Published on 09-Feb-2024

Types of Visual Inspection

Types of Visual Inspection

Sources - Global Welding Technology

Table of Contents

  • Introduction
  • What is Visual Inspection?
  • Different Types of Visual Inspection
  • How can Drones help with Visual Inspections?
  • What are the benefits of Visual Inspection?
  • Conclusion


The history of inspection is a narrative of human ingenuity and the quest for quality assurance across diverse domains.

In ancient times, civilizations such as the Egyptians and Greeks employed visual inspection techniques to assess the structural integrity of monumental constructions like the pyramids and temples.

As industrialization burgeoned, especially during the Renaissance and the subsequent periods, the need for more sophisticated methods became apparent.

This led to the gradual emergence of Non-destructive Testing (NDT), a revolutionary approach that allowed scrutiny without compromising the integrity of the materials.

In the Oil and Gas Industry, where safety and reliability are paramount, NDT testing took center stage.

The exploration of Ultrasonic Testing brought forth a method relying on sound waves, enabling inspectors to delve into the hidden intricacies of materials, identifying flaws that might escape visual scrutiny.

Simultaneously, Magnetic Particle Testing became a pivotal tool, particularly in assessing the integrity of metallic components crucial to the industry.

The Scaffolding that supports the modern industrial landscape, both figuratively and literally, further underscores the need for rigorous inspection.

Complemented by Advanced NDT Techniques, visual inspection ensures that the scaffolding itself, a linchpin in construction and maintenance, meets stringent safety standards.

This historical journey, from ancient Visual Inspections to the contemporary amalgamation of ultrasonic and magnetic particle testing, represents a testament to the evolution of inspection practices — a narrative driven by the relentless pursuit of precision, reliability, and safety in the intricate tapestry of engineering.

What is Visual Inspection?

Visual inspection is a method in Non-destructive Testing (NDT), that relies on the human eye to assess the surface conditions of materials, structures, and components.

This method involves a structured methodology to ensure comprehensive scrutiny. 

Operators conducting Visual Inspections follow a systematic approach, beginning with thorough planning and preparation.

1. Visual Inspection Methodology

Visual inspection, a key NDT Method, relies on the human eye for a comprehensive examination of surface conditions, ensuring a nuanced understanding of the inspected object.

The approach is structured, adhering to industry standards such as ASNT SNT-TC-1A and ISO 9712, involving meticulous planning and preparation to meet the requirements of a thorough inspection process.

Various Inspection Tools, including flashlights, mirrors, magnifying glasses, and borescopes for confined spaces, are employed strategically during visual inspection, enhancing the inspector's ability to identify and evaluate surface irregularities.

2. Operator Skills and Requirements

In the realm of Visual Inspection, the inspector's proficiency is defined by the possession of a keen eye, an essential skill for identifying subtle surface irregularities and defects during the examination process.

The visual inspection process demands a high level of attention to detail, ensuring that the NDT Inspector can identify and assess even the smallest imperfections on the surface being examined.

Certification in visual inspection is crucial for ensuring the competence and reliability of NDT personnel.

Certifications and Industry Standards provide a standardized benchmark for employers to assess the qualifications of individuals performing visual inspection tasks.

Certified individuals are expected to adhere to industry best practices, contributing to the overall quality and integrity of inspection processes.

3. Industry Standards

  • ASNT SNT-TC-1A (American Society for Non-destructive Testing Recommended Practice No. SNT-TC-1A):

This standard is widely recognized and provides guidelines for the Qualification and Certification of NDT personnel, including visual inspectors.

It outlines the requirements for the training, experience, and examination of individuals involved in Visual Inspection.

ASNT SNT-TC-1A is often adopted by industries to ensure a consistent and reliable approach to NDT personnel qualification.

  • ISO 9712 (International Organization for Standardization):

ISO 9712 is an international standard that specifies requirements for NDT Personnel Certification, including a visual inspection.

It provides a framework for the qualification and certification of personnel involved in various NDT Methods, ensuring a global standardization of practices.

ISO 9712 certification is recognized worldwide, emphasizing the importance of adherence to consistent inspection practices across borders.

4. Certifications

  • Qualification Process:

Individuals seeking certification in Visual Inspection typically undergo a comprehensive qualification process.

