Innovations 27 2015

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a full picture of the pipeline’s condition and, in
many cases, convincing them that these lines can’t
even be inspected.
An Inspection Breakthrough For
Difficult-To-Pig Lines
T.D. Williamson (TDW) recognized the challenge
of controlling drag to improve wall thickness
inspections in a small diameter, low flow, low
pressure environment. And, in response, the
company developed a 6-inch low drag deformation
and MFL inspection tool that, according to TDW
integrity expert Lloyd Pirtle, not only “removes or
minimizes” speed excursions, but makes it possible to
inspect lines long thought of as too difficult to pig.
“This tool and capability creates confidence,”
Pirtle says. “Operators can now collect geometry
and metal loss data to know what kind of shape
their system is in – even with low flow or low
pressure – while these critical pipelines remain in
service.
“For operators with similar obstacles who’ve
thought their lines weren’t piggable, what we’re
saying is, ‘here’s a tool that can make it piggable,’”
he adds.
The new 6-inch tool not only overcomes the
design compromises that restricted navigability and
wall thickness inspection in conventional small-
diameter MFL tools, it also includes geometry
inspection on the same platform for improved
threat assessment versus stand-alone MFL.
Its advantages include:
• Greater wall thickness capability
• Reduced drag
• Improved navigability
• Improved protection of the magnetizer
Successful Field Testing
Following extensive internal validation using
multiple 6-inch tool configurations, the low drag
tool was field-tested* in partnership with Access
Midstream, a natural gas service provider and
subsidiary of energy company Williams. The tool
was run seven times on pipelines in Texas’s Barnett
Shale, at pressures around 10.34 bar (150 psi).
According to Chuck Harris, Manager, Strategic
Commercialization at TDW, although some speed
excursions occurred with the low drag tool, they
weren’t on the magnitude of those experienced
with traditional inspection tools. The tool gathered
acceptable inline inspection data at pressures as low
as 8.27 bar (120 psi).
“The technology cannot overcome line
conditions completely,” Harris says. “What’s
important is the fact that it can run in pipelines even
at such low pressures.”
In other words, the new low drag tool essentially
opens previously difficult-to-inspect pipelines to
easier, more accurate assessment.
Which can also open operators’ minds to the
possibility of pigging.
I N N O V AT I O N S • V O L . V I I , N O. 3 • 2 0 1 5
7
*Download the white paper from Access
Midstream and TDW to learn more:
DEF2+MFL4 Drag Results
Drag comparison was performed
between multiple 6-inch configurations:
MFL: traditional stand-alone metal loss
inspection
DEF+MFL: traditional geometry
combined with metal loss inspection
DEF2+MFL4: newly designed geometry
combined with metal loss inspection
Drive: drive body only
DRAG TESTING
55%
59%
61%
68%
Drag reduction vs MFL in 0.188-inch
Wall Thickness (WT)
Drag reduction vs DEF+MFL in 0.188-inch WT
Drag reduction vs MFL in 0.388-inch WT
Drag reduction vs DEF+MFL in 0.388-inch WT