StressTel T-MIKE ES User manual
T-MIKE ES
OPERATION
MANUAL
021-002-090
T-MIKE ES
OPERATION
MANUAL
Version 2.1
July 2005
Revision D
¤2005 GE Inspection Techonologies
50 Industrial Park Road
Lewistown, PA 17044
Phone (717) 242-0327 Fax (717) 242-2606
www.geinspectiontechnologies.com
Table of Contents
Important Notice............................................................................................................................................1
Thoeory of Operation.................................................................. ...................................................................5
Diagram of a System.................................................................. ...................................................................7
Specifications............................................................................. ...................................................................9
Initial Setup...................................................................................................................................................11
Operation......................................................................................................................................................15
T-Mike Programmable.....................................................................................................................................25
Helpful Hints on Operation...............................................................................................................................27
Maintenance and Troubleshooting............................................................................................................. ......29
Warranty and Service......................................................................................................................................31
Appendix A....................................................................................................................................................35
Appendix B.....................................................................................................................................................37
IMPORTANT NOTICE
The following information must be read and understood by any user of a GE Inspection Technologies ultrasonic thickness gauge.
Failure to follow these instructions can lead to errors in thickness measurements or other test results. Decisions based on erroneous results
can, in turn, lead to property damage, personal injury or death.
General Warnings
Proper use of ultrasonic test equipment requires three essential elements:
. Selection of the correct test equipment
. Knowledge of the specific “test application requirements”
. Training on the part of the instrument operator
This operating manual provides instruction in the basic set-up and operation of the GE Inspection Technologies thickness gauge. There are,
however, additional factors that affect the use of the ultrasonic test equipment. Specific information regarding these additional factors is
beyond the scope of this manual. The operator should refer to text books on the subject of ultrasonic testing for more detailed information.
Operator Training
Operators must receive adequate training before using ultrasonic test equipment. Operators must be trained in general ultrasonic testing
procedures and in the set-up and performance required by a particular test. Operators must understand:
. Sound wave propagation theory
. Effects of the velocity of the test material
.Behavior of the sound wave where two different materials
are in contact
.Areas covered by the sound beam
More specific information about operator training, qualification, certification and test specifications is available from various
technical societies, industry groups, and government agencies.
Testing Limitations
In ultrasonic testing, information is obtained only from within the limits of the sound beam. Operators must exercise great
caution in making inferences about the test material outside the limits of the sound beam. Testing large materials may make
inspection of the entire test piece impracticable or impossible. When a less-than-complete inspection is to be performed, the
operator must be shown the specific areas to inspect. Inferences about the condition of areas not inspected, based on data
from the evaluated areas, should only be attempted by personnel fully trained in applicable statistical and probability tech-
niques. In particular, materials subjects to corrosion or erosion, in which conditions can vary significantly in any given area,
should be evaluated only by fully trained and experience operators.
Sound beams reflect from the first interior surface encountered. Because of part geometry and overlapped flaws or overlapped
surface, thickness gauges may measure the distance to an internal flaw rather than to the back wall of the material. Operators
must take steps to ensure that the entire thickness of the test material is being examined.
Ultrasonic Thickness Measurement Critical Operating Procedure
The following operating procedures must be observed by all users of ultrasonic thickness gauges in order to minimize errors in
test results.
3. Effects of Temperature on Calibration
Variations in temperature change the sound velocity of materials and transducer delay lines and therefore, zero calibration. All
calibrations should be performed on-site and with test blocks at the same temperature as the test piece, in order to minimize
errors due to temperature variations.
1. Calibration of Sound Velocity
The principle of operation of an ultrasonic thickness gauge is that the instrument measures the time of flight of an ultrasonic
pulse through the test piece and multiplies this time by the velocity of sound in the material. Thickness measuring error is
minimized by ensuring that the sound velocity to which the instrument is calibrated is the sound velocity of the material being
tested. Actual sound velocity in materials often varies significantly from the values found in published tables. In all cases, best
results are obtained if the instrument is calibrated on a velocity reference block made from the same material as the test piece.
This reference block should be flat, smooth and as thick as the maximum thickness of the test piece.
Operator should also be aware that sound velocity may not be constant in the material being tested; heat treating, for example,
can cause significant changes in sound velocity. This must be considered when evaluating the accuracy of the thickness
provided by this instrument. Instruments should always be calibrated before testing, and the calibration should be checked after
testing, to minimize testing errors.
2. Probe Zero Procedure
The probe zero procedure must be performed as described in this manual. The zero reference block should be clean and in good
condition, without noticeable wear. Failure to properly perform the probe zero procedure will result in inaccurate thickness
readings.
4. Transducer Selection
The transducer used in testing must be in good condition without noticeable wear of the front surface. Badly worn transducers
will have a reduced effective measuring range. The specified range of the transducer must include the complete range of
thickness to be tested. The temperature of the material to be tested must be within then transducer’s temperature range.
5. Use of Couplants
Operators must be familiar with the use of ultrasonic couplants. Testing skills must be developed so that couplant is used and
applied consistently to minimize variations in couplant layer thickness and errors in test results. Calibration and actual testing
should be performed under similar coupling conditions, using a minimum of couplant and applying consistent pressure on the
transducer.
6. Doubling
Ultrasonic thickness gauges will, under certain conditions, display readings which are twice (or in some cases, three times) the
actual material thickness being measured. This effect, commonly known as “doubling,” can occur below the minimum specified
range of the transducer. If the transducer being used is worn, doubling is possible at thickness greater that the minimum
specified range.
When using a new transducer, any reading that is less than twice the minimum specified range of the transducer may be a
“doubled” reading. The thickness of the material being tested should be verified by the use of other methods. If the transducer
shows any sign of wear, doubling may occur at thickness greater than twice the minimum specific range. This thickness should
be determined by calibrating the instrument and transducer combination on reference blocks that represent the complete range
of possible thickness that may be encountered in testing. This is particularly important when the test piece is being ultrasoni-
cally measured for the first time or in any case where the history of thickness of the specimen in unknown.
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