8/10/2019 NDT. 29.12.08
1/46
Introduction to
Nondestructive Testing
8/10/2019 NDT. 29.12.08
2/46
8/10/2019 NDT. 29.12.08
3/46
Methods of NDT
8/10/2019 NDT. 29.12.08
4/46
What are Some Uses
of NDE Methods?
Flaw Detection and Evaluation
Leak Detection
Location Determination
Dimensional Measurements
Structure and Microstructure Characterization
Material Sorting and Chemical Composition
Determination
Fluorescent penetrant indication
8/10/2019 NDT. 29.12.08
5/46
8/10/2019 NDT. 29.12.08
6/46
Common NDT Methods
Visual Liquid Penetrant Magnetic Ultrasonic
X-rayEddy Current
8/10/2019 NDT. 29.12.08
7/46
VISUAL TESTING
To support other NDT methods
Direct unaided and aided
Stages of Inspection
Tools
Merits Demerits
8/10/2019 NDT. 29.12.08
8/46
Most
basic and common
inspection method.
Tools include fiber
scopes, borescopes,
magnifying glasses and
mirrors.
Robotic crawlers permit
observation in hazardous or
tight areas, such as air
ducts, reactors, pipelines.
Portable video inspection
unit with zoom allows
inspection of large tanks
and vessels, railroad
tank cars, sewer lines.
Visual Inspection
8/10/2019 NDT. 29.12.08
9/46
8/10/2019 NDT. 29.12.08
10/46
Throat measurement
using a Palmgren
gage.
Leg size
determination with
fillet gage.
Convexity measurement
with VWAC gage.
Measurement of undercut depth
with VWAC gage.
8/10/2019 NDT. 29.12.08
11/46
8/10/2019 NDT. 29.12.08
12/46
Basic Process of PT
1) Clean Dry Component
4) Apply Developer
2) Apply Penetrant
3) Remove Excess
5) Visual Inspection
6) Post Clean Component
8/10/2019 NDT. 29.12.08
13/46
Basic Process of PT
8/10/2019 NDT. 29.12.08
14/46
Choices of Penetrant Materials
Penetrant Type
I Fluorescent
II Visible
Method
A Water Washable
B Postemulsifiable - Lipophilic
C Solvent Removable
D Postemulsifiable - Hydrophilic
Developer Form
Dry Powder
Wet, Water Soluble
Wet, Water Suspendable
Wet, Non-Aqueous
8/10/2019 NDT. 29.12.08
15/46
A liquid with high surface wetting characteristicsis applied to the surface of the part and allowed
time to seep into surface breaking defects.
The excess liquid is removed from the surfaceof the part.
A developer (powder) is applied to pull thetrapped penetrant out the defect and spread it
on the surface where it can be seen.
Visual inspection is the final step in the
process. The penetrant used is often loaded
with a fluorescent dye and the inspection is
done under UV light to increase test sensitivity.
Liquid Penetrant Inspection
8/10/2019 NDT. 29.12.08
16/46
Magnetic Particle Inspection
The part is magnetized. Finely milled iron particles coatedwith a dye pigment are then applied to the specimen. These
particles are attracted to magnetic flux leakage fields andwill cluster to form an indication directly over thediscontinuity. This indication can be visually detected underproper lighting conditions.
8/10/2019 NDT. 29.12.08
17/46
Magnetic Particle TestingThe flaw (for example, a crack) is located
from the "flux leakage", following theapplication of fine iron particles, to the
area under examination. There are
variations in the way the magnetic field
is applied.
N S
IRON POWDER
S NN S
IRON POWDER
CRACK
CRACK
8/10/2019 NDT. 29.12.08
18/46
8/10/2019 NDT. 29.12.08
19/46
8/10/2019 NDT. 29.12.08
20/46
Film Radiography
Top view of developed film
X-rayfilm
The part is placed between the radiationsource and a piece of film. The part will stop
some of the radiation. Thicker and more
dense area will stop more of the radiation.
= more exposure
= less exposure
The film darkness (density) willvary with the amount of radiation
reaching the film through the test
object.
8/10/2019 NDT. 29.12.08
21/46
Radiographic Images
8/10/2019 NDT. 29.12.08
22/46
8/10/2019 NDT. 29.12.08
23/46
8/10/2019 NDT. 29.12.08
24/46
High frequency sound waves are introduced into a material andthey are reflected back from surfaces or flaws.
