All sealed systems leak. The leak could be at 1-lb. per second
or as slow as 1-oz. every million years.
Every pressure system has leaks because "flaws" exist
at every joint fitting, seam or weld. These "flaws" may
be too small to detect even with the best of leak detection
instruments. But given time, vibration, temperature and
environmental stress, these "flaws" become larger,
detectable leaks.
A LEAK IS NOT...Some
arbitrary reading on a meter. Gas escapes at different times and
at different rates. In fact, some leaks cannot be detected at the
time of the test. Leaks may plug, then re-open under peculiar
conditions.
A LEAK IS...A physical path
or hole, usually of irregular dimensions. The leak may be the
tail end of a weld fracture, a speck of dirt on a gasket or a
microgroove between fittings.
 |
 |
An electron micrograph of a "clean" silver soldered joint. Note the crack lines and other impurities of the melted metal. |
Further
magnification shows actual metal separation. |
It is incorrect to
state that a unit has "no leaks." All equipment
has leakage to some degree. |
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