This process involves a combination of formal classroom training, practical hands-on experience, and the successful completion of examinations.

The aim is to ensure that certified individuals possess the knowledge, skills, and proficiency required for effective visual inspection.

  • Visual Inspection Certifications:

Certifications in visual inspection may have different levels, such as Level I, II, and III, each representing a progressive level of expertise.

Level I: Entry-level certification indicating basic proficiency and the ability to perform Visual Inspection under direct supervision.

Level II: Intermediate certification indicating a higher level of proficiency, allowing for more independence in performing visual inspection tasks.

Level III: Advanced certification indicating expertise in visual inspection, often involving responsibilities such as procedure development, training, and supervision.

Different Types of Visual Inspection

Visual Inspection provides freedom and adaptability to the operator and industry compared to some Advanced NDT Methods.

A wide range of materials, equipment, and structures can be tested using Visual Inspection, especially when carried out by a trained inspector.

The different types of Visual Inspection include the following methods:

1. Direct Visual Inspection:

This method involves the direct visual examination of an object's surface using the naked eye or basic Inspection Tools.

This technique is widely used in various industries for routine inspections, Weld inspections, and structural assessments.

This method can be used to detect visible surface defects, weld discontinuities, corrosion, and other anomalies that can be identified by visual observation.

2. Microscopic Inspection:

Microscopic Inspection utilizes microscopes or magnifying tools to inspect surfaces at a microscopic level.

This method is commonly applied in electronic and semiconductor industries for examining small components and intricate details.

Subsurface cracks, microscopic flaws, and other minuscule defects can be detected using microscopic inspection that may otherwise not be visible to the naked eye.

3. Magnetic Particle Inspection (MPI):

Magnetic Particle Inspection involves the application of magnetic fields and magnetic particles to identify surface and near-surface defects.

This testing technique is commonly used in the inspection of ferromagnetic materials such as steel.

Surface cracks, weld discontinuities, and other defects interrupt the magnetic field and attract magnetic particles.

4. Liquid Penetrant Inspection (LPI):

This method involves applying a liquid penetrant to the surface, which penetrates surface-breaking defects.

The excess penetrant is then removed, and a developer is applied to make the defects visible.

Liquid Penetrant Inspection is suitable for non-porous materials and widely used in aerospace, automotive, and general manufacturing.

This method permits the detection of surface cracks, porosity, and other open-surface defects that allow the penetrant to enter. This method is also known as liquid penetrant testing (LPI).

Each of these Visual Inspection methods plays a crucial role in Non-destructive Testing (NDT), offering specific advantages and applications in different industries.

The incorporation of visual inspection automation and remote visual inspection, including the use of drones for Visual Inspection, has enhanced the efficiency and accessibility of these methods.

How can Drones help with Visual Inspections?

Utilizing drones for Visual Inspection enhances accessibility to remote or challenging environments.

Drones equipped with cameras facilitate efficient and comprehensive inspections.

Drones offer cost-effective solutions, reducing the need for traditional, time-consuming, and resource-intensive inspection methods.

For example, the Autel Robotics EVO Lite+ series is known for its high-resolution cameras, enhancing the quality of visual inspections.

1. Enhanced Accessibility

Drones can access difficult-to-reach or hazardous areas, providing a safe and efficient solution for inspections.

Drones such as the Phantom 4 RTK, from the DJI Phantom series are commonly used for their agility and stability. 

2. Visual Inspection Automation

Visual Inspection automation involves programming drones to follow predefined flight paths, ensuring thorough and consistent inspections.

The Flyability Elios 2 is a drone designed for confined spaces, allowing automated inspection in complex environments.

3. Remote Visual Inspection

Drones enable inspectors to remotely assess structures, Pipelines, or equipment, reducing the need for physical presence.

An example of such technology is the DJI Matrice 300 RTK, which is an enterprise-grade drone with advanced capabilities for remote visual inspection.

4. Visual Inspection for Welding

Drones equipped with high-resolution cameras facilitate close-up inspections of welds, ensuring quality and identifying defects.

For example, the Elios 2 can be used for Visual Inspection of welds in confined spaces or areas with limited access.

5. Integration of AI in NDT

AI-powered drones like the Skydio X2D leverage Artificial Intelligence for autonomous navigation and obstacle avoidance.

