Tank welding issues
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Today, when I was on site, I saw the workers fixing the steel plates before starting to weld them; I’m not sure if this complies with the standards； Everyone says that it’s necessary to prepare grooves first and so on; what are the specific steps? I hope someone experienced can provide a detailed explanation
It’s necessary to consider the thickness of the steel plate, as well as the ambient temperature and the material type. 1. If the thickness is generally below 8 mm, welding can be carried out by simply polishing the welding surfaces. 2. If the thickness exceeds 8 mm, it is necessary to make a cut before welding. 3. When the ambient temperature is below zero, it is generally necessary to preheat the weld area; the steel plates on either side of the weld area should be preheated over a distance of 100 to 200 mm. 4. Special materials also usually require preheating, such as 16MnR
For steel plates with special requirements, it is necessary to make cuts, weld after that, perform root cleaning, and then continue welding
2# Wang Zunyi is right. But to correct that, for 16MnR steel plates, preheating is not required if the thickness is less than around 30 mm (I can’t remember the exact figure); preheating is necessary only when the thickness exceeds this value.
Yes, generally a gap of over 8 mm is needed in order to make a cut; otherwise, it’s difficult to achieve thorough welding
For tanks of what size and plates of what thickness, beveling is generally required. Are there any requirements regarding flaw detection?
It depends on which part it is; generally, grooves are not required for the fillet welds at the corners of the frame.
It is necessary to check what the coefficient required for welds is according to the drawings, as well as what the plate thickness is.
1. Check the drawings to determine what type of groove is required for the plate in this area； 2. In the case of submerged arc automatic welding, preheating is generally not required ； In the case of manual welding, the preheating temperature is determined based on the material; for most carbon steel plates, it is around 150 degrees Celsius ； 3. Preheating is required when welding carbon steel plates with varying thicknesses, in order to eliminate stress concentration ； 4. If the equipment requires overall heat treatment, no welding shall be performed after the heat treatment.