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I N N O V AT I O N S • V O L . V I I , N O. 3 • 2 0 1 5
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T E C H N O L O G Y F O C U S
Every day, there’s another example of technology making
the impossible possible.
But making the difficult-to-pig easier-to-inspect?
That’s an entirely new triumph.
For natural gas operators, inspecting geometry and wall-loss in
small diameter gathering lines, especially in low flow, low pressure
environments, has been a challenge. So much so, in fact, that many
operators have their minds made up: it just can’t be done.
Now, however, there’s a new 6-inch inspection tool that overcomes
problems of size, flow, and pressure in these difficult pipelines.
Not only does it gather data for integrity assessments, it might just
change how operators view the possibility of pigging.
Avoiding Turbulence
An inline tool moves when pressure differentials around it are greater
than the friction produced by the tool itself. In the case of inspection
tools used to survey geometry and measure metal loss, progress through
pipelines is generally slow and steady. Accurate data is captured at
regular points along the line, creating a successful integrity assessment.
But during the inspection of small diameter, low flow, low pressure
pipelines, certain magnetic flux leakage (MFL) tool components – such
as urethane cups and brushes – make contact with the pipe’s interior.
This can create significant drag, which is additional frictional pressure
within the line. And drag can make an inline inspection (ILI) tool’s ride
turbulent, impairing its performance in compressible products such as
natural gas.
For one thing, drag can cause speed excursions, where the tool
accelerates abruptly and lurches ahead before returning to its normal
pace. Unless it stops completely. A standstill could last 10 seconds or
10 hours – sometimes even longer – and might eventually require an
intrusive intervention like having to cut out the MFL tool or launch a
foam pig from behind to push it along.
Drag-related speed excursions, which can be greatly exaggerated in
low pressure and low flow natural gas pipelines, prevent the ILI tool
from capturing data at every point – keeping operators from getting
Turning
Impossible
into Piggable
New 6-inch, low drag
inspection tool changes
how operators think about
assessing low flow, low
pressure lines