Ultrasonic testing

106 Pages·2012·6.8 MB·English

ATSNY© 2012 1

Basic Nondestructive
Testing

for EXPO 2012
by
Neville W. Sachs, P.E.
Applied Technical Services New York

ATSNY© 2012 2

What we plan to cover

1. Definition of nondestructive testing
2. Some philosophy on why it is helpful
and the major pitfalls

3. Basic theory
4. Explanations of common techniques
5. Demonstrations of common analysis
techniques

ATSNY© 2012 3

Nondestructive Testing
(NDT)

 Also known as nondestructive examination
(NDE)

 Involves inspection and analysis of
machinery or components without affecting
the operation or the properties of the subject.
(As opposed to a tensile test or other
destructive test such as sectioning.)

ATSNY© 2012 4

From the ASNT Website
(American Society for Nondestructive Testing)

What Is Nondestructive Testing?
 Nondestructive testing asks “Is there
something wrong with this material?”

 Nondestructive testing (NDT) has been
defined as … “those test methods used to
examine an object, material or system without
impairing its future usefulness.”

ATSNY© 2012 5

The British View (BINDT)

 “Non-destructive testing is the branch of engineering
concerned with all methods of detecting and
evaluating flaws in materials.”

 “The essential feature of NDT is that the test process
itself produces no deleterious effects on the material
or structure under test.”

 “The subject of NDT has no clearly defined
boundaries …”

ATSNY© 2012 6

A Brief History

Formal NDE dates back to early railroad days
when a mixture of oil and talc were used to detect
cracking in axles and wheels.

Since then science has developed a wide range of
tools and abilities to noninvasively detect
problems before they become disasters.

ATSNY© 2012 7

Wikipedia says
nondestructive testing is …


Acoustic emission testing (AE or AT)


Blue Etch Anodize (BEA)


Dye penetrant inspection Liquid penetrant testing (PT or LPI)


Electromagnetic testing (ET)

•
Alternating current field measurement (ACFM)

•
Alternating current potential drop measurement (ACPD)

•
Barkhausen testing

•
Direct current potential drop measurement (DCPD)

•
Eddy-current testing (ECT)

•
Magnetic flux leakage testing (MFL) for pipelines, tank floors, and wire rope

•
Magnetic-particle inspection (MT or MPI)

•
Remote field testing (RFT)


Ellipsometry


Guided wave testing (GWT)


Hardness testing


Impulse excitation technique (IET)


Infrared and thermal testing (IR)

•
Thermographic inspection


Laser testing

•
Electronic speckle pattern interferometry

•
Holographic interferometry

•
Low coherence interferometry

•
Profilometry

•
Shearography


Leak testing (LT) or Leak detection

•
Absolute pressure leak testing (pressure change)

•
Bubble testing

•
Halogen diode leak testing

•
Hydrogen leak testing

•
Mass spectrometer leak testing

•
Tracer-gas leak testing method Helium, Hydrogen and refrigerant gases

Magnetic resonance imaging (MRI) and NMR
spectroscopy
Metallographic replicas [7] [8]
Near-infrared spectroscopy (NIRS)
Optical microscopy
Positive Material Identification (PMI)
Radiographic testing (RT) (see also Industrial
radiography and Radiography)

Computed radiography
Digital radiography (real-time)
Neutron radiographic testing (NR)
SCAR (Small Controlled Area Radiography)
X-ray computed tomography (CT)

Scanning electron microscopy
Surface Temper Etch (Nital Etch)
Ultrasonic testing (UT)

ART (Acoustic Resonance Technology)
Electro Magnetic Acoustic Transducer (EMAT)
(non-contact)
Laser ultrasonics (LUT)
Internal rotary inspection system (IRIS)
ultrasonics for tubes
Phased array ultrasonics
Time of flight diffraction ultrasonics (TOFD)
Time of Flight Ultrasonic Determination of 3D
Elastic Constants (TOF)
Vibration Analysis
Visual inspection (VT)

Pipeline video inspection
Corroscan/C-scan
IRIS - Internal Rotary Inspection System
3D Computed Tomography

Industrial CT Scanning
Heat Exchanger Life Assessment System
RTJ Flange Special Ultrasonic Testing

ATSNY© 2012 8

So, going back to the ASNT website,
these are the common NDT
techniques

Acoustic Emission
Eddy Current
Liquid Penetrant Magnetic Particle
Ultrasonic Testing Visual Inspection
Vibration Analysis
Radiography (X-ray)

Also common are:
Infrared Thermography Hardness Testing

ATSNY© 2012 9

Your Personal NDT

 When you go to the market to select fruit
or veggies, what do you do? How do you
make your choice?

 If your car is making a new strange noise,
what do you do?


Do you ever glance at your car tires to
see if they are soft?

ATSNY© 2012 10

The goal –
A. Look at it without causing a
damaging interruption
B. Use the test information to
form a plan

ATSNY© 2012 11

NDT in everyday life

Would you rather have an MRI - or should
we do exploratory surgery for that knee
problem?

Would you prefer an EKG or exploratory
surgery?

For both of these, consider the possible
costs and the possible benefits.

ATSNY© 2012 12

The goal of NDT is to analyze a piece of
material, without damaging its performance
capabilities, and then use that information to
predict future performance.

The graph below shows leaks in the roof of a process
vessel. (Replacing the vessel will cost about $50,000,000
and take about a year.)
300

200

100

0
4

Routine inspections of a vessel
with stress corrosion cracking

Roof leaks
vs.
Inspection date

Years from vessel installation

Number of leaks

8
12
16
20

ATSNY© 2012 13

The goal –
Look at it without causing a
damaging interruption

So, not only can we look at and inside
pieces, but we want to do that without
causing an interruption.
Then a question arises - Do humans
really commit that many errors?

ATSNY© 2012 14

Human Error Experts say the average
person makes six significant errors per
week.

BUT, our surveys show the typical industry
person believes they make a significant
error about once every FIVE months

ATSNY© 2012 15

In 23 years of doing industrial training
programs and asking people to compare their
skills with others in the same job,
only 37 people have rated themselves as below
average!

For the last six years we have also asked people
to rate their safety awareness. Only TWO have
said they were below average!!!

( 23 years x 15 seminars/year x 15 people/seminar = 5100 students
37/5100 = 0.7% )