Stainless steel welding process inspection methods

Stainless steel welding inspection content includes from the drawing design to stainless steel products out of the entire production process of materials, tools, equipment, processes and finished product quality inspection, divided into three stages: pre-weld inspection, welding process inspection, post-weld inspection of the finished product. Inspection methods can be divided into destructive testing and non-destructive flaw detection according to whether the damage caused by the product can be divided into two categories.

1. Stainless steel pre-weld inspection

Pre-welding inspection includes the inspection of raw materials (such as base material, welding rods, flux, etc.) and the inspection of welding structure design.

2.Stainless steel welding process inspection

Including welding process specification inspection, weld size inspection, fixture conditions and structural assembly quality inspection.

3. Stainless steel welded finished product inspection

There are many methods of post-weld finished product inspection, commonly used are the following:

(1)Appearance inspection

Appearance inspection of welded joints is a simple and widely used inspection methods, is an important part of the finished product inspection, mainly to find the defects on the surface of the weld and the size of the deviation. Generally through visual observation, with the help of standard samples, gauges and magnifying glasses and other tools for inspection. If there are defects on the surface of the weld, there is a possibility of defects inside the weld.

(2)Tightness test

Storage of liquids or gases in the welded container, the weld is not dense defects, such as penetrating cracks, pores, slag, not welded through and loose tissue, etc., can be used to find the tightness test. Tightness test methods are: paraffin test, water test, water flushing test.

(3)Strength test of pressure vessel

Pressure vessel, in addition to the sealing test, but also for strength test. Commonly, there are two kinds of water pressure test and air pressure test. They can test in the pressure of the work of the container and pipeline weld tightness. The pneumatic test is more sensitive and rapid than the hydraulic test, while the product after the test does not need to be drained, especially for products with drainage difficulties. However, the danger of the test is greater than that of the hydraulic test. When carrying out the test, must comply with the appropriate safety measures to prevent accidents during the test.

(4)Physical methods of testing

Physical inspection method is to use some physical phenomena for measurement or inspection methods. Material or workpiece internal defects inspection, generally using non-destructive flaw detection methods. The current non-destructive flaw detection ultrasonic flaw detection, ray flaw detection, penetration detection, magnetic flaw detection.

① Ray Detection

Ray flaw detection is the use of radiation can penetrate the material and in the material has the characteristic of attenuation to find defects in a flaw detection method. According to the different rays used in flaw detection, can be divided into X-ray flaw detection, γ-ray flaw detection, high-energy ray flaw detection. Because of its method of displaying defects are different, each ray detection are divided into ionisation method, fluorescent screen observation method, photographic method and industrial television method. Ray inspection is mainly used to test the weld internal cracks, unwelded, porosity, slag and other defects.

② Ultrasonic flaw detection

Ultrasound in the metal and other uniform media propagation, due to the interface in different media will produce reflections, so it can be used for internal defects inspection. Ultrasonic inspection of any weldment material, any part of the defects, and can be more sensitive to find the location of defects, but the nature of the defects, shape and size is more difficult to determine. So ultrasonic flaw detection is often used in conjunction with ray inspection.

③Magnetic inspection

Magnetic inspection is the use of magnetic field magnetism of ferromagnetic metal parts produced by the magnetic leakage to find defects. According to the different methods of measuring magnetic leakage, can be divided into magnetic powder method, magnetic induction method and magnetic recording method, in which the magnetic powder method is most widely used.

Magnetic flaw detection can only find defects on the surface and near surface of magnetic metal, and can only do quantitative analysis of the defects, and the nature and depth of the defects can only be estimated based on experience.

④Penetration test

Penetration test is to use the permeability of certain liquids and other physical properties to find and display defects, including colouring test and fluorescence flaw detection two, can be used to check the ferromagnetic and non-ferromagnetic material surface defects.

The above is the stainless steel products processing stainless steel welding inspection content including from the drawing design to stainless steel products out of the entire production process of stainless steel welding inspection methods and directions.

Post time: Aug-25-2023