China Steel Structure Residential Building Steel Structure Villa

The quality of Steel Frame Buildings welding directly affects the safety of the overall project, so non-destructive testing of welds is a very important link. Weld testing includes the following:

Non-destructive testing of internal defects in welds
(1) Penetrant inspection Penetrant inspection is a non-destructive inspection method that uses the penetrating effect of a fluorescent dye or a red dye to display traces of defects. Commonly used methods include fluorescence inspection and color inspection.
Spray a red colorant with good penetrability on the surface of the cleaned weldment. After it penetrates into the defects on the weld surface, wipe the surface of the weldment clean. Then apply a layer of white display liquid. After drying, the colorant that has penetrated into the defects of the weldment is adsorbed by the white display agent due to capillary action, showing red traces of defects on the surface. Penetrant testing can be used on any material with a smooth surface.
(2) Magnetic particle inspection Magnetic particle inspection is to magnetize the weldment in a strong magnetic field, so that the magnetic field lines pass through the weld. When encountering defects on or near the surface of the weld, magnetic flux leakage is generated and attracts the magnetic iron oxide scattered on the surface of the weld. pink.
The location and size of the defect can be judged based on the traces of adsorption of iron powder. Magnetic particle inspection is only suitable for detecting defects on the surface or near the surface of ferromagnetic materials.
(3) Radiographic inspection There are two types of radiographic inspection: X-ray and Y-ray inspection. When rays pass through the inspected weld, if there is a defect, the attenuation of the ray passing through the defect is small, so the film on the back of the weld is more sensitive to light. After the film is developed, black spots will be displayed on the defective area. Or stripes.
X-ray irradiation time is short and fast, but the equipment is complex and expensive, and its penetration ability is smaller than that of Y-rays. The thickness of the weldment to be detected should be less than 30mm. Y-ray inspection equipment is lightweight, easy to operate, has strong penetrating ability, and can illuminate 300mm steel plates. No power supply is required during transillumination, making it convenient for field operations. But when detecting less than 50mm, the sensitivity is not high.
(4) Ultrasonic testing Ultrasonic testing uses the principle that ultrasonic waves can propagate inside the metal and will be reflected and refracted when encountering the interface between two media to detect internal defects in the weld.