In order to establish a proper method for testing the hardness of plastic pipes, various kinds of experiments were perfomed on plastic pipes being used most commonly. From the results, it was possible to establish the most proper method.
The main results obtained are as follows:
(1) Pipes should be tested after 72 hours or more since they were molded.
(2) In the case that the measurements are to be made at 5 spots on a pipe, the length of the samples should be more than 70mm for types A, C, D and H, and more than 20mm (except when pipes of the standard length are used) for type I. The thickness of the samples should be at least 4.0mm for PVC, 3.0mm for MA, 4.0mm for P. P, and 3.5mm for ABS.
(3) The degree of final roughness of the surface of the samples should be 3.2S, which can be achieved by using Emery Sandpaper #800∼#600.
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