LINE TIGHTNESS TESTING works as follows :
- The line is taken out of service and pressurized. A
drop in
pressure over time, preferably one hour, suggests a possible
leak.
- Suction lines are not pressurized very much during a
tightness test
(less than 15 pounds per square inch).
- Tightness tests must be conducted at least very 3 years.
- Most line tightness tests are preformed by a testing
company; you
just observe the test.
- Some tank tightness tests can be performed so as to
include a
tightness test of the connecting piping.
- For most tightness tests, no permanent equipment is
installed.
- Line must be taken out of service for the test, ideally
for several
hours, to allow line to stabilize before the test.
- In the event of a trapped vapor pocket, it may not be
possible to
conduct a valid tightness test. There is no way to tell
definitely
before the test begins if this will be a problem. Longer
more
complicated piping runs with many risers and dead ends are
more likely
to have vapor pockets.
LEVEL OF LEAK DETECTION REQUIRED
For suction pipe: must detect leak as small
as 0.1 g/hr
For pressurized pipe: must detect leak as
small as 0.1 g/hr when line pressure is 1.5 times its normal
operating pressure.
COST
When performed at the same time as a tank tightness test, a typical
line tightness test costs about $50 -
$100, depending on the length and complexity of the piping.