Welding inspection content includes the materials, tools, equipment, process, and finished product quality inspection used in the entire production process from drawing design to product manufacturing. It is divided into three stages: pre-weld inspection, inspection during welding, and post-weld Inspection of finished products. The inspection method can be divided into two types: destructive inspection and non-destructive inspection according to whether the product is damaged.
1) Inspection before welding
The pre-weld inspection includes inspection of raw materials (such as base metal, welding rod, flux, etc.), an inspection of welding structure design, etc.
2) Inspection during welding
Including the inspection of welding process specifications, the inspection of weld size, the condition of fixtures, and the quality of structural assembly.
3) Inspection of finished products after welding
There are many methods for inspection of finished products after welding, and the following are commonly used:
(1) Appearance inspection The appearance inspection of welded joints is a simple and widely used inspection method. It is an important part of finished product inspection, mainly to find defects and dimensional deviations on the surface of the weld. It is generally inspected by naked eyes, with the help of standard templates, gauges, and magnifying glasses. If there are defects on the surface of the weld, there may be defects inside the weld.
(2) Density inspection For welded containers that store liquid or gas, the imperfections of the weld seam, such as penetrating cracks, pores, slag inclusions, incomplete penetration, and loose structure, can be found by the tightness test. The tightness test methods include kerosene test, water-carrying test, water wash test, etc.
(3) Strength test of pressure vessel In addition to the tightness test, the pressure vessel must be subjected to a strength test. There are two common types: hydraulic test and pneumatic test. They can test the tightness of welds of vessels and pipes that work under pressure. The air pressure test is more sensitive and rapid than the water pressure test. At the same time, the product after the test does not need to be drained, which is especially suitable for products with difficult drainage. But the risk of the test is greater than that of the hydraulic test. When conducting the test, the corresponding safety technical measures must be followed to prevent accidents during the test.
(4) Inspection by physical methods Physical inspection methods are methods that use some physical phenomena to measure or inspect. The inspection of internal defects of materials or workpieces generally adopts non-destructive testing methods.