TPT March 2007

102 / 116

Inspection, Measuring, Testing & Marking
100 March/April 2007
Now, more than ever, the inspection
process is being included as a part of
production rather than an added service.
The end result is that mills provide pipe
inspected to API (American Petroleum
Institute) or ISO (International Standards
Organization) published standards before
shipping.
These pipe producers are investing
millions of dollars in a variety of inspection
techniques such as UT (ultrasonic testing),
EMI (electromagnetic inspection), and EC
(eddy current). Speed and accuracy are
the important qualifications for the test
equipment.
The common
element in the three
methods is the
need to calibrate
the inspection
equipment. A
requirement in the
calibration process
is nearly always the
use of a calibration
specimen. Also
referred to as test
blocks, cal blocks,
coupons, and cal
standards, the
specimen is a
sample of the same
(or near same)
metal as that being
inspected.
The specimen has one or more artificial
flaws introduced into it. These flaws are
as simple as a hole or can be an intricate
series of notches on both the inside
diameter and outside diameter of the pipe.
The specimen can be as small as a few
inches of pipe cut from the production run
to a full length pipe.
The process that meets the requirements
to make the artificial flaws is known as
EDM (electric discharge machining), while
the process is also referred to as metal
erosion.
Scan Systems Corporation (USA) has been
making calibration standards for over 20
years. The company creates the standards
at its Houston, Texas facility with EDM or
conventional machining, and ships material
worldwide.
In addition, the company manufactures and
market the EDM Notch Master used in pipe
mills, the same unit used at its own facility.
Scan Systems – USA
Fax: +1 281 219 2317
Email:
Website:
Calibration specimens vital to all inspection processes
fi A calibration specimen is used in all three main inspection techniques