What is Visual Inspection (VT)?

Visual Inspection (VT) is a non-destructive testing method that examines the surface of a material or structure using the naked eye or simple auxiliary tools such as a magnifying glass. With this method, surface defects such as cracks, corrosion, and deformations can be observed. Visual inspection is generally a fast, simple, and cost-effective test used as a first step to identify possible problems on the outer surface of a material.

What is the Visual Testing Standard?

Visual testing (VT), as one of the non-destructive testing methods, is performed according to specific standards. These standards are designed to enhance reliability, ensure consistency of results, and regulate quality control processes at an international level.

One of the most widely used standards is the ISO 17637 standard. This standard defines the requirements for the visual inspection of welded joints and details how the inspection procedures should be performed.

It also includes details such as the equipment to be used during inspection, lighting requirements, and defect evaluation criteria.

Among American standards, ASME Section V, Article 9 and AWS D1.1 are frequently referenced for visual testing. These standards specify visual inspection procedures particularly for metal welds and engineering applications.

Lighting conditions are also an important standard element in visual inspection. Typically, a minimum illumination of 500 lux is required on the inspected surface to ensure defects can be properly detected.

The competence of operators is another key component of visual inspection standards. International standards such as ISO 9712 define the training and certification requirements for inspection operators. These certifications guarantee that operators have the knowledge and skills to apply the method correctly and reliably.

Standards improve the accuracy of applications, ensure reliable results, and support international recognition of inspection outcomes.

How is Visual Inspection Performed?

First, the material or structure to be inspected is determined. The suitability of the area where the test will be performed is a key factor for success. A smooth and clean surface helps ensure inspection accuracy.

Although visual inspection is generally carried out with the naked eye, auxiliary tools are sometimes used for more detailed examinations. These may include magnifiers, handheld microscopes, cameras, or telescopic devices. The tool chosen depends on the size and complexity of the inspected surface.

Dirt, oil, rust, or other obstacles on the surface may hinder visual inspection. Therefore, cleaning the surface before inspection is essential. A clean surface allows defects to be seen more clearly.

During the inspection, all details of the surface are carefully examined. Cracks, scratches, corrosion, deformations, welding defects, and any abnormalities are looked for. If a defect is detected, it is typically documented, and corrective actions are initiated.

The findings from the visual inspection are recorded. If a defect or abnormality is detected, the report includes information about the location, type, and size of the defect. This report serves as a reference for corrective actions or further non-destructive tests.

The results are evaluated by engineers or testing specialists. If a significant issue is found, it is typically directed for further non-destructive testing or repair processes.

While visual inspection is a fast and effective method, it can only detect visible surface defects. More advanced testing methods may be required to detect subsurface or internal issues. However, it is an ideal first-step method for quick control and identifying potential problems.

Application Areas of Visual Inspection (VT)

Visual inspection (VT) is an effective non-destructive testing method used to detect surface defects across many industries. It is widely applied in areas such as welded joints, pressure vessels, and pipelines. It is particularly preferred for identifying defects such as cracks, porosity, lack of fusion, undercut, or spatter on welded surfaces. In pressure vessels, cracks, leaks, corrosion, and deformations are checked, while in pipelines, corrosion, surface deterioration, and cracks are detected.

In critical sectors such as aerospace, visual inspection plays a major role in ensuring the safety of aircraft and spacecraft. In this sector, cracks, corrosion signs, or other surface degradations on structural components are examined through visual inspection. Additionally, it is applied in power plants, the automotive industry, and shipbuilding as part of safety, durability, and quality control processes. Due to its ease of use and fast results, it stands out as a reliable evaluation tool across many industries.

Direct and Indirect Visual Inspection

Visual testing (VT) is one of the most basic and widely used non-destructive testing methods. It can be applied through two approaches: direct visual inspection and indirect visual inspection. Both focus on detecting surface defects, but differ in application methods and equipment used.

Direct Visual Inspection:

Direct visual inspection means physically observing the inspected surface with the human eye. In this method, the surface must be accessible and adequately illuminated. The operator examines the surface using the naked eye or a magnifying glass to detect defects such as cracks, corrosion, deformations, or welding flaws. It is simple, economical, and fast. However, it cannot be used when the surface is not directly accessible.

Indirect Visual Inspection:

Indirect visual inspection is used when the surface cannot be directly seen by the eye and requires special equipment. These include endoscopes, borescopes, mirrors, cameras, and fiber optic devices. It is typically applied in confined or hard-to-reach areas.

For example, the inner parts of pipelines, turbine interiors, or aircraft engines can be inspected using indirect visual inspection. The equipment used in this method enables detailed visualization and recording of the surface.

Both methods, when properly applied, yield effective results in detecting surface defects.

The choice of the correct method depends on the surface characteristics, accessibility, and the purpose of the inspection. Visual inspection plays a critical role in process safety, product quality, and durability.

Advantages of Visual Inspection

Visual inspection (VT) is one of the most basic and widely used non-destructive testing methods. Its ease of application, wide range of use, and low cost make it a popular choice in industrial and engineering applications.

One of its main advantages is that it provides immediate and direct results. Surface defects can be instantly detected using the naked eye or simple equipment like magnifiers, mirrors, or lighting tools. Since it doesn’t require complex equipment, it is both cost-effective and time-efficient.

Another major advantage is its broad applicability. Visual inspection can easily be applied in welding operations, cast parts, pipelines, machine components, and more. It can be performed at almost any stage of production, making it a valuable tool for quality control and defect detection.

Visual inspection also offers real-time evaluation capabilities. Since it does not require chemicals or special processing, it is an environmentally friendly method. Moreover, it can be easily performed in the field or in urgent situations with simple tools.

Finally, visual inspection requires less technical knowledge compared to other non-destructive methods. This shortens the training process and allows operators to achieve effective results with basic knowledge. However, the effectiveness of the method depends on the operator’s experience and surface accessibility.

What is an NDT Specialist?

An NDT (Non-Destructive Testing) specialist is a professional who can assess the physical integrity and quality of materials, equipment, or structures without causing any damage. These individuals are knowledgeable in various testing techniques used in industrial applications. They identify defects and reduce safety risks using methods such as Ultrasonic Testing (UT), Radiographic Testing (RT), Magnetic Particle Testing (MT), and Visual Testing (VT).

Why is NDT Necessary?

Non-destructive testing is essential in industrial processes to ensure quality and safety. In sectors such as oil, gas, energy, aerospace, construction, and automotive, the durability of materials and equipment is crucial. The work of NDT specialists helps detect faults in advance, preventing manufacturing errors, environmental hazards, and costly downtime.

Certified NDT Specialist

A certified NDT specialist is an individual who has received training and demonstrated competence in non-destructive testing methods according to specific standards. Certifications are generally internationally recognized and issued in accordance with standards such as ISO 9712, EN 4179, or ASNT. Specialists holding these certificates document their technical knowledge and experience, providing reliability in industrial projects.

Certified NDT specialists not only meet quality control and safety standards in their fields but also provide professional service to clients and enhance competitive advantage within the industry.

Contact Us for Visual Inspection

As Experte, we offer non-destructive testing services in accordance with EN ISO 9712 standards. With our expert team and modern equipment, we provide high-quality and reliable solutions tailored to your industrial needs.

Our visual inspection service is an ideal method to verify the safety, durability, and compliance of your materials and equipment with standards. For detailed information and professional support, please contact us.