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Staff opinion: Mechanical

Inquiry:

06-01

Subject:

Gas pipe pressure testing

Code Reference:

Chapter 1346, Minnesota Fuel Gas Code

Submitted By:

Jeff Pleski
Building Inspector

Approved By:

Andy Thielen
Construction Codes and Licensing Division, Mechanical Engineer

Issue Date:

October 16, 2006

Question:

What is the proper testing method for natural gas piping? What medium should the piping be filled with during the test?

Answer:

The following opinion is based on the 2000 International Fuel Gas Code (IFGC) that has been amended and adopted as Chapter 1346, Minnesota Fuel Gas Code.

Paragraph 406.4 (IFGC) Test pressure measurement indicates that a manometer OR a "pressure measuring device" is to be used for the test. The Code does not require the use of a manometer.

IFGC Paragraph 406.4.1 "Test pressure" (amended) and paragraph IFGC 406.4.2 "Test duration" (amended) outline the testing requirements for a fuel gas system; usually, this is a "minimum of 25 psig (172 kPa gauge) for 30 minutes." The test time can be shortened to "10 minutes in a single-family dwelling with prior approval from the Building Official."

A "pressure measuring device" includes equipment such as a "digital manometer," pressure gage, magnehelic gage and others. The device used should have sufficient accuracy to detect any leaks that may occur in a gas piping system. The minimum requirements for a pressure measuring device are outlined in paragraph 1346.5406.4.3 "Test gauges" (amended) of the Minnesota Mechanical Code.

For the above tests paragraph 406.2 (IFGC) Test medium states that the test medium for testing a fuel gas system to be "air or other inert gas."

IFGC paragraph 406.6" Piping system, appliance and equipment leakage check" requires a second separate test when the appliance is installed.

Comments:

The IFGC is clear in on the testing requirements for gas piping. It indicates that a manometer OR a "pressure measuring device" is to be used for the test. It does not require the use of a manometer.

Liquid filled manometers are no longer in common use. For safety reasons, they are not typically be used to test fuel gas systems. However, the mention of a manometer in the IFGC does imply a degree of accuracy that is not always found in other "pressure measuring devices."

After the piping system has been tested in accordance with the IFGC paragraph 406.4, IFGC paragraph 406.6 "Piping system, appliance and equipment leakage check" requires a second separate test when the appliance is installed. This paragraph shall be followed for the installation of new appliances and when existing appliances are replaced. In general this paragraph allows the use of natural gas as the test gas and lists several common testing methods to detect leaks.

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