Advantages of nondestructive testing and X-ray testing of welding quality

Date：2021-08-20 11:16:00Views：1137

Welding quality inspection refers to comparing the welding quality with the use requirements of welding products through investigation, inspection, inspection and test, so as to prevent the continuous production of unqualified products and avoid quality accidents. Generally, the inspection after welding shall include actual welding records, welding appearance and size, post welding heat treatment, product welding test, sheet metal inspection and fracture inspection, nondestructive inspection, pressure test, air tightness test, etc.

The inspection items shall be determined according to the type, working characteristics and importance of welded structure. In principle, the welding inspection methods and scope of various welded structural products shall comply with relevant national standards, production regulations or the provisions of the company's product welding technical conditions. The inspection procedure is specified in the welding procedure specification.

For the welded joints of some structural materials, the NDT procedure is the key link to ensure the welding quality. For example, under some working conditions, the thick wall joints of high-strength steel with yield strength of 460Mpa usually have the tendency of delayed crack caused by hydrogen, so it is required to carry out NDT within 48 hours after welding. Another example: after eliminating the weld stress, the weld with reheat crack tendency shall be reprocessed. For welded structures requiring joint strength and base metal strength, such as boilers, pressure vessels and pipelines, welding test plates for welded products are usually designated to test the mechanical properties, chemical composition, metallographic structure and other properties of the joint.

In fact, this is also a further verification of the welding procedure specification. Compared with the welding procedure qualification test plate, the welding conditions of the finished welding test plate are closer to the actual welding production conditions. If the inspection result is completely qualified, it indicates that the welding process is applicable, continues to be effective and can be reused. In the production of large-scale welded structures, welding test plates of unqualified products often appear. At this time, we should carefully analyze and find out the cause through corresponding tests. In addition to the abuse or misuse of structural materials and welding materials, the main problem is the welding process. If the test results prove that the welding procedure is incomplete, the welding procedure specification shall be modified.

The main advantages of X-ray nondestructive testing are: Volume defect detection is more sensitive and it is easier to determine the defect qualitatively; Radiographs are easy to preserve and traceable; Visually display the shape and type of defect.

Industrial real-time X-ray imaging testing equipment is a nondestructive testing equipment in the field of standardized industry. The technology and equipment are widely used in automobile parts manufacturing (aluminum castings, iron castings, etc.), oil pipeline welding inspection, metal parts, aviation parts, pressure vessels, construction, petroleum, chemical industry, machining, electronics, military and other industries. It has high resolution and excellent inspection image quality. At the same time, it has the functions of defect self-determination and automatic identification, and supports non-standard customization.

Summary: as the importance of welding application increases, the welding cost and the subsequent cost of correcting poor welding execution and poor welding quality also increase. Therefore, it is very important to ensure the welding quality, and weld tracking is the guarantee of welding quality.