Is it better to have circumferential welds or longitudinal welds for the cylinder splicing welds?
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This post was last edited by lime1907 on 2016-7-25 22:01. A low-pressure heat exchanger is to be designed, with the fluid on the shell side being a lithium bromide aqueous solution that is somewhat corrosive, similar to table salt. Since the cylinder is quite large and needs to be assembled, we carry out butt welding of the flat sections before rolling them. Is it better to use circumferential welds or longitudinal welds? Additional question: The expanded dimensions of the cylinder are 8*2150*2400 mm, but the steel plates purchased are 8*2000*6000 mm. Our operators first weld the two steel plates together and then roll them into a cylinder. The weld used for joining them is a circumferential weld; therefore, this weld will be subjected to rolling. Will this have any adverse effects on that weld? If the length of the cylinder isn’t too great, would a longitudinal seam be better?
It would be better if the butt welds were in the form of circumferential seams; the fewer longitudinal seams, the better. Due to the large circumferential force, the longitudinal seam is subjected to even greater stress.
The circumferential seam is done. Ring seams are subject to less stress; Class B welds ； The longitudinal seam is subject to high stress; it is a Class A weld.
There is a question: since welding is done first and then rolling, could rolling the cylinder have an adverse effect on the circumferential weld?
There certainly is. To ensure no redundant work, it is recommended that if the equipment’s weld coefficient is 1.0, 100% RT testing at grade II be conducted prior to welding; if the weld coefficient is 0.85, then 100% RT testing at grade III should be carried out before welding. Otherwise, it is still recommended to roll up the cylinder before performing welding.
The longitudinal seam is better, with lower internal stress and easier rolling.
I’m not quite sure what the original poster means, but the usual width of steel plates is within 3 meters, and the same applies to the rolling width of conventional coil rolling machines. For ordinary pressure vessels, this ensures that the width requirements for the vessel sections are met. If the diameter of a single tube section is large and the length of the steel plate is not sufficient, it is possible to splice together longer steel plates and roll them into shape. However, if the diameter is too large, due to limitations such as the height of the cranes in the factory, it is also possible to roll the material in sections first and then weld them together to form the tube section. As for the stress on longitudinal seams and circumferential seams, it is true that longitudinal seams are subject to greater stress. However, during the manufacturing process, there is no need to worry too much about this; it is better to minimize the use of circumferential seams, as this reduces the amount of welding required.
Before rolling the plate, it is usually necessary to splice it because the diameter is too large and the length of the steel plate is insufficient; that is, longitudinal seams are spliced first. There is no such thing as splicing circumferential seams first and then rolling the cylinder – if the circumferential seams are spliced first, will the width of the rolling machine be sufficient? LZ has been at the container factory for not long, right?
Agree with what was said on floor 9. Since the diameter of a single tube section is large and the length of the steel plates is not sufficient, it is possible to splice together longer steel plates and roll them into shape. However, if the diameter is too large, due to limitations such as the height of the cranes in the factory, it is also possible to roll the material in sections first and then weld them together to form the tube section. During the manufacturing process, there is no need to overthink it; it is better to minimize the number of circumferential seams, as this reduces the amount of welding required.