NDT ( NON DESTRUCTIVE TESTING )

NDT (NON DESTRUCTIVE TESTING) :-

Non Destructive Testing in great variety are in world wide used to detect variations in structure,minute changes in surface finish, the presence of cracks or other physical discontinuities,measure the thickness of materials and coatings and to determine other characteristics of industrial products.

REASON'S FOR THE USE OF NDT:

"NDT" is used by the manufacturers for the following reasons:

1. To ensure product reliability.

2. To make profit for the user.

a) To ensure customer satisfaction

b) To aid in better product reliability.

c) To control the manufacturing processes.

d) To lower the manufacturing costs.

e) To maintain uniform quality level.

SOME OF THE MOST COMMON NDT METHODS ARE :

1.VISUAL INSPECTION

2.LIQUID PENETRATION TEST

3.MAGNETIC PARTICLE TEST

4.RADIOGRAPHY TEST

5.ULTRASONIC TEST

The Brinell Hardness Test

The Brinell Hardness Test The Brinell hardness test method consists of indenting the test material with a 10 mm diameter hardened steel or carbide ball subjected to a load of 3000 kg. For softer materials the load can be reduced to 1500 kg or 500 kg to avoid excessive indentation. The full load is normally applied for 10 to 15 seconds in the case of iron and steel and for at least 30 seconds in the case of other metals. The diameter of the indentation left in the test material is measured with a low powered microscope. The Brinell harness number is calculated by dividing the load applied by the surface area of the indentation. The diameter of the impression is the average of two readings at right angles and the use of a Brinell hardness number table can simplify the determination of the Brinell hardness. A well structured Brinell hardness number reveals the test conditions, and looks like this, "75 HB 10/500/30" which means that a Brinell Hardness of 75 was obtained us...

VISUAL INSPECTION OF WELDING

VISUAL INSPECTION OF WELDING INTRODUCTION Inspection starts with examination of the material prior to fabrication, scabs, seams, scale or other harmful surface conditions may be detected in visual inspection. The inspector should check the following : Weld preparation, dimensions and finish. Clearance dimensions of backing strips. Alignment and fit up to the pieces being welded. Verification of cleanliness. Visual Inspection During Welding Visual inspection checks details of the work while welding is in progress. Among the details to be checked are : Welding process. Cleaning. Preheat and inter pass temperature. Joint preparation. Filler metal. Flux or shielding gas. Chipping, grinding, or gouging. Post heating temperature and time. Visual Inspection After Welding Visual inspection is useful for finished-product verification of such items as : Profile irregularities of the weldment....

'NICK' BREAK (BEND) TEST

'NICK' BREAK (BEND) TEST Object : As for fillet weld fracture, used on butt welds. Method: The specimen is cut transversely to the weld, and a saw cut is applied along the center of the weld face. The best place for the cut is at a start I stop. The specimen is fractured by bending or by hammer blows. The nick bend test will find internal defects. Reporting Results: Thickness of material. Width of specimen. Location of fracture. Appearance of joint after fracture.

Mechanical Engineering

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