Issue
Date: October 13, 2006
Revision Date: July 13, 2007
Linde Services, Inc.
(Formally Praxair Services, Inc., originally listed as Tracer Research Corp.)
SeeperTraceTM
LARGE DIAMETER
LINE LEAK DETECTION METHOD (6 inches diameter or above)
Certification
|
Leak
rate of 0.1 gph with PD = >99% and PFA = <1%.
The USEPA has not set a minimum detectable leak
rate for large diameter pipeline systems (airport hydrant
systems) at the time of this evaluation.
|
Leak
Threshold
|
A
pipeline system should not be declared tight when a confirmable
level of chemical tracer in the sample collected exceeds
the background level. |
Applicability
|
Gasoline,
diesel, aviation fuel, fuel oil #4, waste oil.
Other fluids which are compatible and soluble with an
acceptable tracer chemical may be tested after consultation
with the manufacturer. |
Pipeline
Capacity
|
Not
limited by capacity.
Pipeline segments up to 1500 feet in length may be covered
by an individual test sample collected continuously along
this length. |
Waiting
Time
|
Ranges
from 1 to 6 days after tracer is added to the product
in the pipeline.
All releases at a depth of 5 feet in non-engineered backfill
were detected within 1 day after the start of the test.
All releases at a depth of 10 feet were detectable 6 days
after the start of the test.
Leak simulations conducted at the depth of the pipeline
can be used to validate test parameters such as soil permeability
and waiting period.
For very large pipeline systems, several days or weeks
may be required to circulate tracer-labeled product through
all parts of the pipeline.
Waiting time begins after the tracer has reached the portions
of the pipeline being tested. |
Leak
Simulations
|
Leak
simulations are the release of surrogate tracer into the
soil or backfill at the depth of the pipeline to evaluate
the migration of a tracer and the sensitivity of the test
under on-site sub-surface conditions. Sub-surface conditions
throughout the test area must be at least as favorable
as those at the leak simulation location in order to use
the results. |
Tracer
Dosage
|
Dosage
of tracer is based on pipe capacity and frequency and
volume of pipe use according to manufacturer's recommendations.
Tracer-labeled product must be circulated through the
pipeline before test period begins.
Pressurized pipeline must be brought up to operating pressure
or operated on a daily basis. |
System
Features |
Pipeline
must be accurately located to ensure that sampling activity
is within the zone of influence of the tracer.
Sampling is conducted using a small metal sled that is
pulled on the ground above the pipeline being tested.
|
Comments
|
The
tester may determine that pre or post testing is needed
to establish the background level of tracer in the soil.
Due to the vapors being collected at the surface, testing
can be affected by extreme windy conditions. High winds
will generally cause a reduction in the amount of tracer
from a release that is collected in the test sample.
The presence of a layer of water saturated soil, that
is also frozen, above the location where a leak may exist,
may impede the transport of the tracer labeled product
into the sampling zone.
Groundwater surrounding the pipeline may limit effectiveness
of test method (e.g. when applied to pipelines containing
water-miscible products or products whose specific gravity
is greater than 1).
Leak simulations performed at the depth of the pipeline
along sections of the pipeline below the water table or
below saturated, frozen soil allow for validation of the
method in these conditions. |