AI algorithms enhance visual inspection by automatically analyzing images for defects or anomalies, improving the efficiency of NDT processes.

6. Visual Inspection Equipment and Tools

Visual inspection equipment on drones may include cameras, thermal sensors, and other specialized tools to capture detailed data during inspections.

The DJI Mavic 2 Enterprise Dual is a drone that is equipped with thermal imaging capabilities for enhanced inspection.

NDT Professionals can utilize drones to enhance their capabilities, offering a new dimension to the inspection process.

Drones can be employed in conjunction with different NDT Methods, providing a flexible and adaptable solution.

What are the benefits of Visual Inspection?

The advantages of Visual Inspection include the following:

  • Cost-Effective

Visual Inspection is often more economical compared to advanced methods like ultrasonic testing, magnetic particle testing, and Liquid Penetrant Testing.

  • Real-Time Adaptability

Visual inspection allows for immediate on-site assessments, contributing to real-time decision-making during the inspection process.

  • Versatility

Applicable to a wide range of materials and structures, making it a versatile choice for diverse industries.

  • Integrating Automation

Visual Inspection automation enhances efficiency by automating repetitive tasks and ensuring consistent and thorough inspections.

  • Drone Accessibility

Drones facilitate Remote Visual Inspection, reaching challenging or hazardous areas, and reducing the need for manual intervention.

  • Efficient Use of Visual Inspection Equipment

The use of specialized visual inspection equipment like cameras and scopes enhances the inspector's ability to identify defects and anomalies.

  • Complementary to Other NDT Methods

Visual inspection complements Advanced NDT Methods, providing a comprehensive assessment when used in conjunction with techniques like ultrasonic testing and magnetic particle testing.


Visual Inspection remains a foundational and enduring method in non-destructive testing (NDT).

As we witness the integration of automation, AI, and robotics, particularly in visual inspection automation and Drone Inspection, the landscape of NDT is evolving.

These advancements enhance efficiency, safety, and accuracy, especially in inaccessible or adverse conditions. 

The incorporation of AI in NDT, coupled with Visual Testing and drone inspection, emphasizes the transformative nature of these technologies.

Visual inspection's simplicity, accessibility, and role as the initial step in identifying defects ensure its continued relevance, complementing Advanced NDT Methods applied by professionals and technicians in the field.

Key Takeaways

  • Visual Inspection remains a foundational and accessible method, serving as the initial step in defect identification and complementing advanced NDT methods applied by professionals in the field.
  • Integration of automation, including Drone Technology and AI/ML algorithms, enhances efficiency, accuracy, and safety in Visual Inspection.
  • Visual inspection offers a range of methods, from direct visual examination to microscopic inspection and specialized techniques like Liquid Penetrant Testing and magnetic particle inspection, making it adaptable to diverse materials and structures.


1. What are the Visual Inspection Methods?

A: Visual inspection methods encompass a variety of techniques, including direct visual examination, microscopic inspection, liquid penetrant testing, Magnetic Particle Testing, and other specialized approaches, ensuring a comprehensive assessment of materials and structures in various industries.

2. What is another name for visual inspection?

A: Visual inspection, also known as Non-destructive Testing (NDT), is colloquially referred to as the "Eyeball" technique. 

The act of performing visual inspection is often informally termed "eyeballing," highlighting the reliance on visual observation in this method.

3. What are the 3 main types of inspections?

A: The three principal types of inspections crucial in non-destructive testing (NDT) are visual inspection, Ultrasonic Testing, and magnetic particle testing.

Each method serves specific purposes, contributing to the thorough assessment of materials and structures, particularly in industries such as oil & gas and Scaffolding.

4. What type of test is visual inspection?

A: Visual inspection stands as a significant type of Non-destructive Testing (NDT), employed to assess the integrity of materials and structures without causing damage.

Its versatility and accessibility make it a fundamental component in various industries.

5. What are the different types of visual inspection in an aircraft?

A: In the aircraft industry, Visual Inspection methods play a pivotal role, encompassing a range of techniques.

These include routine visual inspections, Ultrasonic Testing for critical components, and liquid penetrant testing for detecting surface defects.

These methods, crucial for maintaining safety and reliability, demonstrate the diverse applications of visual inspection in the aerospace sector.


1. Power-MI

2. Olympus IMS

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