Radiographic testing is one of the required NDT methods that uses x-rays or gamma rays to view the internal structure of the component. 

We can also say that it is an NDT (Nondestructive Testing) method that involves penetrating X or gamma radiation to examine objects having imperfections. We obtain the results on a radiograph. The radiograph is a record of the radiation transmitted through the object.

You all might know about radiographic testing, its methods, instruments used, etc. Here, we will discuss the types of radiography used as a part of the oil and gas courses for mechanical engineers.

Types of Radiography – an Overview

There are many different RT methods, such as traditional radiography and other types of digital radiographic testing. Each testing method operates a little differently and has its own set of benefits and drawbacks.

Let’s check the different radiography types as a part of online course for piping engineering.

Conventional Radiography

Conventional radiography captures a picture of the part being examined by using a sensitive film that responds to the released radiation. After that, you may inspect the image for signs of damage or defects. 

The most significant drawback of this method is that you can use films only once, and the processing and interpretation take a long time.

Digital Radiography

Digital radiography, unlike traditional radiography, does not require film. Instead, it employs a digital detector to display radiographic pictures on a computer screen instantly. It allows for a significantly shorter exposure period, allowing for faster interpretation of the pictures. 

Furthermore, as compared to conventional radiography pictures, digital images are of far more excellent quality.

The oil and gas industry majorly utilities these 4digital radiography methods: –

Computed Radiography

Computed radiography (CR) uses a phosphor imaging plate instead of a film used in conventional radiography techniques.

This method is faster than film radiography but not as fast as direct radiography. In comparison to direct radiography, CR necessitates many additional procedures.

The initial step involves capturing the image of a component on a phosphor plate and then converting the image into a digital signal that can be visualized on a computer monitor.

The image quality is adequate, but you can improve it with the correct equipment and approaches (i.e., adjusting contrast, brightness, etc., without compromising integrity). 

Care should also be taken to ensure that minor flaws are not hidden when improvements are implemented.

Direct radiography

Direct radiography (DR) is a type of digital radiography that is closely related to computed radiography. The fundamental distinction is in how the picture is recorded. In DR, a flat panel detector is used to record an image immediately and show it on a computer screen. 

Although this technology is faster and produces better pictures, it is more expensive than computed radiography.

Real-time radiography

Real-time radiography (RTR), as the name implies, is a type of digital radiography that takes place in real-time. RTR functions via emitted radiation through an object. These rays subsequently interact with a customized phosphor screen, or a flat panel detector equipped with micro-electronic sensors.

 The interaction of the panel and the radiation results in the formation of a digital image that can be viewed and studied in real-time.

Images generated using RTR frequently have inconsistent lighting, low resolution, a lack of sharpness, and noise. These elements have a significant influence on image quality.

Computed Tomography

Computed tomography (CT) is a method that superimposes hundreds to thousands (depending on the size of the component) of 2D radiography scans to generate a 3D radiographic picture.

CT may be accomplished in two methods in an industrial context. The component to be inspected remains stationary in one method, while the radiation source and x-ray detector revolve around it. 

This method is more likely to be used with large components. The second approach involves keeping the radiation source, and x-ray detector fixed while rotating the component 360 degrees. 

When the component is tiny or has a complicated shape, the second approach is more beneficial.

Even though this technique is time-consuming, costly, and necessitates a considerable quantity of data storage, CT delivers highly accurate pictures, is consistent and reproducible, and decreases human error.
These are the four significant types of radiography that you must know as a part of oil and gas training courses online. When you apply these strategies in the field, you will get remarkable results if you thoroughly understand the subject.