The difference between NDT Level I, II and III is responsibility. Level I performs tests by following written instructions. Level II sets up equipment, interprets and evaluates results against codes, and writes instructions for Level I. Level III establishes techniques and procedures, interprets codes and selects the test method. This split follows SNT-TC-1A.
Duties by level
| Level I | Level II | Level III | |
|---|---|---|---|
| Main role | Performs specific calibrations, tests and evaluations | Sets up and calibrates equipment, interprets and evaluates results | Establishes techniques and procedures, interprets codes, selects methods |
| Instructions | Works to written instructions | Prepares written instructions from codes, standards and procedures | Approves procedures and instructions |
| Accept or reject | Only by written instructions (SNT-TC-1A) | Evaluates results against acceptance criteria | Helps set criteria where none exist |
| Guidance | Works under a Level II or III | Guides trainees and Level I | Trains and examines Level I and II |
| Reporting | Records results | Organises and reports results | Responsible for the facility or method |
| Exams | General, Specific, Practical | General, Specific, Practical | Basic, Method, Specific |
Level I: the performer
Level I performs tests and records the results by following written instructions, under the supervision of a Level II or III. Under SNT-TC-1A, a Level I may accept or reject parts only when following written instructions. Level I does not choose the test method.
Level II: the evaluator and instruction writer
Level II sets up and calibrates equipment, interprets and evaluates results against codes, standards and specifications, prepares written instructions, guides Level I, and reports results. A Level II must also know the scope and limits of the method. If you want to be the person who decides whether an indication is accepted or rejected, Level II is your goal.
Level III: the technical authority
Level III establishes and validates techniques and procedures, interprets codes, designates the test method and technique, and trains and examines Level I and II. Choosing one NDT method over another is a Level III job, not Level I. A Level III also needs a practical background and knowledge of the other common NDT methods. A company without its own Level III may use an outside agency for these functions.
Who issues the certificate?
Under SNT-TC-1A, the certificate is issued by the employer according to its written practice, not by ASNT. The full explanation is in the article on NDT Level II certification under SNT-TC-1A.
Start with Level II theory
All Highkey Academy courses are designed for beginners up to Level II, in six methods: MT, PT, UT, VT, ET and RT. Lesson 1 of every course is free. See all NDT courses.
Fact source: workbooks MT pp. 66–68, 75; UT pp. 9–10, 88; VT pp. 51, 58; ET pp. 57, 91; PT pp. 47, 55.
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