Recommended Practice
SNT-TC-1A (2006 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 2006 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 may be in recorded in months or hours.
This option should be determined by the employer and described
in the employer’s written practice.
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.
