There are multiple NDT certification systems worldwide, but they can generally be divided into two main types: “employer-based” and “central” certification systems.
Employer-based certification systems are systems in which the employers are responsible for the administration of the training and the qualification examinations of their own employees, as well as the documentation of the required training, examinations and experience in accordance with an employer-based standard or recommended practice.
Upon proof of qualification, the employer may issue a certificate, which can be a formal certificate or in letter format and can authorize their personnel to perform NDT tasks. In all employer-based systems, the employer is responsible for authorizing their personnel to perform such work. Because employer-based certification is usually tailored to an employer’s specific needs, the resulting certifications expire when an employee leaves the company that issued the certification.
Central certification systems are systems in which the qualification examinations are administered by an independent third-party certification body based on a central certification standard. To be eligible to sit for these examinations, prospective candidates must provide acceptable documentation of their training and experience to the certification body. Upon successful completion of the third-party examinations, the certification body will issue a certificate attesting to the fact that the named certificate holder has met the requirements and passed the examinations described in the third-party certification system. The employer can then choose to accept the third-party certificate(s) as proof of qualification. As with employer-based systems, the employer has the ultimate responsibility to certify (authorize) the certificate holder to perform NDT tasks.
SNT TC-1A, Personnel Qualification and Certification in Nondestructive Testing, 2015 Edition, is a recommended practice developed by the American Society for Nondestructive Testing (ASNT) and updated annually, that provides guidelines for employers establishing an in-house certification program for nondestructive examination. SNT TC-1A has been widely used by employers as a framework for in-house NDT certification programs since 1966 and is reviewed every five years.
This recommended practice helps ensure a minimum level of competency for NDT practitioners and applies to NDT methods such as: eddy current testing, liquid penetrant testing, magnetic particle testing, radiography, ultrasonic testing, and visual testing. Many owner-operators in the United States require ASNT certifications for personnel performing NDT.
SNT TC-1A establishes three different levels of qualification, each with more duties and responsibilities than the last. Moving from one level to another is based on a combination of education, experience, training, and passing qualification examinations. Personnel at each of the three levels tend to require recertification every five years.
- Level I: Of the three levels, those at Level I have the fewest responsibilities. Level I Practitioners are only qualified to perform specific calibration, examinations, and evaluations with specific written instructions.
- Level II: At Level II, practitioners gain more duties and responsibilities, and are qualified to set up and calibrate equipment and to interpret and evaluate the results of inspections. Level II technicians are also required to be able to prepare written instructions, provide on the job training, and report inspection results.
- Level III: Finally, at Level III, practitioners must be capable of establishing techniques, interpreting codes, and designing test methods and techniques to be used. Those at Level III are also able to train and examine Level I and II technicians for certification.
Core Certification Requirements: Training, Examination, Experience:
- Training. NDT training is based on Topical (Training Course) Outlines. The collection of these outlines form a document called the NDT Body of Knowledge (BOK). The ASNT NDT Body of Knowledge can be found in the ANSI/ASNT American National Standard CP-105, ASNT Standard Topical Outlines for Qualification of Nondestructive Testing Personnel. Minimum number of training hours are specified into the standard per each NDT Methods.
- The examinations for advancement are made up of four parts. These include an eye exam for vision acuity and color contrast discrimination, a written portion to gauge general knowledge of basic principles of methodology, a second written portion to gauge knowledge of specific equipment and techniques that will be used on the job, and finally, a practical examination based on the specific equipment that will be examined on the job. Each section requires at least a 70 to pass, while the total score of 80 for all four sections is usually required.
- Experience. Experience is defined in SNT-TC-1A as, “work activities accomplished in a specific NDT method under the direction of qualified supervision including the performance of the NDT method and related activities but not including time spent in organized training programs.” Other certification documents have similar definitions. The amount of experience-time required for each test method and/or technique is specified into the standard.
In addition to training, examinations and experience, there are multiple other requirements for the development and administration of an in-house certification program, including development of a Written Practice (or procedure), recertification requirements and certification documentation.
Written Practice. Because Recommended Practice No. SNT-TC-1A provides guidelines; employers are required to create a company NDT certification procedure known as a “Written Practice.” Employers must review the SNT-TC-1A guidelines and determine which guidelines apply to their NDT requirements, then they must create a procedure for the control and administration of NDT personnel training, examination and certification. The Written Practice should describe the responsibility of each level of certification for determining the acceptability of materials or components in accordance with applicable codes, standards, specifications and procedures, and must describe the training, experience and examination requirements for each level of certification. When included in the Written Practice, the selected guidelines become the certification requirements for the company.