Question and Answer For Magnetic Particle Testing Method Levels I, II, and III

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📘 Magnetic Particle Testing (MT) Levels I, II, and III

Question & Answer Booklet
(For Personnel Qualification & Certification in Nondestructive Testing – NDT)

Table of Contents

📖 Introduction:

Magnetic Particle Testing (MT) is a widely used Nondestructive Testing (NDT) method for detecting surface and near-surface defects in ferromagnetic materials such as iron, steel, and nickel alloys. It is fast, reliable, and cost-effective for finding cracks, seams, and other discontinuities.

This booklet offers essential Q&A for MT Levels I, II, and III based on international standards.

🔹 MT Level I: Basic Questions & Answers

Q1: What is Magnetic Particle Testing (MT)?
A1: MT is an NDT method used to detect surface and near-surface defects in ferromagnetic materials by applying magnetic fields and ferrous particles.

Q2: How does MT work?
A2: A magnetic field is applied to the test object. If there is a flaw, it disturbs the field, causing magnetic flux leakage. Magnetic particles gather at the leakage site, making the defect visible.

Q3: What materials can be tested using MT?
A3: Only ferromagnetic materials like carbon steel, low alloy steel, cast iron, and some stainless steels.

Q4: What types of particles are used in MT?

Dry magnetic particles (for rough surfaces or field work)
Wet magnetic particles (suspended in oil or water for smoother surfaces)

Q5: What are the basic magnetization methods?

Longitudinal magnetization
Circular magnetization
Yoke method
Prod method

🔹 MT Level II: Intermediate Questions & Answers

Q1: What types of defects can MT detect?

Surface cracks
Subsurface cracks (shallow)
Seams
Laps
Porosity (if close to surface)

Q2: What is the difference between AC and DC magnetization?

AC (Alternating Current): Best for surface defects.
DC (Direct Current or HWDC/HWAC): Can detect subsurface defects.

Q3: What is the purpose of demagnetization?
A3: To remove any residual magnetism from the part after testing, which could affect further processing or service performance.

Q4: What is an indication vs. a discontinuity in MT?

Indication: Visible accumulation of magnetic particles.
Discontinuity: The actual physical defect that caused the indication.

Q5: What acceptance standards are used in MT?
A5: Codes such as ASME Section V, ASTM E709, AWS D1.1 provide guidelines on acceptable and rejectable indications.

🔹 MT Level III: Advanced Questions & Answers

Q1: What factors affect the sensitivity of MT?

Strength of the magnetic field
Direction of magnetization
Particle size and type
Surface cleanliness and roughness

Q2: What is the importance of magnetizing in multiple directions?
To ensure detection of defects in all orientations, as some discontinuities may not produce indications if the magnetic field is parallel to the defect.

Q3: What are some common magnetization techniques?