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Nondestructive testing is common in
the bridge inspection industry

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for testing critical bridge
components.

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Modern bridges are primarily
constructed

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from a combination of steel
and concrete.

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Steel bridge supports
are joined together

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by welded or bolted connections.

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Bridge components can
fail for several reasons,

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including corrosion, fatigue cracking,

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and weld discontinuities.

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Inspectors use a variety
of nondestructive

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techniques to monitor
bridges for defects.

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These techiniques include
using conventional ultrasound

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and phased array technology

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to inspect hanger pins,

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structural welds, beams,
and anchor bolts.

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Bridge hanger pin and plate assemblies

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are used to connect a
suspended bridge span

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to an anchored bridge span.

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The pin and plate assemblies
are critical components

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because they bear the full weight

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of the suspended bridge span.

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Cracking in hanger pins
typically occurs

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near the shear planes,

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where the bridge spans meet.

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Other pin defects include grooves

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caused by wear-related bearing forces

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and pitting caused by corrosion
near the pin surface.

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Low angle longitudinal
wave transducers

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are typically used for
conventional UT inspections

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of hanger pins.

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The low angle enhances reflections

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from outside diameter cracks,

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increases sensitivity to pitting
and other defects,

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and improves coverage of
the critical defect locations.

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Inspecting a hanger pin with

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an EPOCH 650 ultrasonic flaw detector

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requires 100% coverage
of both pin faces

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to help ensure coverage
of critical defect locations.

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However, with an OmniScan
phased array flaw detector,

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operators can create
multiple beam groups

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performed multiple times per second

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to inspect different areas
of the test piece in one pass.

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Group 1 covers the near
side threaded area

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with a refracted longitudinal
wave.

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Group 2 is a shallow angle
refracted longitudinal wave

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that covers the shear plane.

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Group 3 is a zero degree
longitudinal wave

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with induced beam spread

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used to detect large
cracks and monitor for

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backwall dropout
to help ensure coupling.

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When using either an OmniScan SX

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or MX2 phased array flaw detector

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to inspect a hanger pin,

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the group coverage eliminates
the need for rastering

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and enables encoded scanning.

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Encoded scanning systems provide

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a permanent record for reporting

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and monitoring defects.

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Phased array encoding

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also provides a geometrically correct

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representation of the scan data,

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giving the user greater confidence

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when locating and sizing defects.