Radiographic inspection is a nondestructive testing technique used to evaluate objects and components for signs of flaws which could interfere with their function. It is accomplished with the use of radiographs, images generated by bombarding the object under inspection with radiation. X-ray and gamma ray radiographic inspection are the two most common forms of this inspection technique. Materials testing companies often offer radiographic inspection to their clients, and some companies have their own inspection facilities for in-house inspections.
In film radiographic inspection, the object is mounted in a manipulator with sensitized plates behind it. X-ray or gamma ray radiation is aimed at the object, and the plate is exposed by the radiation which passes through the object. Once developed, the plate reveals an image of what is going on inside the object, in very precise detail. This can be used to identify flaws such as cracks, thickness variations, inclusions, bubbles, bad welds, and so forth.
The disadvantage to using film is that it takes time. Sometimes, companies prefer to use real time inspection, in which the radiographic image is displayed on a monitor as a device is moved over the object being inspected. This method tends to have less clear resolution, and it doesn't create a permanent record like film does unless the real time inspection is recorded, as is done in some cases. The advantage is that it can be done very quickly, which can be key during rapid inspection and repair.
Inspection radiography may be required by law for safety reasons, or a company may opt for using this technique to assure that their products are of high quality. The nondestructive nature is also an advantage, as radiographic inspection can be used to evaluate things quickly without needing to disassemble them or damage them in the process. For example, when airlines inspect aircraft components such as landing gear, radiographic inspection can be used to look inside to confirm that the components are in good working order.
Special precautions need to be followed when performing radiographic inspections, because people can be harmed by the exposure to radiation. People and devices need to be adequately sealed, and the inspection area must be clearly marked with warnings so that people understand that a radiation risk is present. It's also important to follow the protocol established for safety, using the radiographic inspection equipment as directed and with all safety features operational and working.