Inspection supervision in non-destructive testing: Responsibility for quality and safety

Anyone who has worked with materials testing or weld qualification will recognise the challenge: a component must be safe, the test must be reliable – and, at the end, a single signature confirms it all. This is where inspection supervision comes in. It links technical execution with regulatory assurance in non-destructive testing (NDT).

Why NDT is more important than ever

Non-destructive inspection methods(opens in new tab) allow materials, components and welded joints to be examined for defects without impairing their fitness for use. They are therefore a central part of quality assurance in many industries. Demand for these methods is growing steadily, for good reasons:

• Regulation and standardisation are increasing. More and more industries are subject to strict requirements that make the use of certified NDT methods mandatory.
• Components and equipment are expected to last longer. An extended service life requires regular, reliable condition assessments, often over several decades.
• Reputational risks need to be avoided. A product failure or recall can be costly – not only financially, but also in terms of trust in a brand.

What is inspection supervision?

Standards and regulations such as DIN EN ISO 9712 and ISO/IEC 17025 define who may perform tests, which methods must be used and the conditions under which testing must take place. Inspection supervision has a special role: it ensures that tests are properly prepared, performed and documented.

In addition to the examiners themselves, inspection supervisors are part of the testing personnel. Depending on the regulatory framework, they may be described as “supervisors”, “persons responsible for testing” or “supervisory personnel”, but their function remains the same: they oversee, direct and take responsibility for the proper execution of testing.

The main tasks of inspection supervision

Inspection supervision provides an important interface between the examiners carrying out the work, the testing laboratory or customers and manufacturers, and the applicable technical regulations. Its tasks include:

• directing materials and component testing carried out by qualified testing personnel,
• managing activities during test preparation,
• providing technical support and supervision during testing,
• ensuring compliance with relevant standards, inspection methods and requirements,
• reviewing and signing test reports.

Who is authorised to test? Qualification of testing personnel

In practice, the question of who is authorised to carry out NDT and evaluate the results arises frequently. DIN EN ISO 9712 provides the answer: certification requires personal prerequisites (e.g. visual acuity), a passed examination and documented training hours. Engineers, technicians and master craftspeople may benefit from shorter courses because their prior education can be recognised. Existing certificates may also be recognised by the relevant certification body.

It is important to know that certification is always method-specific. Certification in ultrasonic testing (UT)(opens in new tab) does not therefore authorise a person to carry out magnetic particle testing (MT)(opens in new tab) or eddy current testing (ET)(opens in new tab). Each method requires a separate qualification.

Further reading: May a certified Level 2 NDT examiner write a testing instruction and then carry out testing at an external company in accordance with it? We answer this question in our blog post “NDT in accordance with DIN EN ISO 9712: Who may prepare and approve testing instructions?” (opens in new tab)

An overview of the three NDT qualification levels

Qualified testing personnel are in short supply, making clearly defined qualification pathways even more important. EN ISO 9712 distinguishes three successive levels:

• Level 1: Examiners may carry out tests in accordance with specified instructions and document the results.
• Level 2: In addition, examiners may interpret and evaluate results in accordance with applicable standards and regulations.
• Level 3: In addition, examiners may select appropriate methods, specify testing procedures and take technical responsibility.

As a general principle, a qualified or certified Level 2 NDT examiner may prepare testing instructions. However, overall responsibility ultimately rests with Level 3 examiners. Certification alone is not sufficient. Each examiner also requires authorisation from their employer for the specific tasks they are to perform.

The prerequisites for each level are demanding and include defined periods of training and practical experience, as well as several examinations (general, specific and practical). Certificates are generally valid for five years. They must then be renewed (with evidence of continued activity and visual acuity), with full recertification typically required after ten years.

Further reading: In our blog post “Qualification levels in NDT: Tasks and responsibilities at Levels 1–3”(opens in new tab) we explain the three qualification levels in detail.

Inspection supervision in laboratories accredited to ISO/IEC 17025

Our testing laboratory, accredited to ISO/IEC 17025, is assessed by the German accreditation body, Deutsche Akkreditierungsstelle (DAkkS). Specific requirements for inspection supervision are therefore:

• Staffing: A minimum number of inspection supervisors is required depending on the number of examiners in the respective method – one supervisor for up to 20 examiners, two for up to 50 examiners and three for 50 examiners or more.
• Organisational integration: The inspection supervisor must be part of the laboratory or firmly integrated through a contractual arrangement.
• Qualification level: Level 3 in accordance with EN ISO 9712.
• Deputising arrangements: Level 2 personnel may deputise provided they have at least three years of practical experience in the respective method.
• Availability: The inspection supervisor must be contactable while testing is in progress.

Inspection supervision builds trust in NDT

Non-destructive testing works reliably when several levels interact: DIN EN ISO 9712 defines the qualification of testing personnel, while ISO/IEC 17025 establishes a framework for the technical competence of the testing laboratory. Product standards or acceptance specifications define what is tested, how it is tested and which evaluation criteria apply.

Inspection supervision brings these requirements together in practice. It ensures that qualified examiners work with appropriate methods, that results are documented traceably and that testing processes comply with the applicable requirements.

Whether at the manufacturer’s own premises or in an accredited testing laboratory, inspection supervision ensures that technical competence and regulatory assurance go hand in hand. This makes it one of the most important functions in modern materials testing, even if it often operates behind the scenes.

How we support customers with NDT

Since our founding in 2007, we have supported manufacturers, maintenance providers and operators with materials engineering issues, damage analyses and quality assurance tasks. We carry out NDT on different materials and safety-relevant components and have many years of experience with a wide range of inspection methods, particularly in the railway sector.

We also provide technical inspection supervision and support the planning, execution and evaluation of tests. Our Level 2 and Level 3 examiners, certified in accordance with DIN EN ISO 9712, combine the required qualifications with extensive practical experience in all relevant NDT methods.

Whether you need NDT carried out or qualified inspection supervision, we are an experienced and reliable partner at your side. Please contact our team at the W.S. MaterialtestCenter.(opens in new tab)(opens in new tab)