Natural Gas Distribution Line Leak
A natural gas distribution line leaked and gas
migrated into a nearby construction site. The
migrated gas accumulated inside a newly installed
sewer pipe. When the gas concentration in the sewer
pipe reached out the Lower Explosive Limit (LEL),
the natural gas in the sewer pipe ignited and
exploded.
Pressure testing of the gas line revealed a
perforation in the gas distribution line. The
leaking gas line is shown in Photograph A. A white
arrow denotes the pipeline leak.
Photograph A:
Close-up view of gas/water leak discovered during
leak test.
Visual examination of the natural gas distribution
line revealed a through wall, round bottomed
corrosion pit.
The corrosion penetrated along what visually
appeared to be a ferrite weld line along the gas
line ERW butt weld. A close-up view of the ferrite
weld line failure is shown in Photograph B below.
Photograph B:
Close-up view of corrosive attack along weld ferrite
line in
ERW butt welded gas pipe
Long-term degradation of the asphaltic coating, used
to protect the steel pipeline from corrosion
occurred, thereby allowing corrosion to proceed
along the steel gas distribution line. The failure
of their gas distribution line was believed to be
the result of lack of maintenance by the gas utility
owning the distribution line.
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Dr.
R. Craig Jerner, Ph.D., PE specializes in accident
investigation and metallurgical failure analysis,
with over 30 years experience as a metallurgical consultant and accident investigator. He has testified as a metallurgical expert in over 250
depositions and more than 70 court appearances. If you or someone you know should need the services of Dr. Jerner and J.E.I. Metallurgical, please visit our web site at the buttons below, or e-mail Dr. Jerner --- 