the design, fabrication, installation, inspection,
testing and safety aspects of operation and
maintenance of gas transmission and distribution
systems, including gas pipelines, gas compressor
stations, gas metering and regulation stations, gas
mains, and service lines up to the outlet of the
customer's meter set assembly....802.14 This code
does not apply to....(c) piping beyond the outlet
of the customers meter set assembly..."
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Use test pressure of 1 1/2 times maximum working pressure, but in no case
less than 350 kPa (gage) 50 psig. Do not test until every joint has set
and cooled at least 8 hours at temperatures above 10 degrees C 50 degrees F.
Conduct testing before backfilling; however, place sufficient backfill
material between fittings to hold pipe in place during tests. Test system
gas tight in accordance with [NFPA 54] [or] [ASME B31.8]. Use clean dry
air or inert gas, such as nitrogen or carbon dioxide, for testing. Systems
which may be contaminated by gas shall first be purged as specified. Make
tests on entire system or on sections that can be isolated by valves.
After pressurization, isolate entire piping system from sources of air
during test period. Maintain test pressure for at least 8 hours between
times of first and last reading of pressure and temperature. Take first
reading at least one hour after test pressure has been applied. Do not
take test readings during rapid weather changes. Provide temperature same
as actual trench conditions. There shall be no reduction in the applied
test pressure other than that due to a change in ambient temperature.
Allow for ambient temperature change in accordance with the relationship PF
+ 101.32 = (P1 + 101.32) (T2 + 273) / T1 + 273) PF + 14.7 = (P1 + 14.7) (T2
+ 460) / T1 + 460), in which "T" and "PF" represent Centigrade Fahrenheit
temperature and gage pressure, respectively, subscripts "1" and "2" denote
initial and final readings, and "PF" is the calculated final pressure. If
"PF" exceeds the measured final pressure (final gage reading) by 3 1/2 kPa
1/2 psi or more, isolate sections of the piping system, retest each section
individually, and apply a solution of warm soapy water to joints of each
section for which a reduction in pressure occurs after allowing for ambient
temperature change. Repair leaking joints and repeat test until no
reduction in pressure occurs. In performing tests, use a test gage
calibrated in 7 kPa one psi increments and readable to 3 1/2 kPa 1/2 psi.
3.2.4
System Purging
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NOTE: To assist the designer in selecting the
proper documents for a specific project, the
following scope in accordance with documents is
provided:
1. NFPA 54 Scope: "1.1.1 Applicability: ...
Coverage of piping systems extends from the point of
delivery to the connections with each gas
utilization device. For other than indicated
liquified petroleum gas systems, the point of
delivery is the outlet of the service meter
assembly, or the outlet of the service regulator or
service shutoff valve when no gas meter is provided.
For undiluted liquified petroleum gas systems, the
point of delivery is the outlet of the first stage
SECTION 15195N
Page 19
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