|
Pipeline
Inspection
Whether your
pipeline is onshore or offshore or if it transports
liquid or gas, CWIC inspection tools meet your
integrity program objectives. We offer pipeline
inspection for
oil pipelines,
gas pipelines
and offshore
inspection.
In the United States, millions
of miles of pipeline carrying everything from water
to crude oil. The pipe is vulnerable to attack by
internal and external corrosion, cracking, third
party damage and manufacturing flaws. If a pipeline
carrying water springs a leak bursts, it can be a
problem but it usually doesn't harm the environment.
However, if a petroleum or chemical pipeline leaks,
it can be a environmental disaster. More information
on recent US pipeline accidents can be found at the,
National Transportation Safety
Board's Internet site.
In an attempt to keep pipelines operating safely,
periodic inspections are performed to find flaws and
damage before they become cause for concern.
When
a pipeline is built, inspection personnel may use
visual, X-ray, magnetic particle, ultrasonic and
other inspection methods to evaluate the welds and
ensure that they are of high quality. The image to
the left show two NDT technicians setting up
equipment to perform an X-ray inspection of a pipe
weld. These inspections are performed as the
pipeline is being constructed so gaining access the
inspection area is not problem. In some areas like
Alaska, sections of pipeline are left above ground
like shown above, but in most areas they get buried.
Once the pipe is buried, it is undesirable to dig it
up for any reason.
So, how do you inspect a buried pipeline?
Have
you ever felt the ground move under your feet? If
you're standing in New York City, it may be the
subway train passing by. However, if you're standing
in the middle of a field in Kansas it may be a pig
passing under your feet. What??? Engineers have
developed devices, called pigs, that are sent
through the buried pipe to perform inspections and
clean the pipe. If you're standing near a pipeline,
vibrations can be felt as these pigs move through
the pipeline. The pigs are about the same diameter
of the pipe so they range in size from small to
huge. The pigs are carried through the pipe by the
flow of the liquid or gas and can travel and perform
inspections over very large distances. They may be
put into the pipe line on one end and taken out at
the other. The pigs carry a small computer to
collect, store and transmit the data for analysis.
In 1997, a pig set a world record when it completed
a continuous inspection of the Trans Alaska crude
oil pipeline, covering a distance of 1,055 km in one
run.
Pigs
use several nondestructive testing methods to
perform the inspections. Most pigs use a magnetic
flux leakage method but some also use ultrasound to
perform the inspections. The pig shown to the left
and below uses magnetic flux leakage. A strong
magnetic field is established in the pipe wall using
either magnets or by injecting electrical current
into the steel. Damaged areas of the pipe can not
support as much magnetic flux as undamaged areas so
magnetic flux leaks out of the pipe wall at the
damaged areas. An array of sensor around the
circumference of the pig detects the magnetic flux
leakage and notes the area of damage. Pigs that use
ultrasound, have an array of transducers that emits
a high frequency sound pulse perpendicular to the
pipe wall and receives echo signals from the inner
surface and the outer surface of the pipe. The tool
measures the time interval between the arrival of a
reflected echos from inner surface and outer surface
to calculate the wall thickness.
On some pipelines it is easier to use remote visual
inspection equipment to assess the condition of the
pipe. Robotic crawlers of all shapes and sizes have
been developed to navigate the pipe. The video
signal is typically fed to a truck where an operator
reviews the images and controls the robot.
Contact Us for
more information
8650 Hackberry
Lane Suite 500
Beaumont, TX 77705
(409)543-9980
|
