Does the weld spacing of the equipment meet the design requirements?
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The company’s stripping tower is a conical device equipped with a jacket for heating; the lower part of the cone is connected to the lower head via flanges, while the upper flange is connected to the cone through a short section of DN400 with a length of 100 mm. The distance between the two welds is only 100 mm. I wonder whether this design meets the requirements of relevant design specifications
In our company, the distance between two welds is generally required to be no less than 100 mm. This is indeed a bit problematic; we can only ensure that the heat-affected zones do not overlap, so it shouldn’t be too serious of an issue
The key point is that the distance between the two welds is only 100 mm – will this ensure that the heat-affected zones do not overlap?
The short-circuit length can be determined based on the pressure vessel flange, but the distance between the welds also needs to be taken into account
It meets the standard requirements: it should be more than 3 times the thickness of the plate, and at least 100 mm in size; refer to GB150.4 for details
The minimum length of the tube section, or the minimum distance between two welds, is intended to prevent the overlapping of heat-affected zones. In fact, the heat-affected zone of a weld is proportional to the thickness of that weld. Moreover, the minimum length of the tube section or the minimum distance between welds specified in the standards can be selected as appropriate based on actual conditions. :)
The equipment design shown in the diagram meets the standard requirements.
Note that what the original poster mentioned is the gap between circumferential seams, not the longitudinal seams; this has nothing to do with the standard requirement that 3 times the plate thickness should be at least 100 mm. Just considering the distance between these two seams, there should be no problem. However, the person who posted the question needs to check whether the conical section has straight edges; if not, it is necessary to consider whether reinforcement is required for the connection between the conical section and the cylindrical section. If reinforcement is needed, then there are specific requirements regarding the length of such reinforcement sections.
Thank you for your reply. However, the specification states that the length of any individual tube section must not be less than 300 mm. How should this be understood?