This appendix describes a method of automating the selection of a detail sketch based on component rotation, such as an olet with respect to the header pipe, to show fabrication information from a library of possible sketches. There are several aspects to this problem:
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The convention used to calculate the angle, which must be consistently applied under all piping configurations
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The convention used to represent the angle on the detail sketch, which must be consistent with the calculation method with respect to the axis from which rotation is measured and the direction of rotation
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The pipework orientations to which the automated sketch selection should apply, that is, pipework can be vertical, horizontal, sloped and non-orthogonal or skewed.