X-ray inspection of welded pipe welds

Radiographic inspection technology for steel pipe welds can be broadly classified into two categories: X-ray film imaging and digital imaging. This article will discuss X-ray inspection methods used for evaluating welded pipe joints.

X-ray Inspection Equipment Requirements

Radiographic inspection of steel pipe welds involves the use of X-rays to penetrate the weld material, producing images on either radiographic films or digital media. The required blackness of the radiographic film should be no less than 2.0, with the weld area specifically needing a blackness of at least 1.5. An image quality meter, as specified by ISO standards, is used to match the transillumination thickness, ensuring the sensitivity of the X-ray film is better than 2%. For industrial television systems, dynamic sensitivity should be better than 4%.

Technical Requirements for X-ray Detection:

The evaluation room should maintain a clean and quiet environment with a suitable temperature. Lighting should be dim and soft.

The testing environment must consistently maintain appropriate temperature and humidity levels.

To ensure high-quality film results, strict adherence to proper development, fixing processes, and the use of validated film is necessary.

Regular checks must be conducted to confirm darkroom safety exposure levels.

Applications of X-ray Inspection

X-ray inspection is primarily used to identify volumetric defects in steel pipe welds that may occur during the welding process. These defects include lack of fusion, beads, pores, cracks, incomplete welds, and tungsten inclusions.

Advantages of X-ray Inspection Technology:

The size and shape of defects can be directly observed on the radiographic film.

The test results can be archived for extended periods using the films.

X-ray inspection is particularly effective for detecting volumetric defects, characterized by significant radiation energy attenuation, and for comparing defects based on the blackness differences in the radiographic films.

However, radiographic inspection does have its drawbacks. The process is costly, with radiographic films being single-use and non-reusable. Additionally, detecting area defects is limited by the directionality of the inspection. Given the radiation involved in radiographic flaw detection, it is crucial to implement safety protection measures to ensure worker safety.