Case Study:
Mobil cuts costs substantially utilizing helium leak detection method
Problem:
Engineers at the Mobil Oil Refinery, located in Torrance, California, were looking
for a more efficient and cost effective method of checking pipelines for leaks.
The large refinery utilizes miles of pipelines, most of which were routinely tested
for leaks using tradition hydrotesting technique.
| "Although water was inexpensive, the testing process created an unwanted by-product:
contamination." |
Hydrotesting, a common method of testing for leaks, was notoriously time-consuming,
imprecise, and costly.
The major issue was the water itself. Although water was inexpensive, the testing
process created an unwanted by-product: contaminated water. After every test,
a vacuum truck removed the contaminated water and brought it to Mobil's center
for hazardous waste processing, The handling and treatment of this water was
not only expensive, it was time-consuming.
Another problem was the physical nature of water. Because water reacts to any
temperature change, it was difficult to tell during the eight-hour monitoring
of the hydrotest whether drops in pressure were the result of leakage or not.
To further complicate matters, hydrotesting was unable to pinpoint the location
of leaks. In the event of a detected leak, a crew had to physically examine the
lines and dig up underground pipes in search of leaks. Again, the hydrotesting
method proved to be costly and time-consuming.
Investigation:
Mobil Inspection Engineer, Gary Teel, explored various alternatives to the hydrotest
method. He examined testing methods using acoustic emissions and inert gases
such as sulfur-hexafloride and helium. After comparing costs and methods, Mr.
Teel recommended they do a sample test using helium gas and contacted Helium Leak
Testing, Inc. in Northridge, California.
Solution:
Monitored by two Helium Leak Testing, Inc. technicians, the helium test began
like the hydrotest. The designated line was physically "blinded" by dropping
flanges-metal plates-across parts of the line they wanted to isolate and the evacuated
line was then filled with helium pressurized at 15 psi.
| "One technician slowly walked the pipeline and carried a sniffer probe..." |
Helium, with its tiny molecular size and lighter-than-air weight, under pressure
finds "the path of least resistance" and quickly rises. In this case, that path
was a potential pipeline leak and a "sniffer" probe, when placed over the vicinity,
would be able to detect the presence of the helium.
One technician slowly walked the pipeline and carried the sniffer probe which
was attached by a long thin tube to the mass spectrometer in the van. The second
technician, driving the van, followed his partner and monitored the instruments.
As the mass spectrometer created a vacuum pull on the sniffer probe, air was pulled
in and any escaping helium was detected. If helium was detected, an electronic
alarm would sound, increasing intensity when the probe was closest to the area
where helium was flowing through the leak. In that situation, the technician
walking the line would simply mark the area of the pipeline and moved on. Since
the helium is able to rise through the ground and even asphalt, Mobil also discovered
that leaks in underground pipes could be easily detected by simply drilling several
holes into the ground which would speed up helium's escape from a leaking pipe
through the layers of dirt and asphalt.
Result:
Mobil found helium to be ideal for pipeline leak testing. The biggest benefit,
of course, is that helium does not create contaminated waste product that requires
treatment.
Mobil was also pleased with the helium's ability to eliminate guesswork. Helium
not only detects leaks, it simultaneously detects the location of leaks--even
underground.
Helium Leak Testing, Inc. demonstrated that time and manpower requirements could
be greatly reduced with the helium test method. Since only two staff members
are needed to close, evacuate, and then reopen the line, the use of an outside
vendor, like Helium Leak Testing, Inc., entirely frees up staff members from monitoring
the test and physically locating leaks.
Mr. Teel estimates that Mobil will save a tremendous amount of money due to the
new helium leak detection method. He predicts that Mobil will save in terms of
reduced manpower costs, reduced waste treatment costs, and overall reduced testing
costs. Mobil has also gained a more efficient and more accurate test method that
can be applied to many other testing areas as well.
