Qualification

NDT Testing Personnel Qualification and Certification Standards:

ASNT Recommended Practice No. SNT-TC-1A

National Aerospace Standard NAS-410

ASNT Standard CP-189

ASNT ACCP

ASNT NDT Level III

Military Standard MIL-STD-410E

Air Transport Association Standard ATA - 105

International Standard ISO 9712

Canadian CGSB-48.9712

Recommended Practice
SNT-TC-1A (2011 Edition)

The American Society for Nondestructive Testing (ASNT) Recommended Practice No. SNT-TC-1A had its beginning in the early 1960's. The Society for Nondestructive Testing (SNT at that time) Board of Directors charged the Technical Council to develop a set of guidelines which could be used by employers to develop their own "In -house" employer based training, qualification and certification programs.

This set of guidelines, first published in 1966, is called the Recommended Practice No. SNT-TC-1A. This document established levels of qualification based upon a combination of education, training, experience, and qualification examinations. The basic levels begin with NDT Level I primarily used as an operator technician. NDT Level II, the next level requires more training and experience, but permits more independent activity including accepting and rejecting products, materials and/or components. The NDT Level III usually requires four (4) years of experience as an NDT Level II in the method. However, the number of years of experience depends upon the candidate's formal education.

While there are several personnel qualification and certification programs used, SNT-TC-1A employer based certification has been widely accepted throughout the United States as the primary guide used for NDT personnel certification. This document is revised periodically, usually every five (5) years. The current revision is the 2011 Edition.

Employer's Written Practice
SNT-TC-1A requires an internal company procedure that details how employees are trained, qualified and certified to perform NDT functions for the company.

The Written Practice should provide descriptions of:

  • Applicable NDT methods used such as Eddy Current (ET), Liquid Penetrant (PT), Magnetic Particle (MT), Radiography (RT), Ultrasonic (UT) and Visual Testing (VT).
  • Levels of personnel qualification.
    LEVEL I - qualified to perform specific calibrations, specific examinations and specific evaluations (with specific written instructions).
    LEVEL II - qualified to set-up and calibrate equipment and to interpret and evaluate results with respect to codes, standards, and specifications. Must be able to prepare written instructions, qualified to provide on-the-job training and guidance of trainees and report examination results.
    LEVEL III - must be capable and responsible for establishing techniques, interpreting codes, and designating the test method and technique to be used, and capable of training and examining NDT Level I and II personnel for certification. Must have a practical background in the technology and be familiar with other commonly used methods of NDT.
  • Certification / re-certification requirements and interruption intervals. Typically, all three (3) levels are recertified at five (5) year intervals; however, interruption intervals of inactivity for suspension of certification should be addressed.
Organized Training
The structured training program(s) meeting the recommendations of the table below from the guidelines of SNT-TC-1A should be successfully completed and documented. Common examples are:
Test Method
Level I Hours
Level II Hours
Eddy Current (ET)
40
40
Liquid Penetrant (PT)
4
8
Magnetic Particle (MT)
12
8
Radiography (RT)
40
40
Ultrasonics (UT)
40
40
Visual (VT)
8
16

Note: Level II training qualification should combine total hours for Level I and Level II.

Experience

Personnel should achieve the minimum experience level recommended which will vary for each particular NDT method. This initial experience is recorded in method hours and total NDT hours. Common examples are:

Experience by hours
Test Method
Level I Hours
Level II Hours
Total NDT Hours
Eddy Current (ET)
210
630
1600
Liquid Penetrant (PT)
70
140
400
Magnetic Particle (MT)
70
210
530
Radiography (RT)
210
630
1600
Ultrasonics (UT)
210
630
1600
Visual (VT)
70
140
400

Note: Level II experience qualification should combine total hours for Level I and Level II.

Qualification Examination

NDT Level I/II examinations include:

  • An eye exam for near vision acuity and color contrast discrimination.
  • A written "General" examination to demonstrate the candidates knowledge of the basic principles and fundamentals of the method. The minimum recommended number of questions for the general examination are given in Table 1.
  • A written "Specific" examination should be based on the equipment and the techniques that will be used on the job. The minimum recommended number of questions for the specific examination are given in Table 2.
  • A "Practical" examination should be based on the equipment, techniques and products or materials that will be examined on the job. Typically, this is a performance demonstration using at least one (1) flawed specimen. A minimum of ten (10) different checkpoints should be used to evaluate the understanding of NDT variables and the employer's procedural requirements.
Table 1 - General Examinations
Test Method
Level I Questions
Level II Questions
Eddy Current (ET)
40
40
Liquid Penetrant (PT)
40
40
Magnetic Particle (MT)
40
40
Radiography (RT)
40
40
Ultrasonics (UT)
40
40
Visual (VT)
40
40

Table 2 - Specific Examinations
Test Method
Level I Questions
Level II Questions
Eddy Current (ET)
20
20
Liquid Penetrant (PT)
20
20
Magnetic Particle (MT)
20
20
Radiography (RT)
20
20
Ultrasonics (UT)
20
20
Visual (UT)
20
20

Certification
Certification is a written statement of qualification. Using employer-based programs such as SNT-TC-1A requires employer certification. Typically, at least 70% must be achieved on each portion of the qualification examinations and an average (composite) score of at least 80% must be attained.

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