Appearance inspection: the general visual observation to the main, sometimes with 5-20 times the magnifying glass to observe. Through the appearance of inspection, can be found in the weld elbow surface defects, such as undercut, welding tumor, surface cracks, pores, slag and welding and so on. The dimensions of the weld can also be measured using a weld detector or model.
Damage detection: detection of hidden in the weld within the slag, pores, cracks and other defects in the test. The most common use is the use of X-ray inspection, as well as ultrasonic testing and magnetic flaw detection. X-ray inspection is the use of X-ray photographic photography, according to the film image to determine whether the internal defects, defects and type. And then according to product technical requirements to assess whether the weld qualified. The basic principle of ultrasonic flaw detection as shown below. The ultrasonic beam is emitted by the probe and is transmitted into the metal. When the ultrasonic beam passes through the metal and air interface, it refracts through the weld. If there is a defect in the weld, the ultrasonic beam is reflected to the probe and is accepted, and the reflected wave appears on the screen. According to these reflected waves and normal wave comparison, identification, you can determine the size and location of defects. Ultrasonic flaw detection is much simpler than X-ray photography, and thus widely used. But the ultrasonic flaw is often only by operating experience to make judgments, and can not leave the test basis. For the surface of the weld from the deep internal defects and very small cracks on the surface, but also the use of magnetic flaw detection.
Water pressure test and air pressure test: For the requirements of the sealed pressure of the container, to be hydrostatic test and / or air pressure test to check the seal of the weld and pressure capacity. The method is to inject 1.25-1.5 times the working pressure of water or equal to the working pressure of the gas (most of the air), stay for a certain time, and then observe the pressure drop in the container, and observe whether the external leakage phenomenon , According to these assessable welds are qualified.