Flange tolerance issues for equipment
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These past few days, I’ve encountered a rather tricky company: for the DN1000 Type A equipment flanges, the drawings do not specify tolerances for any other aspects, except that the inner diameter tolerance is set at 0–0.01 mm. I was wondering then whether there’s something wrong with the designer of these drawings. The tolerances for the cylinder made from a 1-meter diameter coil aren’t that tight either; with such tight tolerances on the inner diameter of the flange, will the cylinder fit once it’s processed? I kept communicating with the purchasing department back and forth; they said it had to be manufactured according to the drawings, and I didn’t know what to do.
The equipment flange is machined, with an inner diameter tolerance of 0~0.01 mm achievable.
This post was last edited by sdwfsgyykai on 2019-4-4 08:15. The tolerance can be achieved, but the problem is that type A flanges are welded by inserting the cylinder into the inner diameter of the flange. The tolerances for the cylinders formed by rolling will definitely be large; what will happen if they can’t fit through? Should I enlarge the inner diameter of the flange a bit more?
The standard tolerance is 0-3.0mm. What I can’t understand is why such a small tolerance is needed.
It’s probably a mistake in the drawings; there’s no need for such strict tolerances for type A flat welding flanges:lol
Yeah. I’m also puzzled; with such a small tolerance, it must be very difficult for them to assemble it back together.
This post was last edited by yechao25038 on 2019-4-3 at 16:17. We process the Type A flanges ourselves, and have to wait until the cylinder shell is rolled before proceeding with their fabrication. Maybe their cylinders are made from forged pieces as a single unit, haha :P
Just make the cylinder smaller, won’t that do?
If it is rolled smaller, there is also an issue with ellipticity. The ellipticity of the rolled shape must also exceed 0.5 mm, right?