guess on my next inspection I'm going to have to challenge him to provide me a code reference for the basis of his demand. Unfortunately, he's a new guy (and fairly young) and he seems to be trying to flex his muscles. For example, he pulled out a tape measure and started measuring the wires in the junction boxes. Then he complained that they were "just a little longer than 6 inches." NEC only requires 6 inches.
Click to expand...

Sounds like you need to gently educate him,

Ask for the code section, but also have copies of the code, to show him your side.
 
Ask the building official if he can explain the difference between what the code requires and what the inspector requires. This will tell you how far the rot extends. hopefully the building official will educate the inspector.

By only requiring a bubble test for the valve I would be concerned that one of the most likely sources of leaks, the valve, would not be subject to the higher pressure test.

Explain to your client that you are complying with the code but the building inspector wants more and to do what the inspector wants will require more work to disassemble and reassemble part of the plumbing and as a result you will be sending him a bill for the additional work. You may then suggest that your client talk to his city council member.
 
I checked Boulder County Amendments, and found nothing in the amendments that support a 20psi test.

He has no written code support, take it to his supervisor, or if you have the time, their Board of Appeals.
 
We have a city ordinance to test at 20 psi for 15 minutes, but I think we are fairly unusual in that regard. In any case like yours, we would definitely allow a 10 psi test as an exception, if a higher test would damage the portions of the gas line. As you say, the code would definitely allow a 10 psi test, and especially if you had 20 psi on the other parts of the line like you said.

Gotta be reasonable...
 
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