Wall thickness issues of stainless steel seamless pipes above DN350
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There are no specified wall thickness requirements for Sch40S and Sch80S pipes of DN350 and above. I need to use pipes with a DN500 diameter; if forged pipes are used, the calculated wall thickness is 19 mm, resulting in an inner diameter of 470 mm. Is this acceptable? If it is still necessary to increase the outer diameter of the take over, what should be an appropriate value for its inner diameter?
No way, friend. 19 is definitely too thick; since you’re using imperial pipes, it should be connected to the valve flange as well. The outer diameter is difficult to change; the inner diameter can be determined based on the wall thickness of the next higher grade.
Thickening of the pipe wall is a common phenomenon, but as mentioned in point #2, it’s important to ensure proper coordination and to avoid deviations from the specified limits. If calculations require thickening, and in cases like yours where the increase is significant, both the inner diameter and the outer diameter need to be taken into account
There’s no issue with the inner diameter of the pipe flange for equipment connection; it depends on any special requirements of the actual external piping. This diameter can also be achieved by rolling steel plates; it’s not necessary to use forgings.
I don’t quite understand what you mean. If it’s a device, it will be manufactured according to your design; for the connection flanges, standard components are usually used. I don’t understand why you’re considering the inner diameter? If the inner diameter is too small, choose a larger model, such as 550. If the calculated flow rate requires it, or if equipment components need to be installed through this area and the dimensions are insufficient, opt for a larger size.
The common practice is to ensure that the ratio of the inner diameter to the outer diameter is larger than the standard value; thinning can be used when connecting with flanges. The thickness of your gasket is likely intended for reinforcement through openings, and the dimensions at the end that connects to the flange can be selected according to standards.
Pay attention to the requirements for integration. I determine the inner diameter using the table below, and then increase the outer diameter as required by the calculations.
Wall thickness series of 40S and 80S are actually available for DN350 and above; your standard is too outdated. For DN350~DN500, 40S is 9.53 and 80S is 12.7.
This pipe diameter is generally fabricated by rolling steel plates; forgings can also be used. The thickness is determined based on the reinforcement calculations required. If it is too thick, the inner diameter of the external connection pipe should be taken into consideration and made consistent, with the outer diameter increased appropriately. This does not affect the inflow or outflow of the medium.