The takeover hole has been enlarged – is this handling appropriate? Will the stress be greater?
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This post was last edited by youlong1008 on 2016-3-18 at 21:04. We have a high-pressure vessel with a wall thickness of over 200 mm. When making holes in the vessel’s shell, we accidentally enlarged the size of the connection holes; the drawings specified DN500, but they were mistakenly made to DN800. The connection parts are fitted together within the vessel shell. We want to purchase larger connection forgings with larger root dimensions, while keeping the inner diameter at DN500 to ensure that the requirements are met. However, since the hole sizes have increased, will this result in higher welding stresses? Is it necessary to recalculate the stress check? Is it appropriate to handle it this way? Are there any other factors that need to be considered?
It is recommended to consult the designer; design calculations are required
It is necessary to carry out stress analysis calculations again
Why must it be calculated? The original design called for an embedded joint, and it remains a joint today; the thickness hasn’t changed at all, as everything has been fully welded together.
I wonder what the diameter of your containers is? If the diameter is small and the opening exceeds the limits, the problems will be even greater. After the holes are made, the strength of the container itself is reduced, and factors such as welding stress and various types of loads make the situation quite complex. It’s not the case that, as you might think, \"the thickness remains unchanged and full penetration has been achieved\" is sufficient to explain everything. So I still recommend that you recalculate.
The strength of forgings is lower than that of sheets, especially with such thick walls. This still needs to be discussed with the designer.
The size of the opening also determines the strength of the container itself. It’s not the case that just because welding is complete and the inner diameter of the pipe remains unchanged, there will be no impact; in such cases, a new strength assessment is necessary
It becomes problematic when the take over opening exceeds half of the container’s diameter
The diameter of the access opening we have doesn’t even reach half of the cylinder’s diameter; it’s less than 1/3 of it.