How to ensure the flatness and perpendicularity of flanges

Flatness is generally achieved by controlling the flatness of the cylinder’s end face, while perpendicularity is ensured by controlling the perpendicularity between the cylinder’s end face and its wall. Place the cylinder on a steel platform (with a flatness of no more than 1 mm), adjust the verticality of the cylinder wall relative to the steel platform to meet the requirements, use a scribing tool to draw lines on the cylinder at the appropriate height, and then trim the cylinder to those marked positions – this will ensure the flatness of the cylinder as well as the verticality of its end face with respect to its wall ； By machining the groove and placing the flange on a platform to connect it with the cylinder, the flatness and perpendicularity of the flange can be ensured. During welding, care must be taken to control the flange’s flanging.

1. When installing the flanges on the vertical cylinder, first ensure that the flatness of the cylinder’s end face meets the required standards; level the end face of the cylinder to guarantee its vertical position. Draw a reference circle outside the drilling lines (with the center of the hole as the center and a diameter larger than that of the flange), and measure the distance between the outer edge of the flange and the reference circle on the upper, lower, and horizontal lines – these distances should be consistent across all locations； Then, the perpendicularity of the flange surface is verified using a plumb line to ensure it meets the requirements. 2. When installing the connection flanges on a horizontal cylinder, the same reference circle method is used; however, to determine whether the flange surface is parallel to the vertical direction of the cylinder wall, reference objects in the surrounding area are generally used for visual verification. 3. The flatness of the flange surface itself is ensured during machining. This post was last edited by newn on 2009-4-25 17:58.]

I believe that welding alone cannot achieve ideal results; to obtain higher positional tolerances, mechanical processing after welding is necessary to ensure those tolerances

I disagree with what was said above. If mechanical processing is required after welding each flange to ensure the tolerances, it will drive plumbers crazy – where can they find so many workers for this task? The boss loses everything, while the workers get exhausted. A skilled plumber can ensure levelness and perpendicularity with just a level

Special tooling design is required; otherwise it will be very difficult

It depends on what tolerance requirements are specified; as long as the requirements outlined in the drawings are met, it doesn’t matter whether special tooling is used or not.