TPT September 2012

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September 2012 75
Technology News
C O N T R O L B Y M E A S U R E M E N T
Laser and inspection systems for
true dimensional measurement
TubeProfilerTM
Mill Gauge
• Real time profile measurement
• Diameter, ovality, straightness, length
• Full cross section shape with no blind spots
• Faster mill set up
• Applications:
Hot or cold Tube & Pipes,
round, square, rectangular
True Profiles Effective support
for longevity
of pipes
PROTECTIVE and resistant coatings applied during pipe
manufacture, as well as manually on-site, are the tools of
choice for reducing damage caused by corrosion. These
thin shields against mechanical and chemical attacks need
support by a careful and professional check for cracks,
pores or other damage.
A check of the protective coating by means of high voltage
impulses can provide the certainty that unprotected spots,
which are consequently targets for corrosion, are detected
no matter how small. A reliable method needs to be able
to find material defects such as pores and cracks; other
mechanical damage; and the results of handling errors in
applying the coating material.
The testing of coverings and coatings with NDT devices
that make use of pulse-type high voltage technology has
been introduced worldwide due to its many advantages.
Isotest® equipment based on this technology supplies the
required safety margin, and can maintain the chosen testing
voltage even when facing rough conditions and growing
pipe diameters.
Two major components are important in this context:
the built-in sphere gap, which stabilises high voltage
permanently; and powerful and automatic regulation of the
test voltage, which guarantees that even under demanding
test conditions, such as moisture on the surface, the voltage
is adjusted to the set value in a fraction of a second.
If the pipe is still lying or hanging freely, a spiral electrode
can perform an all-embracing job, and the test can be done
in a single step, around the complete circumference of
the pipe. This is also the easiest and quickest way to test
longer sections of pipe. If the pipe has already been laid in
the trench, a half-round brush is a suitable alternative. This
is the easiest and quickest method when there is a longer
section ahead.
In addition to electrodes for the testing of the outer
circumference, which generally involves the more robust
type of coating, there are various types for thin or delicate
coatings. In these cases the metal brush set is replaced by
a special type of conductive rubber. A further alternative may
be an electrode for the testing of the inside of the pipes,
combining stainless steel and nylon bristles.
The use of a grounding sleeve has proved its worth in
cases where a conductive connection to the test object
cannot be reached. It is also recommended to use a
grounding sleeve on poorly conductive or extremely dry
ground. The grounding sleeve consists of a special type
of conductive rubber and represents a form of capacitive
grounding that can only be achieved by using pulse-type
testing technology.
Elmed Dr Ing Mense GmbH – Germany
Fax: +49 2056 93 2933
Email:
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