ASTM D2444 Impact Resistance of Plastic Pipe and Fittings

ASTM D2444 covers the process used to determine the resistance of thermoplastic pipe and fittings to impact by a tup (falling weight) under defined conditions.  The mass of the tup shall be 6, 12, 20 or 30 lbs (2.7, 5.4, 9.1, or 13.6 kg) and shall fall from a maximum height of at least 10 ft (3.0 m) and a minimum of 2 ft (0.6 m). There are three interchangeable inserts for the tup, Type A is a cone with a rounded point, Type B is a cylinder with a relatively flat surface, and Type C has a 0.5" diameter “pin” with a rounded end. Two specimen supports (either a V-block or a Flat Plate) are defined in the standard.  The combination of test variables which offers reasonably repeatable results with the test being easy to run with little or no hazard to personnel is the one that should be used.

The impact resistance of thermoplastic pipe and fittings relates to its suitability for service and to quality of the processing. It may also provide a relative measure of the tested material’s resistance to breakage during handling and installation, and in non-buried applications, to in-service breakage. Results gathered by this test can be used as the basis for establishing impact test requirements in product standards; to measure the effect of changes in materials or processing on the product and to measure any effects of the environment on the pipe or fittings.

Though the test defined in the standard calls for visual inspection after impact to determine if the specimen has failed, by including instrumentation with our Data Acquisition System, Bluehill Impact software and instrumented tup failure points/modes that may remain hidden under normal test conditions can be found. One piece of information that may not be found without the use of instrumentation is the first crack or incipient damage point.  Pipes or fittings may fail in interior areas and remain undetected when visually inspected.