DIN_28007-1-Tolerance for General Use_en(6)

不锈钢一般公差

DIN 28007-1 Jul 1986Page 6

Explanatory notesFlatness

During the discussions on this standard the question concerning the necessary flatness of flange sealing faces wasthoroughly examined with the result that despite the great number of influencing variables (temperature, pressure andviscosity of the media to be sealed, flange stability, bolt loads, gasket properties etc.) it is necessary to establish asimple method for the determination of the flatness as well as for the specification of the limit deviations. The workinggroup dealing with this standard therefore proposes to measure the flange faces in circumferential direction using afeeler gauge. The deviation from flatness, defined as the difference in height normal to the flange face, shall at no pointexceed a value of 0,1 % of the shorter distance between two measuring points as measured in circumferential direction(the longer distance shall complement the shorter one to the full circumference). According to this conception, largerlong-wave differences are permissible. Short wave deviations, however, shall remain small. It remains to be seen

whether or not practical use of this method will be successful.

Circumference developed

Depth x

The designations given in the figure can be used to describe the limit deviations from flatness by the followingrelationship:

X1 X2UK

100≤0.1

or, since the magnitude of the measuring distance UK can be arbitrarily chosen and the condition is to be fulfilled at anydistance, also by:

dXdU

≤0,001

The preceding considerations only serve the purpose of explaining the requirements for flatness as specified in thisstandard.

International Patent Classification

B 01 D 3/00 – 3/08B 01 D 3/10 – 3/42

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