Elbow welding process requirements are very high, if there are problems in the composition of the welding, HI seriously affects the quality of the product, so from what aspects to elbow welding quality inspection? The following Jiaco copper tube Xiaobian for everyone to popularize science.
Jiake copper pipe "popular science" elbow welding quality inspection
The quality inspection aspects of elbow welding are as follows:
1, appearance inspection: generally to the naked eye observation, sometimes with 5-20 times the magnifying glass for observation. Through the appearance inspection, it can be found that the welding elbow weld surface defects, such as undercut, welding nodules, surface cracks, pores, slag and welding penetration, etc. The outer dimension of the welding seam can also be measured by the welding seam detector or the template.
2. Nondestructive inspection: inspection of defects such as slag inclusion, pores and cracks hidden in the welding seam. At present, X-ray inspection is commonly used, as well as ultrasonic inspection and magnetic inspection.
X - ray inspection is the use of X - ray weld photography, according to the negative image to determine the internal defect, defect number and type. And then according to the technical requirements of the product to assess whether the weld is qualified.
The ultrasonic beam is emitted by the probe and transmitted into the metal. When the ultrasonic beam is transmitted to the metal and air interface, it is refracted through the weld. If there is a defect in the weld, the ultrasonic beam is reflected off the probe and accepted, at which point the reflected wave appears on the screen. The size and location of the defect can be determined by comparing and differentiating these reflected waves with the normal waves.
Ultrasonic flaw detection is much simpler than X - ray, so it is widely used. But ultrasonic inspection often can only be judged by operating experience, and can not leave the inspection basis. For internal defects not deep from the weld surface and very small cracks on the surface, magnetic inspection can also be used.
3. Water pressure test and air pressure test: for the pressurized vessels requiring tightness, water pressure test and/or air pressure test shall be carried out to check the tightness and pressure bearing capacity of the weld. The method is to inject 1.25-1.5 times the working pressure of water or gas equivalent to the working pressure (mostly with air) into the container, stay for a certain time, and then observe the pressure drop in the container, and observe whether there is leakage phenomenon outside, according to these can be assessed whether the weld is qualified.
4, the mechanical properties of the elbow test: non-destructive testing can find the inherent defects of the weld, but it can not explain how the mechanical properties of the metal in the heat affected zone of the weld, so sometimes for the tensile force, impact, bending and other tests of the welded joint. These tests are performed on test plates. The test board had better be welded together with the longitudinal seam of the cylinder to ensure the same construction conditions. The mechanical properties of the test plate are then tested. In the actual production, the welding joint of new steel is generally tested in this respect.