The next type of defects monitoring, which we will consider, is based on the sample destruction of the welded joint with notches along the weld. This type of test is used mainly in the pipeline industry and is regulated by the American Petroleum Institute API 1104 standard. This method is based on the evaluation of faultlessness by breaking the sample over the weld and then monitoring the surface for the presence of discontinuities. The break is localized in the welding zone by means of notches on two or three surfaces. The typical sample for fracture testing is shown in Fig.1.
After the cuts are applied to the sample, it is broken in the test machine. At the center of the sample, the ends of which are fixed, hit with the hammer or by fixing one end in the vice, strikes the free end. The very method of destruction does not matter, since we are not interested in the amount of energy that is required to spend on the destruction of the sample. The problem is to break the sample in the weld zone and detect the presence of defects. Then, the fracture surface is inspected for the presence of zones containing slag inclusions, pores or lack of penetration. In the case of detection, the defects parameters are evaluated and the product is accepted or rejected based on the restrictive conditions of the standard.
The last type of defect tests, which we will consider, is called a test by breaking a specimen of a corner weld. Like the previous two types, this method of checking for defects is intended primarily for the certification of welders. This is the only test that is required for the certification of welders-tack welders in accordance with the provisions of the AWS D1.1 standard. After welding, the sample is subjected to dynamic or static loading until the sample is completely destroyed in the welding zone. In this test, the welding inspector must ensure that the surface of the welded joint is in the satisfactory state.
The fracture surface, after fracture of the sample, is checked for signs of complete fusion to the root of the seam, the absence of zones of incomplete fusion with the base metal or pores larger than 3/32 inch.
Such defect tests are used in a variety of different industries. Their practical implementation and evaluation of the results seem quite understandable. However, the welding inspector should be aware that evaluating the results of such tests is not always as simple as it may be due to different norms, rules and technical conditions. Therefore, the welding inspector needs sufficient experience in carrying out such tests and deciphering the results.