Each building within 300 feet of the test section should be empty of
people.
The test section should be watched by a patrol during the test.
The people running the test should be in constant contact with the
patrol.
The fuel used should be a low grade, noncritical fuel that does not
vaporize quickly.
Compressed Air.
If the test section is in an area with many people, the
line should be tested with compressed air. Compressed air should also be
used to test a section of line that crosses a river. Compressed air can
only be used on clean, vapor free lines. To test coupled and welded
pipelines with compressed air, ensure that personnel:
Divide the pipeline into smaller sections than those used in testing
with fuel or water. Consider the size of the pipe and air compressor
before deciding how long of a section should be tested. Do not try to
test more than 5 miles at a time. Use the gate valves placed 1 mile
apart in the pipeline to break the test section into 1 mile pieces.
If the pipeline must be tested quickly test the line mile by mile
instead of by 5 mile sections. Break the line at each gate valve.
Uncouple and move the air compressor forward for each test. This
method cuts down on the time it takes to empty a line of air.
Uncouple the beginning of the test section from the rest of the
pipeline.
Cap off this section with a coupling made from a blank end. (To make
this coupling, cut a hole in a blank end and weld an air hose coupling
to the blank end over the hole.)
Attach the air line from the air compressor to the blank end.
Close the gate valve at the end of the first mile of test section.
Pressurize the line at 90 pounds per square inch to the closed gate
valve.
bubbles caused by air escaping at a leak. Listen for the hissing
sound of air escaping.
If a leak must be repaired: close the gate valve at the end of the
next mile of the test section, open the gate valve at the end of the
first mile to relieve pressure, repair the leak, close the gate valve
at the end of the first mile, pressurize the first mile of pipeline,
and patrol again to look and listen for leaks.
If the first mile checks out all right, close the gate valve at the
end of the second mile of the test section and open the gate valve at
the end of the first mile.
Pressurize the first 2 miles of pipeline.
Patrol for leaks in the second mile.
If there are leaks: close the gate valve at the end of the first mile
of pipeline to prevent loss of air pressure, open the gate valve at
the end of the second mile to relieve pressure in the section to be
repaired, repair leaks, close the gate valve at the end of the second
mile, open the gate valve at the end of the first mile, pressurize the
first 2 miles of the pipeline, and patrol again to look and listen for
leaks.
12-108
QM 5099
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