Discuss advantages, limitations and applications of NDT method

Advantages

• Provides permanent record on film
• Technique standardized
• Reference standards available
• Adjustable energy level gives high sensitivity
• Fluoroscopy techniques available

Limitations

• Trained technician needed
• Radiation hazards
• High cost of equipment
• Power source needed

Gamma-ray Radiography

Advantages

• Provides permanent record on film
• Technique standardized
• Reference standards available
• Low initial cost
• Portable, independent of power supply
• Makes panoramic exposures

Limitations

• Trained technician needed
• Radiation hazards
• Fixed energy levels per source
• Source looses strength continuously
• Generally lower sensitivity and definition than x-ray radiography

Ultrasonic Testing

Applications

• All types of welded work in metallic and non metallic materials

Advantages

• Safe to use
• Fast method
• Results available immediately
• Sensitive
• Indicates presence of laminations and other plannar defects
• Indicates depth of flaw

Limitations

• Entirely dependent on operator skill
• Unsuitable for welding of complex shape or configuration
• Requires surface contact
• Surface must be clean and smooth

Magnetic Particle Testing

Applications

• Welds, particularly fillet welds, in all ferro magnetic materials

Types of Faults Indicated

• Cracks, Porosity, Inclusions and discontinuities at or close to the surface

Advantages

• Simple to use and interpret
• Portable and relatively inexpensive

Limitations

• Material must be ferro magnetic
• Demagnetization may be needed
• Power source required