TPT May 2017

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T E CHNOLOG Y
MAY 2017 39
Spain: Tel: +34 665 782908
Ultrasonic rotary test system
UNICORN Automation (NDT) has
supplied ultrasonic test systems globally
for more than 20 years. It specialises in
the ability to test hot finish tubes such
as OCTG tubes using its unique contact
shoe technique.
Tubes with pronounced hooked ends
and poor straightness can be fully
tested using this technique without
any compromise to the test. Testing
with contact shoes offers repeatability
at the fast production speeds required
by modern tube mills or third-party
inspectors.
To satisfy a growing requirement to
test ever smaller diameters – tubing
in the OCTG field, Unicorn have
developed their contact shoe technique
to test tubes down to the 25mm od size.
The rotary head designated URP200/S
now has the capability to test tubes with
a diameter range 25mm to 220mm. The
test head can be equipped with up to
30 transducers carrying out inspection
for longitudinal, transverse, oblique
and lamination/wall thickness defects.
The test systems can cope with off-
centre tubes and the unique contact
shoe raise/lower system allows the
free passage of upset ends or threaded
tube ends. With a maximum rotation
speed of 700RPM test speeds of up to
40m/min are achievable.
Prior to extending the range of the
URP200/S Unicorn could only offer
the testing of tubes in the 25 to 48mm
diameter range by means of a water
chamber head. While these heads work
well on tubes with a good surface finish
and relatively small diameter variations,
they have significant drawbacks when
testing hot finished seamless tube with
poor straightness, ovality, surface scale
and upset ends.
The main problem with water
chamber heads when testing hot-
finished seamless tubes is the need for
relatively large radial guide clearances,
which allow the tube to wander off-
centre, leading to large signal variations
and inconsistent test results. It is
impractical to accommodate upset ends
by further increasing the radial guide
clearances. A further problem can be
that scale from the hot-finished product
can build up in the water chamber and
affect ultrasonic transmission. The
extended range URP200/S resolves
these issues by making the Unicorn
contact shoe technology available for
testing tubes in the (extended) 25 to
48mm diameter range.
The alternative technique of rotating or
spiraling a tube using a travelling or fixed
carriage containing the transducers,
although better than the water chamber
from a signal repeatability point of view,
has the drawback of being a relatively
slow method of testing unless numerous
transducers are employed; speed of
tube rotation is also limited further when
testing bent tubes.
Unicorn Automation (NDT) – UK
Email:
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