1. Non-Destructive Testing
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INTRODUCTION TO NON-DESTRUCTIVE TESTING
Testing
It is defined as to take measures to check the quality, performance or reliability of a material,
especially before putting it into wide-spread use or practice
There are two types of testing:
1. Destructive Testing
It is a method of inspecting or measuring materials with doing harm
Eg: Impact Testing, Hardness Testing
2. Non-Destructive Testing
It is a method of inspecting or measuring materials without doing any harm
Eg: Magnetic Particle Testing, Radiographic Testing
Non-Destructive Testing methods:
i. Visual Testing
ii. Radiographic Testing
iii. Magnetic Particle Testing
iv. Liquid or Dye Penetrant Testing
v. Eddy Current Testing
vi. Ultra-sonic Testing
vii. Acoustic Emission Testing
viii. Infrared or Thermal Testing
ix. Leak Testing
x. Vibration Analysis
xi. Neutron Radiography Testing
Visual Testing
This is the most common and basic inspection method. This includes:
 Fibrescopes, Boroscopes, magnifying glasses and mirrors
 Portable video inspection with zoomed lenses for large tanks and vessels, server lines
 Robotics crawlers to observe hazardous or tight areas such as air ducts, reactors and
pipe lines
Instruments used for Visual Testing
1. Steel Ruler
2. Indirect Calipers
3. Vernier Calipers
4. Dial Calipers
5. Digital Calipers
6. Direct Reading Calipers

2. Non-Destructive Testing
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7. Mechanical Gauges
8. Fillet Weld Gauges
Non-Destructive Evaluation
It is a method of evaluating materials using different non-destructive techniques
Applications of Non-Destructive Evaluation
 To assist in product development
 Screening or sorting the incoming materials
 To monitor, improve or control manufacturing process
 To verify proper processing such as heat treatment
 To verify proper assembly
 To inspect for in-service damage
Homogeneous materials
Materials without cracks are called Homogeneous materials
Non- Homogeneous materials
Materials with cracks are called Non- Homogeneous materials
Defects and Discontinuities
1. Defect
Defect is a material failure
Types of Defects:
 Sensitivity
It is the smallest possible defect in a material
 Resolution
It is represented by two or more straight line or cross line defects
2. Discontinuity
It is a local variation in the material due to transportation or atmospheric conditions
Types of Discontinuities
 Surface Discontinuity
These are open to the surface of the material
Testings’ used are:
i. Visual Testing
ii. Magnetic Particle Testing
iii. Liquid or Dye Penetrant Testing

3. Non-Destructive Testing
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 Sub-Surface Discontinuity
These are present beneath the surface of the material
Testings’ used are:
i. Ultra-sonic Testing
ii. Radiographic Testing
iii. Magnetic Particle Testing (up to 6mm)
Applications of Non-Destructive Testing
a. Power plant Inspection
b. Wire Rope Inspection
c. Storage Tank Inspection
d. Air craft Inspection
e. Pipe-line Inspection
f. Rail Inspection
g. Bridge Inspection