The USM 36 has been designed and tested according
to DIN
EN 61010-1: 2011-07, Safety requirements for
electrical equipment for measurement, control and lab
oratory use, and was technically in perfectly safe and
faultless condition when leaving the manufacturing
works.
In order to maintain this condition and to ensure a safe
operation, you should always read the following safety
information carefully before putting the instrument into
operation.
The USM 36 is an instrument for materials
testing. Any use for medical or any other
applications is not permitted!
The instrument may only be used in industrial environments.
The USM 36 is waterproof according to IP66. It can be
operated either with the corresponding lithium-ion bat
teries or with the charger/power adaptor. The charger/
power adaptor meets the requirements of electrical
safety class II.
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Battery operation
For the battery operation of the USM 36, we recommend the corresponding lithium-ion battery. You should
only use this battery for the battery operation.
You can charge the lithium-ion battery either within the
instrument itself or in an external charger. If a lithium-ion
battery is inserted, charging starts automatically as
soon as you connect the charger/power adaptor to the
USM
36 and to the mains power supply.
For power supply, please also see Chapter 3.2 Power supply, page 3-2. For the use of batteries, please also
see Chapter 7.2 Battery care, page 7-2.
Software
According to the current state of the art, software is never completely free from errors. Before using any software-controlled test equipment, it is therefore necessary to make sure that the required functions operate
perfectly in the intended combination.
If you have any questions about the use of your test
equipment, please contact your nearest GE representa
tive.
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1-2Issue 2 (12/2013)USM 36
Safety information1 Introduction
Defects/errors and exceptional stresses
If you have reason to believe that a safe operation of
your USM
nect the instrument and secure it against unintentional
re-connection. Remove the lithium-ion battery.
A safe operation is no longer possible for example
● if the instrument shows visible damages,
● if the instrument no longer operates perfectly,
● after prolonged storage under adverse conditions
(e.g. exceptional temperatures or especially high air
humidity, or corrosive environmental conditions),
● after being subjected to heavy stresses during transportation.
36 is no longer possible, you have to discon-
FCC compliance
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:
1This device may not cause harmful interference.
2This device must accept any interference received,
including interference that may cause undesired
operation.
This equipment has been tested and found to comply
with the limits for a Class A digital device, pursuant to
Part 15 of the FCC Rules. These limits are designed to
provide reasonable protection against harmful interfer
ence when the equipment is operated in a commercial
environment.
This equipment generates, uses, and can radiate radio
frequency energy and, if not installed and used in accor
dance with the instruction manual, may cause harmful
interference to radio communications.
Operation of this equipment in a residential area is likely
to cause harmful interference, in which case the user
will be required to correct the interference at his own ex
pense.
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USM 36Issue 2 (12/2013)1-3
1 IntroductionImportant information on ultrasonic testing
1.2Important information on
ultrasonic testing
Please read the following information before using your
USM
36. It is important that you understand and observe this information to avoid any operator errors that
might lead to false test results. Such false test results
could result in personal injuries or property damages.
Prerequisites for testing with ultrasonic
test equipment
This operating manual contains essential information on
how to operate your test equipment. In addition, there
are a number of factors that affect the test results, but a
description of all these factors goes beyond the scope
of this operating manual. The three most important pre
requisites for a safe and reliable ultrasonic inspection
are:
● Operator training
● Knowledge of special technical test requirements and
limits
Operator training
The operation of an ultrasonic test device requires proper training in ultrasonic test methods.
Proper training comprises for example adequate knowledge of:
● the theory of sound propagation,
● the effects of sound velocity in the test material,
● the behavior of the sound wave at interfaces between
different materials,
● the propagation of the sound beam,
● the influence of sound attenuation in the test object
and the influence of surface quality of the test object.
Lack of such knowledge could lead to false test results
with unforeseeable consequences. You can contact for
example NDT societies or organizations in your country
(DGZfP in Germany; ASNT in the USA), or also GE, for
information on the existing opportunities for training of
ultrasonic inspectors as well as on the qualifications and
certificates that can finally be obtained.
● Choice of appropriate test equipment
1-4Issue 2 (12/2013)USM 36
Important information on ultrasonic testing1 Introduction
Technical test requirements
Every ultrasonic test is subject to specific technical test
requirements. The most important ones are:
● the definition of the scope of inspection
● the choice of the appropriate test method
● the consideration of material properties
● the determination of limits for recording and evalua-
tion.
It is the task of the those with overall responsibility for
testing to ensure that the inspector is fully informed
about these requirements. The best basis for such infor
mation is experience with identical test objects. It is also
essential that the relevant test specifications be clearly
and completely understood by the inspector.
GE regularly holds specialized training courses in the
field of ultrasonic testing. The scheduled dates for these
courses will be given to you on request.
Limits of testing
The information obtained from ultrasonic tests only refers to those parts of the test object which are covered
by the sound beam of the probe used.
Any conclusions from the tested parts to be applied to
the untested parts of the test object should be made with
extreme caution.
Such conclusions are generally only possible in cases
where extensive experience and proven methods of sta
tistical data acquisition are available.
The sound beam can be completely reflected from
boundary surfaces within the test object so that flaws
and reflection points lying deeper remain undetected. It
is therefore important to make sure that all areas to be
tested in the test object are covered by the sound beam.
Ultrasonic wall thickness measurement
All ultrasonic wall thickness measurements are based
on a time-of-flight measurement. Accurate measure
ment results require a constant sound velocity in the test
object. In test objects made of steel, even with varying
alloying constituents, this condition is mostly fulfilled.
