What it is, how it works, personnel levels, training and experience requirements, examinations, and the questions nobody answers clearly.
BY DAN YAMASHITA · ASNT/PCN LEVEL 3 · SIMPLE NDT ·
SNT-TC-1A (Recommended Practice No. SNT-TC-1A) is a document published by the American Society for Nondestructive Testing (ASNT) that serves as a guideline for companies to develop their own internal programs for the qualification and certification of Nondestructive Testing (NDT) personnel.
A crucial point: SNT-TC-1A is not a standard. It is a recommended practice. This means each company has the flexibility to adapt the guidelines to its own reality, as long as those adaptations are documented in its Written Practice.
Certification performed in accordance with SNT-TC-1A is often referred to as "ASNT certification" — incorrectly. Only certificates issued directly by ASNT (such as ASNT NDT Level III or ACCP) can properly be called ASNT certification. SNT-TC-1A certification is issued by the employer, not by ASNT.
SNT-TC-1A is recognized by codes such as ASME, API, AWS, ASTM, and AMPP.
Full responsibility for certification rests with the employer. Even when external agencies (independent Level 3 consultants) are engaged for training or examination, the employer remains responsible for ensuring that these services comply with its Written Practice — and for the final certification.
In practice, many companies adopt an inadequate interpretation of this principle: they delegate full responsibility to the external Level 3 and exempt themselves from process oversight. This compromises inspector technical competence and can lead to serious problems during audits.
Each company creates its own Written Practice describing the requirements for qualification and certification. Employers may adapt SNT-TC-1A guidelines — for example, by creating limited certifications (sub-levels) for specific scopes.
Although limiting scope is not common practice (e.g., certification valid only for butt welds), it is the employer's responsibility to understand the complexity of the inspections, know the limitations of their inspectors, and provide adequate training for each type of application.
Performs all test steps except evaluation of results. Must receive instruction and supervision from a certified Level II or III. May segregate parts and record indications. The employer's Written Practice may allow Level I to perform and sign final acceptance, provided it is in accordance with written procedures.
Interprets procedures and standards. Performs and evaluates results in accordance with procedures. Issues test reports. May train and supervise Level I personnel and trainees.
The highest level. Responsible for establishing techniques, developing, qualifying, and approving NDT procedures. Interprets codes, standards, and specifications. Recommends the most appropriate method when not pre-established. Certifies Level I and Level II inspectors in NDT methods.
Learn more about Level 3 services: personnel qualification and procedure development.
SNT-TC-1A defines minimum hours of formal training and supervised practical experience for each method and level. Values vary by method — ultrasonic testing and radiographic testing require significantly more hours than visual testing or liquid penetrant testing.
An individual may be qualified directly to Level II without prior Level I certification, provided the training and experience requirements include the combined hours for both levels.
Need training for your team? See the available training programs.
Covers the basic principles of the applied method: physics, equipment, terminology, and technique fundamentals.
Covers equipment, operating procedures, and test techniques, as well as codes, standards, specifications, and acceptance criteria applicable to the employer.
The candidate demonstrates familiarity and ability to operate equipment and analyze results. At least one specimen containing a discontinuity must be tested.
Annual mandatory examination: near-distance visual acuity capable of reading Jaeger Number 1 at 12 inches (30.5 cm), natural or corrected. Additionally, color differentiation testing (typically Ishihara) and/or gray-scale discrimination for radiography.
The interval is 5 years for all levels. Recertification requires evidence of satisfactory performance or re-examination at the discretion of the Level III. For ASME, technical performance evaluation is mandatory prior to recertification of Level I and Level II personnel.
Examinations, Written Practice, training, or consulting. All certified methods available.