Visual Inspection, Part 2

This is a new series of articles put together by the Practitioner Committee to describe the principles of different NDT methods and techniques as an introduction to practitioners...

Part 1 of this article, published in the June 2021 issue of NDT News, introduced visual inspection and detailed the difference between a Visual Inspector of Welds and a Welding Inspector. In Part 2, we review the certification requirements for both visual inspection and weld inspection and compare the subjects covered in the syllabuses for the two methods.

Visual inspection certification requirements In the past, visual inspection has been conducted by personnel with different work experiences. These include: NDT operators holding certification in other methods, such as magnetic particle inspection or penetrant testing, who have had some training on the type of surface defects that may occur; dimensional inspectors, who will visually inspect the surface of the component as part of the dimensional inspection; and individuals specifically trained by the employer to conduct visual inspection on specific parts and components.
Many of the practitioners who undertake visual training and certification exams have some experience of visual inspection. They may already hold certification in other NDT methods and they may have experience of inspecting certain product types, for example welds, but very rarely have personnel got experience in the complete range of product types.
It is important to conduct personnel qualification and certification to^[1]:

Enhance understanding of the technology, principles and practices of visual inspection; and
Ensure the correct use of visual techniques.

In recent years, the need for certified visual inspectors has increased. On many contracts, the requirement for suitably qualified or certified visual inspectors is now mandatory. As a result of these requirements, the demand for training and certification has increased.
Certification schemes may be employer-based, using documents such as ASNT Recommended Practice No SNT-TC-1A or ANSI/ASNT CP189, or alternatively in the aerospace sector NAS 410 internationally or BS EN 4179 in the UK and Europe^[2-5].
Central certification has been developed using standards such as BS EN ISO 9712:2012 ‘Non-destructive testing – Qualification and certification of NTD personnel’^[6].

Employer-based schemes SNT-TC-1A ‘Personnel qualification and certification in nondestructive testing’ provides guidelines for employers and identifies the attributes that should be considered when qualifying NDT personnel. It requires the employer to develop and implement a company written practice, a specific document of the process and any limitations in the qualification and certification of NDT personnel^[2].
ANSI/ASNT CP189 ‘Standard for qualification and certification of nondestructive testing personnel’ resembles SNT-TC-1A but establishes specific mandatory requirements for the qualification of NDT personnel^[3].
These employer-based schemes are flexible and can be developed based around the specific needs of the employer.

Central Certification^[1] The International Organization for Standardization (ISO) produces international standards through technical committees. Technical Committee ISO/TC 135 NDT Sub-Committee SC7, Personnel Qualification prepared international standard ISO 9712 ‘Non-destructive testing – Qualification and certification of NDT personnel’.
PCN NDT certification based in the UK meets or exceeds the requirements of ISO 9712 and is recognised internationally throughout the world^[6].

PCN Visual Inspection^[7] The PCN Scheme offers certification of personnel for visual testing in the pre- and in-service inspection sector and the following certification is available:

Level 1 Visual Testing of general engineering materials, components and fabrications in the pre- and in-service inspection multi-sector;
Level 2 Visual Testing of general engineering materials, components and fabrications in the pre- and in-service inspection multi-sector;
Level 3 Visual Testing of general engineering materials, components and fabrications in the pre- and in-service inspection multi-sector.

Alternatively, Level 1 and Level 2 candidates may apply for single-sector certification covering one (only) of the following groups:

Castings
Welds
Wrought products.

Anyone considering undertaking visual inspection training and certification exams should not underestimate the extent of the syllabus. Training courses based on ISO 9712 (PCN in the UK) use ISO/TS 25107^[8] to identify the syllabus requirements for all NDT methods and a summary of the extensive visual inspection syllabus is shown in Table 1.

Table 1. Summary of the syllabuses for both visual inspection and weld inspection, identifying the differences in subject matter between the two disciplines

PCN visual testing syllabus	PCN weld inspection syllabus
Introduction to terminology and history of visual testing (VT) History; Purpose of NDT; Purpose of visual testing (VT); Terminology	Introduction
Physical principles and associated knowledge Fundamentals; Vision; Lighting; Optical principles; Camera and photo sensor operation and principles; Principles of operation of fibre bundles and lenses; Photogrammetry; Visual perception; Material attributes affecting the test; Environmental and physiological factors; Direct and remote methods	Principles of weld inspection Duties prior to welding; Duties during welding; Duties after welding; Visual testing of finished weld; Reporting of weld; Monitoring of any weld repairs required
Product knowledge and related capability of the method and derived techniques Capability and limitations of visual testing; Associated techniques	Welding imperfections Imperfection acceptance levels Planar imperfections; Gas inclusions; Solid inclusions; Workmanship imperfections; In-service imperfections; Cracks
Equipment Introduction and applications; Photographic and video; Image recording transfer and storage equipment; Sizing of indications	Welding equipment Construction and mode of operation of welding equipment; Block diagram of welding processes; Welding current and type of polarity; Calibration and validation of equipment; Health and safety of equipment
Information prior to test Information about the test object; Test conditions and application of standard; Technique and sequence of performing; Test; Instructions	Weld joint design Weld joint terminology; Types of joint; Weld zone terms; Welding position; Weld symbols
Testing Test set-up	Welder testing Witness welder qualification test
Evaluation and reporting Reporting results; Control and monitoring of test results	Welding procedure qualification Witness of welding procedure qualification test
Quality aspects Personnel qualification; Documentation; Knowledge of applicable NDT application and product standards	Materials: properties and weldability Typical ‘steel’ composition: elements and properties; Grain structures; Heat-affected zone; Hydrogen; Carbon equivalent; Heat treatments Various metals, steel types and a guide to weldability; Residual stress and distortion
Developments	Welding consumables Applicable codes and standards; Consumable by process: SMAW; Classification of consumables; Storage and handling
–	Thermal cutting Flame cutting processes and their effects; Electric arc cutting processes; Non-thermal cutting methods and effects
NDT Knowledge of applicable NDT application and product standards	NDT Understanding of main NDT methods (testing of welds)
Quality aspects Personnel qualification; Documentation	Quality control / quality assurance Quality assurance; Scope of quality assurance; Normative documentation
–	Safety Protection against heat and light; Protection against electrical shock; Protection against fumes and gases; Ergonomics in the welding environment; Tungsten electrodes

