Want to drill threads on a tube
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This post was last edited by Missergux on 2017-12-28 at 15:11. If I want to drill an M20 thread into a pipe, what should be the DN of that pipe? What is the wall thickness? What is the thread length?
This question is too difficult; think carefully about it.
The purpose isn’t specified; it would be better if there’s a sketch.
Use a threaded pipe sleeve and weld it to the pipeline.
Using threads to determine the pipe diameter is backwards; first determine the pipe size
When DN is greater than 20, the wall thickness depends on the DN of the pipe being used – whether it is a thick-walled pipe – and the thread length is equal to the wall thickness.
It seems the original poster didn’t clarify the issue: Are screw holes to be drilled at one end of the tube, or radially within the tube?
Based on your description, it seems you want to drill an M20 internal thread in the inner hole at one end of the tube, so that it can be screwed onto an M20 bolt. Generally speaking, for the M20 thread, the standard refers to the coarse-threaded M20*2.5 type, with a major diameter of 20 mm and a minor diameter of 17.294 mm. Therefore, the inner diameter of the tube should be 17 mm; if it is less than 17 mm, it must be enlarged to 17 mm. If the inner diameter is greater than 17 mm, a standard M20 internal thread cannot be formed. The outer diameter of the pipe should be 2 mm larger than 20 mm on one side; therefore, an outer diameter of 24 mm is appropriate. It can also be larger, but it must not be less than 24 mm. To determine the specific nominal diameter suitable for use, please refer to a table or consult the supplier. The thread length should be between 10 mm and 30 mm, depending on the external thread you need to connect.
The poster’s plan is basically unworkable; why not consider using pipe fittings?