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As nondestructive test (NDT) inspectors often make critical judgments that may have significant safety or commercial consequences, the need for the certification of NDT inspectors is essential for manufacturing companies. Certification ensures manufacturing companies and their customers that the NDT inspector is competent and professional.
What is NDT Certification?NDT certification is a process of providing written testimony that an individual is qualified to conduct NDT tests. Certification is confirmation that the qualification requirements have been fulfilled and this will lead to the issuing of a certificate.
In general, certification will be based on the inspector meeting the following requirements:
It should be noted that the certificate of examination is only part of the qualification process. This certificate alone is not a certificate of examination that qualifies the individual to work in NDT. The whole process of qualification, including work experience, must be considered by the employer and it is the employer’s responsibility to authorize the individual to work.
Employer-based CertificationThis is a system whereby the manufacturing company is responsible for producing, approving and maintaining its own document called a written practice. A written practice details the responsibilities for each level of certification available, as well as the required training, experience and examination requirements for each level of certification, or Level I, II or III. The advantage of the company-based certification scheme is that the training and examinations are specific not only to the method of NDT used by the manufacturer, but also the processes, procedures and products relevant to the employer’s operations.
There are documents available that provide recommendations or requirements for employers establishing a written practice. The American Society for Nondestructive Testing (ASNT) publishes such guidelines in a document called SNT-TC-1A. The most current version of this document from 2006 provides the guidelines for a manufacturer to establish a written practice and the details that may be contained in it.
Under the SNT-TC-1A certification scheme, certificates of examination are invalid once the inspector leaves the company, since he would no longer be working under that company’s written practice. This means that if the inspector joins another company, he must be re-qualified under the new company’s written practice.
This scheme, when implemented as per the guidelines, offers employers a cost-effective method of certifying NDT operators, since the training and examination is focused on the company’s written practice or procedures. This certification is often referred to as “in-house certification,” since the Level III inspector that does the certifying is, in most cases, employed by the same company as the inspector being certified.
Unfortunately, this route to certification is open to abuse and the levels of competence are not always consistent. The result of this abuse has forced some manufacturing companies not to accept company-based certificates such as SNT-TC-1A as the levels of competence may not always be trusted.
In addition, this method of certification often is misunderstood. For example, an individual working for one manufacturer may still be operating with the certificate issued by the previous manufacturer because the company believes that the certification is valid until the date has expired-however, the certificate is non-transferable in such a scenario. The result is that many signed reports by these inspectors for NDT services may not be valid and the company runs a high risk of being exposed during an audit.
Personal Central CertificationWith central certification, an operator can obtain certification from a central certification scheme that is recognized and accepted by the industry. Central certification schemes are administered and controlled by independent certification bodies. This means that the curriculum development, approval of course notes and exams, marking of examinations, issuing of certificates, appeals, and the monitoring of authorized qualifying bodies (AQBs) are the responsibility of a single certification body.
One central certification scheme, named Personnel Certification of NDT (PCN), was developed in the United Kingdom by the British Institute of NDT (BINDT). This route to certification was implemented first in the aerospace industry in 1985 and was extended into general engineering in 1998. The PCN certification scheme is recognized around the world and meets the requirements of many international standards, including EN 473, EN 45013 and ISO 9712.
Central certification schemes require minimum work experience and training criteria that must be met in order for the inspector to be eligible for certification. PCN Level III and ASNT Level III are both central certification schemes and the examinations are conducted independently. An employer-based SNT-TC-1A Level III certification often is mistaken with the ASNT Level III central certification.
Choosing a Route to CertificationNDT personnel often ask which certification route to choose when entering the field for the first time. There are different types of certification available and many different certification schemes. If the individual is seeking certification for his own career development, then a personal central certification scheme should be the obvious choice, since the investment involved allows the inspector to take that certification with him and is not restricted to working for a single company.
However, from an employer’s point of view, both the central certification and the company-based certification schemes have advantages and disadvantages. It should be noted that company-based certification (SNT-TC-1A) that was not issued by an independent organization-for example, issued by a Level III who was not independent to the employer-may not be accepted by some clients. To address this issue, many NDT personnel prefer to achieve certification through either central certification schemes or company-based schemes (SNT-TC-1A) that are conducted by independent organizations rather than by in-house Level III employees.
If central certification is the desired choice, then the operator should contact an AQB. The organization will advise the operator on the requirements and also guide them through the application process step by step. If the inspector already holds the required work experience, then he should attend a pre-examination approved training course provided by an approved training organization (ATO). It is possible that the training and examinations are provided by the same AQB.
Essentially, whichever certification method, level and sector is selected, the inspector must complete an approved training course, followed by a qualification examination.
ExaminationsRegardless of which certification route is chosen, the examination structure usually includes:
Each certification scheme should conduct a practical examination for the inspector to demonstrate competence. This is normally done by the inspector testing and reporting the findings on report forms. The samples should have known defects recorded on a master report, which will have been approved by the examiner for use. The candidate is expected to be able to reproduce the master report showing the size, location and characterization of the defects. The number of samples will vary from scheme to scheme, method to method and level to level. For example, in the PCN scheme, a Level II magnetic particle welds examination consists of three samples.
The marking of the general theory and specific theory exams is a relatively straightforward procedure; these parts of the exams are usually in the form of multiple choice questions. Because of the multiple choice format, the examiner typically only needs to cross check the answers provided by the candidate to the master marking sheet. The number of correct answers is reflected as a percentage against the total number of questions asked.
The marking of the practical examination is much more complex. The marking of employer-based examinations is governed by the contents of the company’s approved written practice. In general, this would be done by the examiner using a checklist to evaluate the performance and competence of the candidate and his ability to follow procedures. The minimum requirement for passing this examination is that all the reportable defects should be recorded by the candidate.
As with the general and specific theory parts of the examination, the marks awarded are usually reflected as a percentage of accuracy for the reporting on each sample. These marks will contribute to the grading of the overall examination.
GradingGrading of employer-based examinations should be defined in the written practice. It is quite common in the SNT-TC-1A scheme for a minimum pass mark to be 70% in each part of the examination with an overall pass mark (average) of 80%. For example, a candidate achieving 70% in general theory, 70% in specific theory and 90% practical would achieve an overall mark of 77% and may not be eligible for certification. This is merely an example, however, and the employer’s written practice would define the actual grading procedure.
A candidate who fails to achieve the required pass mark may require a re-test of a failed part or the entire examination. In the employer-based certification scheme, the employer would define the requirements for such events. Standard practice is that additional training in the failed part should be provided prior to attempting the re-test.
As an NDT inspector, it is important to be well-versed on the routes to, and the requirements for, certification in the manufacturer’s method or methods of NDT inspection-not only to perform inspections to the best of one’s ability, but to further one’s career as well. Choosing the route to NDT certification is an individual choice and involves many factors, including length of work experience, employer requirements and professional goals. NDT