Weld inspection certification requirements Weld inspection is a fundamental part of the manufacture of fabricated products to ensure consistent performance. Both PCN and CWSIP have similar certification schemes in the UK for weld inspection but are outside the scope of ISO 9712.

PCN Weld Inspector certification^[9] The following certification is available:
Level 1 Welding Inspector
The Level 1 Welding Inspector is aimed at personnel coming into welding inspection for the first time with a limited scope of work and being supervised by a Level 2 or Level 3 Welding Inspector. The Level 1 will assess and visually accept or reject welded joints. The Level 1 Inspector will, however, have limited exposure to before and during welding activities and will report their findings to the Level 2 or 3 for sentencing. A significant part of this level concentrates on aspects of visual testing of welds in accordance with BS EN ISO 17637 requirements.
Level 2 Welding Inspector
The Level 2 Welding Inspector has an increased scope of duties and competencies compared to a Level 1 Welding Inspector and includes a greater emphasis on pre-weld inspection of joints and their correct fit-up against the welding procedure specification.
Level 3 Welding Inspector
The Level 3 Welding Inspector shall be able to perform, and more importantly supervise and when required mentor, Level 1 and 2 Welding Inspectors as part of a continuous improvement philosophy. The Level 3 shall oversee the correct application of NDT by competent inspection personnel and prepare inspection procedures and test plans and review and interpret welding procedures as required, while working closely with the welding engineer or welding coordinator. The Level 3 Welding Inspector shall also be involved with the conduct of audits of vendors and/or organisations providing services or materials to the project and ensure that the work is performed to, and the records kept are in accordance with, the contract requirements and the applicable codes and standards.

CSWIP Weld Inspection certification^[10] For CSWIP, weld inspection certification is available as follows: Visual Welding Inspector; Welding Inspector; and Senior Welding Inspector.
Typical areas of work activity of personnel for whom CSWIP welding inspector certification is relevant are as follows:

Visual Welding Inspector

Post-weld visual inspection: visual inspection and dimensional check of completed weld against specification and drawing requirements and under the supervision of a Welding Inspector or Senior Welding Inspector:
Establish the most suitable welding processes;
Codes and standards: application of the requirements of codes and standards;
Parent material identity: verification against documentation and marking of correctness of parent material;
Welding consumables identity: verification of correctness of welding consumables (electrodes, filler wires, consumable inserts, gases, fluxes, etc);
Pre-weld inspection: verification that dimensions, fit-up and weld preparations are in accordance with the engineering drawings;
Preheating: verification that preheat (where required) is in accordance with specified procedures;
In-process welding surveillance: surveillance during welding to verify compliance with the specified procedure, including any preheat, interpass temperature control and post-heat requirements.

Welding Inspector

Supervision of visual weld inspectors in the conduct of activities (b) to (h);
Welding procedures: establishing that a procedure is available, has been approved as required by the appropriate authority and is being employed in production;
Witnessing of welder and procedure approval tests: witnessing the preparation of test-pieces and destructive tests are available and verifying compliance with appropriate standards and specifications;
Welder approvals: verification that adequate and valid welder approvals are available and that only approved welders as required are used in production;
Post-weld heat treatment: verification that post-weld heat treatment has been conducted in accordance with specification requirements;
Reports: preparation of test reports.

Senior Weld Inspector

Supervision of welding inspectors and visual welding inspectors in the conduct of activities (b) to (n) above as appropriate;
Certification of compliance: final acceptance and certification that the requirements of the specification have been met;
Weld drawings;
Interpretation of weld drawing and symbols;
Weld defects: identification of weld defects and determination of their acceptability in relation to the specification;
NDT results: verification of NDT reports on welding work for which the senior weld inspector is responsible. This may include radiographic interpretation;
Quality assurance: ensuring the quality assurance standards and procedures are being maintained.

References

ASNT Nondestructive Testing Handbook, Volume 9: Visual Testing, 3rd edition, 2010.
SNT-TC-1A, ‘Personnel qualification and certification in nondestructive testing’, ASNT, 2020.
ANSI/ASNT CP189, ‘ASNT standard for qualification and certification of nondestructive testing personnel’, 2020.
NAS 410, ‘NAS certification & qualification of nondestructive test personnel’, 2020.
BS EN 4179, ‘Aerospace series – Qualification and approval of personnel for non-destructive testing’, 2017.
BS EN ISO 9712, ‘Non-destructive testing – Qualification and certification of NDT personnel’, 2012.
PCN/GEN APPENDIX E5, Issue 7, Revision A, ‘Certification of personnel for visual testing in the pre- and in-service inspection sector’, January 2016.
PD CEN ISO/TS 25107, ‘Nondestructive testing – NDT training syllabuses’, 2019.
PCN WI_01, Issue 4, Revision 2, ‘Specific requirements for the certification of personnel for weld inspection’, January 2018.
CWSIP-WI-6-92, ‘Requirements for the certification of visual weld inspectors welding inspectors and senior welding inspectors (fusion welding) in accordance with the requirements of BS EN ISO 17637:2016’, July 2021.

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