A metal pipe nominal diameter 1200, using flange connection. In the original installation technical requirement, "parallelism: tolerance is 1mm/1000mm". How do you measure parallelism? What does this "1mm/1000mm" mean? How do you explain that?Another: flange roughness and how to measure and explain??
The control problem, method of measurement of parallelism is the datum plane placed on the plate, with a dial indicator to measure the surface within a range of 1200 error value does not exceed 1.2 mm.Flatness, in mechanical drawings, shapes and positional tolerances, is popularly known as flatness, defined as the maximum variation of the measured plane and the ideal plane in the tolerance range. The flatness of the reference plane requires a higher level.If the flatness of the reference plane of the flange is strict, the parallelism can be checked with a vernier caliper.
In a given direction, the degree to which the meter is parallel to the reference surface is within the given tolerance range. 1mm/1000mm represents measurement length of 1000 mm, allowing error of 1 mm.
Parallel degree should be marked that flange mounting flange gap when the maximum and minimum width difference, the difference is not too large, is on the corner of the bolt flange sealing, not partial, or in some places more pressure gasket, gasket in some places may be there virtual pressure, although it does not leak, long time might be have a problem,As for flatness, the surface finish of machined surface should be considered as the flange sealing surface can not be a flat surface, and must be opened with mortise or groove
