Page 321 - CITS - Welder - Trade Practical

WELDER - CITS

EXERCISE 91 : Evaluate welding defects using cleaners

and perform Magnetic Particle Testing

Objectives

At the end of this exercise, you will be able to:
• Magnetize the object. Run a magnetic current through the material
• If defects are present, they will create a secondary magnetic field, or flux leakage field. Spread metal
particles on the object
• Spread metal particles over the material or object in the form of a powder or liquid.

Job Sequence

- Magnetic particle inspection is an inspection method used to identify defects on the surface of ferromagnetic
materials by running a magnetic current through it.
- It can also be used to detect defects just beneath the surface of materials.
- The types of defects it can detect include cracks, pores, cold lap, and the lack of sidewall fusion in welds.
- Magnetic particle inspection (MPI) is also commonly called magnetic particle testing (MT), magnetic testing, or
particle inspection.
- In this guide, we will use the terms magnetic particle inspection and magnetic particle testing and other
permutations like magnetic particle inspection test interchangeably, following the alternate terms listed above.
- Magnetic particle inspections work by running a magnetic current through the material that is being inspected.
- When the current is interrupted by a defect magnetism spreads out from that point, indicating its presence and
allowing inspectors to identify its location in the material.
- Magnetic testing is one of the more commonly used non-destructive testing (NDT) methods because it is quick
and relatively inexpensive.
- However, it only works on materials that can be magnetized—called ferromagnetic materials—so its applications
are somewhat limited.
- Some examples of ferromagnetic materials include steel, cobalt, iron, and nickel.
Wear protective clothing.

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