Basic knowledge of Non-Destructive Testing (NDT) and Destructive Testing (DT)

1.  What is Non-Destructive Testing (NDT)?

NDT is the testing of materials to detect internal and surface defects or discontinuities using methods which do not damage or destroy the material under test

2.    What is the different between Defects or discontinuities?

Discontinuities: Any imperfection or interruption in the normal physical structure or configuration of a product (cracks, laps, inclusion, etc). Discontinuity may or may not affect the usefulness of the product

Defect:  A discontinuity whose size, shape, orientation, location or properties makes it detrimental to the useful service of the product in which it occurs or exceeds the accept/reject criteria for the given design. Defect is a type of discontinuity.

3.    What are the major 5 NDT methods?

The major 5 NDT Methods are:

a.    Ultrasonic Testing

b.    Radiography Testing

c. Magnetic Particle Testing

d.   Dye Penetrant Testing

e. Eddy Current Testing

4.    For detection of surface weld defects or discontinuities what are the NDT methods commonly used?

The NDT methods are commonly used to detect the defect/discontinuities on surface weld:

a.    Visual Testing (VT)

b.    Penetrant Testing (PT)

c.    Magnetic Particle Testing (MT)

d.   Eddy Current Testing (ET)

5.    For detection of internal weld defects or discontinuities, material what are the NDT methods commonly used?

The NDT methods to detect internal weld defect/discontinuities:

a.    Radiographic Testing (RT)

b.    Ultrasonic Testing (UT)

6.    What are the factors affecting the choice of NDT method

Depends on many factors and conditions

a.    Cost

b.    Type of defect sought

c.    Type of material to be tested

d.   Position and location of defect

e.    Availability of equipment

f.     Availability of qualified operators

g.    Working conditions and location

h.    Sensitivity required

i.      others

           

7.    What is Destructive Testing (DT)?

Destructive Testing is the testing of materials to detect internal and surface defects or discontinuities by methods which damaging or destroying the material under test

           

8.    What are the DT (Destructive Testing) methods widely applied?

           

The DT methods widely used are as follows:

a.    Tensile Test

b.    Bend Test

c.    Charpy Test

d.   Vicker Test

e.    Fracture Test

f.     Fatigue Test

g.    Creep Test

h.    Replica