After the weld on a steel plate is polished flat, what methods can be used to locate that weld?

There are several ways to locate welds: 1. Use magnetic particle testing: Apply a layer of iron powder or magnetic particles to the steel plate, then use a magnetic device to attract these particles to the weld area, allowing the location of the weld to be clearly seen. 2. Use of ultrasonic testing: By transmitting ultrasonic waves across the surface of the steel plate, it is possible to determine the location of the welds. Ultrasonic testing equipment can detect the depth and position of these welds, thereby identifying their location. 3. Have professionals conduct inspections: If the above two methods fail to detect the weld, it is possible to engage professional inspection agencies, such as weld inspection companies or engineering consultants, to carry out the inspection. They will use more precise instruments to locate the welds. .

If the surface defects are not very apparent, you can try the following methods: 1. Use a magnifying glass or microscope to examine the surface of the steel plate one by one, looking for signs such as tiny cracks or bubbles caused by welding. 2. Use an infrared thermal imager, which can detect the temperature differences at the welding area and its surroundings, thereby identifying the location of the weld. 3. X-rays or gamma rays can be used for detection; this method requires trained professionals to operate it and involves the use of high levels of radiation, so it is not suitable for use in ordinary industrial settings. 4. Laser scanning technology is used, which enables three-dimensional scanning of the steel plate surface to determine the geometry and location of welds. Regardless of the method used, safety must be ensured, and relevant regulations and procedures must be followed. .

The area where the weld might be can be cleaned to reveal a metallic shine; after applying a mild acid for about ten minutes, it can be rinsed off with water. Once dried, the weld will become visible； If the hardness of the weld is higher than that of the base material, it can be detected using a hardness testing method.

If it’s on a device or fitting, is it really necessary to make it so complicated? Just check the welding records from the maintenance or major repair work. If such records do not exist, it means that the company has not achieved the quality management system standards of the ISO 9000 series; in that case, there is no need to inspect any welds.

What are the visual differences between the weld and the base metal after brushing with a weak acid?

The suspected weld is located on the equipment’s head; it is believed that the manufacturer made a mistake in drilling the holes and then tried to repair it by welding. Now, no records of this weld can be found. The diameter of the head is 3400 mm. The equipment cannot be emptied at the moment, so RT testing is not possible. If the weld cannot be located, how can UT testing be used to determine whether the defect is in the base material?

I suggest you change the title to make it more intuitive. :Lol, it seems there are miswelded holes on the cover; after grinding them smooth, how can those holes be found again?