The variation of sound velocity is so slight that it is only
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USM 36Issue 2 (12/2013)1-5
1 IntroductionImportant information on ultrasonic testing
of importance for high-precision measurements. In other materials, e.g. nonferrous metals or plastics, the
sound velocity variations may be even larger and thus
affect the measuring accuracy.
Effect of the test object material
If the material of the test object is not homogeneous, the
sound waves may propagate at different velocities in dif
ferent parts of the test object. An average sound velocity
should then be taken into account for the range calibra
tion. This is achieved by using a reference block with a
sound velocity equal to the average sound velocity of
the test object.
If substantial sound velocity variations are expected,
then the instrument calibration should be adjusted to the
actual sound velocity values at shorter time intervals.
Failure to do so may lead to false thickness readings.
Effect of temperature variations
The sound velocity within the test object also varies as
a function of the material's temperature. This can cause
appreciable errors in measurements if the instrument
has been calibrated on a cold reference block, whereas
the measurement is carried out on a warm test object.
Such measurement errors can be avoided either by ad
justing the temperature of the reference block used for
calibration or by taking the temperature effect into con
sideration on the basis of a correction factor obtained
from published tables.
Measurement of remaining wall thickness
The measurement of the remaining wall thickness on
plant components, e.g. pipes, tanks, and reaction ves
sels of all types which are corroded or eroded from the
inside, requires a perfectly suitable gauge and special
care in handling the probe.
The inspectors should always be informed about the
corresponding nominal wall thicknesses and the likely
amount of wall thickness losses.
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1-6Issue 2 (12/2013)USM 36
Important information on ultrasonic testing1 Introduction
Ultrasonic evaluation of flaws
In present-day test practice, there are basically two different methods of flaw evaluation:
If the diameter of the sound beam is smaller than the extent of the flaw, then the sound beam can be used to explore the boundaries of the flaw and thus determine its
area.
If, however, the diameter of the sound beam is larger
that the extent of the flaw, the maximum echo indication
from the flaw must be compared with the maximum
echo indication from an artificial flaw provided for com
parison purposes.
Flaw boundary method
The smaller the diameter of the probe's sound beam,
the more accurately the boundaries, i.e. the actual flaw
area, can be determined by the flaw boundary method.
If, however, the sound beam is relatively broad, the flaw
area determined can substantially differ from the actual
flaw area. Care should therefore be taken to select a
probe which will give a sufficiently narrow sound beam
at the position of the flaw.
Echo display comparison method
The echo from a small, natural flaw is usually smaller
than the echo from an artificial comparison flaw, e.g. cir
cular disc flaw of the same size. This is due, for instance, to the roughness of the surface of a natural flaw,
or to the fact that the sound beam does not impinge on
it at right angles.
If this fact is not taken into account when evaluating natural flaws, there is a risk of false evaluation.
In the case of very jagged or fissured flaws, e.g. shrink
holes in castings, it may be that the sound scattering oc
curring at the boundary surface of the flaw is so strong
that no echo at all is produced. In such cases, a different
evaluation method should be chosen, e.g. use of the
backwall echo attenuation in the evaluation.
The distance sensitivity of the flaw echo plays an important part when testing large components. Pay close attention to choosing artificial comparison flaws which are
as far as possible governed by the same "distance laws"
as the natural flaws to be evaluated.
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USM 36Issue 2 (12/2013)1-7
1 IntroductionImportant information on ultrasonic testing
The ultrasonic wave is attenuated in any material. This
sound attenuation is very low, e.g. in parts made of finegrained steel, likewise in many small parts made of oth
er materials. However, if the sound wave travels larger
distances through the material, a high cumulative sound
attenuation can result, even with small attenuation coef
ficients. There is then a danger that echoes from natural
flaws appear too small. For this reason, an estimate
must always be made of the effects of attenuation on the
evaluation result and taken into account if applicable.
If the test object has a rough surface, part of the incident
sound energy will be scattered at its surface and is not
available for the test. The larger this initial scattering, the
smaller the flaw echoes appear, and the more errors oc
cur in the evaluation result.
It is therefore important to take the effect of the test object's surfaces on the height of the echo into account
(transfer correction).
1-8Issue 2 (12/2013)USM 36
The USM 361 Introduction
1.3The USM 36
The USM 36 is a lightweight and compact ultrasonic
flaw detector which is especially suitable for:
● for locating and evaluating material flaws,
● for measuring wall thicknesses,
● for saving and documenting test results.
USM 36Issue 2 (12/2013)1-9
1 IntroductionThe USM 36
Due to its design, the USM 36 can be used in most flaw
detection applications in a wide range of industries, in
cluding aerospace, power generation, automotive, as
well as oil and gas. These include:
Weld inspection
● Trigonometric projections
● AWS
● DAC
● DGS
Inspection of forgings and castings
● Manual PRF adjustment
● Phantom echo detector
● DGS
Rail inspection
● High PRF (up to 2000 Hz)
● Lightweight: 2.2 kg
● Small and ergonomic
Inspection of composites
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● RF display
● 3 gates A, B, and C
● Gate B is triggered by the event in gate A
For even more demanding applications
● Narrow band-pass filters
● Low-noise digital amplifiers
● Optional square pulsers
● DAC (TCG)
● Backwall echo attenuation (BEA)
1-10Issue 2 (12/2013)USM 36
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