14 Oct Visual Testing in NDT – Course Details And Syllabus

What is Visual Testing ?

Visual testing is also called visual inspection which is one among the oldest and widely used ndt techniques. In this type of testing, the sample is visualised by a trained inspector identifying the flaws directly by using his naked eye or by using mirrors, magnifying glasses, computer-assisted viewing systems and borescopes. Basically the process involved is visual observation of the sample to identify the presence of surface discontinuities like physical damage, cracks, parts misalignment, corrosion etc. This testing can be used not only for the external surface inspection but also for the internal surface inspection of a variety of equipment such as pressure vessels, storage tanks, piping etc. The main advantage in this testing is that a well-trained visual testing inspector can analyse most of the damage signs by visualising the sample or test object.

It also allows to detect deviations of the shape and size from the sample even more than 0.1 mm by using equipment with magnification up to 10x.

The surface of the object should be cleaned from dirt, oil, rust, paint and all sorts of impurities before doing the testing. When compared with other ndt testings, this testing is a reliable and cost effective method of quality control. This type of inspection has less limitations and is widely used for many applications mainly for the flaw detection and the surface flaw interpretation. Basically it can be said that most of the ndt test methods are enhanced visual inspections. Those include Ultrasound testing, Liquid Penetrant testing, Radiography testing, Magnetic Particle testing, Ground Penetrating Radar testing and other test methods that use a skilled version of visual inspection of test results. 

This inspection has many benefits compared to other ndt methods however, this simply cannot get the advanced flaw detection and extensive scanning capabilities of high level NDT equipment. The deficiency in the levels of convenience, efficiency and flexibility of this testing can be overcomed using the Eddy current testing and ultrasonic testing.

Types of Visual Inspection

 Mainly there are two types. They are :-

1. Aided Visual Inspection
2. Unaided Visual Inspection

Aided Visual Inspection

Aided type of inspection is also called Indirect visual Inspection. This inspection is performed with the aid of optical instruments so that it will identify the defects which cannot be detected using the human eye. It allows more visibility to the areas which are not accessible with the human eye alone.

Unaided Visual Inspection

Unaided type of inspection is also called Direct visual Inspection. This can be performed with the use of naked eye. And without the help of other optical aids. Defects like mated parts misalignment, surface porosity, corrosion layer, absence of cracks etc can be identified using this testing.

Equipments or tools used in Visual Testing

•   Magnifying glasses
•   Mirrors
•   Fillet weld gauge
•   Microscopes, Borescope and Endoscope
•   Flexible fibres
•   Computer enhanced systems 
•   Illuminated magnifier
•   Inspection glass
•   Closed circuit television systems

Applications 

• Buildings – Steel and Concrete
• Castings, Forgings
• Bridge Inspection
• Pipe and Pipelines
• Storage Tanks
• Weldments
• Power Plants

Advantages and limitations of Visual Testing

Advantages

• Less cost
• Quick results
• Less advanced skills required
• Easily portable equipment 
• Minimum part preparation
• Simple method 
• Minimal equipment

Limitations

• Is suitable only for surfaces than can be viewed
• Scratches can be confused with cracks 
• Training required for inspector
• Only larger defects can be detected
• Human error possibilities are there
• Quality of the inspection is dependent on the physical conditions, surface conditions etc
• Good eyesight required
• Internal defects may not be identified

Enroll for preparatory classes for ASNT level 2 and 3 Visual Testing Certification

Gamma NDT academy offers NDT preparatory classes for candidates who intend to appear for the ASNT Level 2 and 3 Visual Testing certification exam and also provides certification in QC course in Kerala. 

We will cover all the syllabus under ASNT for Visual Testing and conduct mock tests to prepare you best for the certification exam. We will also share study materials and sample questions which you need to revise. We have a 100% success rate for NDT level 2 and 3 certification courses.

Gamma NDT academy training institute is located in Kerala, India. We provide online classes for candidates who cannot attend our training sessions in-person. Gamma NDT academy is well known for the NDT level 2 course and NDT level 3 course in India.