Reflected sound energy is displayed versus time, and inspector canvisualize a cross section of the specimen showing the depth offeatures that reflect sound.
f
plate
crack
0 2 4 6 8 10
initialpulse
crack
echo
back surfaceecho
Oscilloscope, or flaw
detector screen
Ultrasonic Inspection (Pulse-Echo)
8/10/2019 NDT. 29.12.08
25/46
8/10/2019 NDT. 29.12.08
26/46
Ultrasonic Testing
8/10/2019 NDT. 29.12.08
27/46
Common Application of NDT
Inspection of Raw Products Inspection Following
Secondary Processing In-Services DamageInspection
8/10/2019 NDT. 29.12.08
28/46
Inspection of Raw Products
Forgings,
Castings, Extrusions, etc.
8/10/2019 NDT. 29.12.08
29/46
Machining Welding Grinding
Heat treating Plating etc.
Inspection Following
Secondary Processing
8/10/2019 NDT. 29.12.08
30/46
CrackingCorrosion
Erosion/WearHeat Damageetc.
Inspection For
In-Service Damage
8/10/2019 NDT. 29.12.08
31/46
Power Plant Inspection
Probe
Signalsproduced by
variousamounts ofcorrosionthinning.
Periodically, power plants are
shutdown for inspection.Inspectors feed eddy currentprobes into heat exchanger tubesto check for corrosion damage.
Pipe with damage
8/10/2019 NDT. 29.12.08
32/46
Wire Rope Inspection
Electromagnetic devices and visualinspections are used to find broken
wires and other damage to the wirerope that is used in chairlifts, cranesand other lifting devices.
8/10/2019 NDT. 29.12.08
33/46
Storage Tank Inspection
Robotic crawlers use
ultrasound to inspectthe walls of largeabove ground tanks forsigns of thinning dueto corrosion.
Cameras on longarticulating arms
are used to inspectundergroundstorage tanks fordamage.
8/10/2019 NDT. 29.12.08
34/46
Aircraft Inspection
Nondestructive testing is usedextensively during the
manufacturing of aircraft. NDT is also used to find cracks andcorrosion damage duringoperation of the aircraft.
A fatigue crack that started at the
site of a lightning strike is shownbelow.
8/10/2019 NDT. 29.12.08
35/46
Jet Engine Inspection
Aircraft engines are overhauledafter being in service for a period of
time. They are completely disassembled,cleaned, inspected and thenreassembled.
Fluorescent penetrant inspection is
used to check many of the parts forcracking.
8/10/2019 NDT. 29.12.08
36/46
8/10/2019 NDT. 29.12.08
37/46
Pressure Vessel Inspection
The failure of a pressurevessel can result in the rapid
release of a large amount ofenergy. To protect againstthis dangerous event, thetanks are inspected usingradiography and ultrasonic
testing.
8/10/2019 NDT. 29.12.08
38/46
Rail Inspection
Special cars are used to inspect
thousands of miles of rail to findcracks that could lead to aderailment.
8/10/2019 NDT. 29.12.08
39/46
Bridge Inspection
The US has 578,000highway bridges.
Corrosion, cracking andother damage can allaffect a bridgesperformance.
The collapse of the Silver
Bridge in 1967 resultedin loss of 47 lives.
Bridges get a visualinspection about every 2years.
Some bridges are fittedwith acoustic emissionsensors that listen forsounds of cracksgrowing.
8/10/2019 NDT. 29.12.08
40/46
NDT is used to inspect pipelines toprevent leaks that could damage theenvironment. Visual inspection,radiography and electromagnetictesting are some of the NDT methodsused.
Remote visual inspection usinga robotic crawler.
Radiography of weld joints.
Magnetic flux leakage inspection. Thisdevice, known as a pig, is placed in thepipeline and collects data on thecondition of the pipe as it is pushed
along by whatever is beingtransported.
Pipeline Inspection
8/10/2019 NDT. 29.12.08
41/46
Special Measurements
Boeing employees in Philadelphia were given the privilege ofevaluating the Liberty Bell for damage using NDT
techniques. Eddy current methods were used to measure theelectrical conductivity of the Bell's bronze casing at variouspoints to evaluate its uniformity.
8/10/2019 NDT. 29.12.08
42/46
For More Information on NDT
The Collaboration for NDT
Education
www.ndt-ed.org
The American Society
for Nondestructive
Testing
www.asnt.org
8/10/2019 NDT. 29.12.08
43/46
THANK YOU
S.PONNAPPAN
8/10/2019 NDT. 29.12.08
44/46
8/10/2019 NDT. 29.12.08
45/46
Eddy Current Testing
Eddy current testing is particularly well suited for detectingsurface cracks but can also be used to make electrical
conductivity and coating thickness measurements. Here a smallsurface probe is scanned over the part surface in an attempt todetect a crack.
LIMITATIONS OF DPT
8/10/2019 NDT. 29.12.08
46/46
LIMITATIONS OF DPT
- Poor repeatability of test.
- Retest should be done with same type of
penetrant only.
- Can not give the indication for depth.
- Not suitable for porous material.
- Not applicable for hidden defects.