Visual Testing

Visual Testing (VT) is the most widely used non-destructive testing (NDT) method and is typically the first method applied to any component or weld. This lesson introduces VT within the context of SNT-TC-1A employer-based certification and ISO 9712 requirements. You will learn what VT is, why it is essential in quality assurance, and how the certification and documentation framework applies to visual inspection personnel. This lesson establishes the foundation for all subsequent VT lessons by defining the method, its applications and the responsibilities of certified personnel at each qualification level. Topics: Introduction to Visual testing, Certification Framework, Direct VT Requirements. Learning outcomes include: Define visual testing and explain its role as the first-line NDT method.; Distinguish between general, direct, and remote visual testing.; Describe the certification framework for VT personnel.; Explain the responsibilities of VT Level I, Level II, and Level III personnel..

The effectiveness of visual testing depends fundamentally on the human visual system. This lesson examines the anatomy and physiology of the eye, how vision works, common vision deficiencies, and the visual acuity requirements for VT personnel. Understanding these factors is essential because VT reliability is directly linked to the inspector's visual capability and the conditions under which they work. Topics: Eye Anatomy and Function, Vision Limitations, Fatigue and Performance Factors, Vision Testing Requirements. Learning outcomes include: Describe the basic anatomy of the human eye and the path of light through the visual system.; Explain the functions of rods and cones and their importance to VT.; Identify common vision defects (myopia, hyperopia, astigmatism, presbyopia) and their effects on inspection.; Describe how adaptation, accommodation, and perception affect visual inspection..

Lighting is one of the most critical factors in visual testing. Without adequate and appropriate illumination, even the most skilled inspector cannot reliably detect discontinuities. This lesson covers the physics of light, photometric measurements, light sources, and practical lighting techniques for VT. Understanding these principles ensures that lighting meets procedure requirements and maximizes detection probability. Topics: Light Fundamentals, Lighting Techniques, Code Requirements, Light Measurement. Learning outcomes include: Describe the nature of light and its position in the electromagnetic spectrum.; Define and use photometric quantities (lumens, candela, lux, footcandles).; Apply the inverse square law and Lambert's cosine law to estimate illumination.; Compare common light sources and their applications in VT..

The reliability of visual testing depends on much more than just the inspector's eyesight and lighting. This lesson examines the three main categories of factors that influence VT results: material attributes, environmental conditions, and physiological factors. Understanding these factors enables VT personnel to recognize potential limitations and take appropriate measures to ensure reliable inspection. Topics: Material Attributes, Environmental Factors, Physiological Factors, Viewing Geometry. Learning outcomes include: Describe how surface condition affects VT sensitivity.; Explain how specimen geometry, size, and temperature influence inspection strategy.; Identify environmental factors that affect VT quality.; Describe physiological factors that influence inspector performance..

This lesson covers the optical principles that underpin visual testing equipment. Understanding how lenses form images, how magnification works, and how fibre optics and electronic sensors capture and transmit images enables VT personnel to select and use equipment effectively. This knowledge is essential for understanding the capabilities and limitations of magnifiers, borescopes, and video inspection systems. Topics: Basic Optics, Magnification, Fiber Optics, Magnification Verification. Learning outcomes include: Describe how converging and diverging lenses focus light.; Apply the thin lens equation and calculate magnification.; Explain how fibre optics transmit light and images.; Describe the function of CCD/CMOS sensors in video inspection systems..

This lesson covers the equipment used for both direct and remote visual testing. VT personnel must be able to select appropriate equipment, use it correctly, and understand its capabilities and limitations. This includes lighting equipment, mirrors, magnifiers, measuring tools, weld gauges, borescopes, and video inspection systems. Topics: Direct VT Equipment, Measurement Tools, Remote VT Equipment, Equipment Requirements. Learning outcomes include: Select appropriate equipment for direct and remote visual testing.; Correctly use mirrors, magnifiers, rules, callipers, and micrometres.; Correctly use weld gauges for fillet and groove weld inspection.; Describe the types and applications of borescopes and video systems..

This lesson focuses on the types of discontinuities that visual testing can detect their causes, typical locations, and visual appearance. Understanding how discontinuities form and where to expect them is essential for effective inspection. VT personnel must be able to recognize surface anomalies, distinguish between different discontinuity types, and understand their significance. Topics: Discontinuity Classification, Casting Discontinuities, Weld Discontinuities, Service-Induced Discontinuities. Learning outcomes include: Classify discontinuities as inherent, processing or service induced.; Describe common casting, forging, and weld discontinuities.; Identify typical weld discontinuities and their visual characteristics.; Recognize machining discontinuities and service-induced damage..

This final lesson brings together all previous content and focuses on evaluation, acceptance criteria, procedure development, and documentation requirements. These topics are critical for compliance and represent key responsibilities of VT Level II personnel. You will learn how to evaluate indications against acceptance criteria, develop VT procedures and complete inspection records properly. Topics: Evaluation and Disposition, Reference Standards, Work Instruction Requirements, Record Requirements. Learning outcomes include: Define evaluation and disposition in visual testing.; Identify sources of acceptance criteria (codes, standards, specifications).; Describe common weld acceptance criteria.; Apply remote VT comparison standard requirements..

Scored assessment for Visual Testing. Covers the LMS lesson content for this course.