Strain Hardening Modulus (SHM) and Natural Draw Ratio (NDR) have both been widely discussed for their capabilities to provide insights into the slow-crack growth (SCG) performance of polyethylene (PE) materials. At this point, no broad industry initiatives have arisen to formalize an ASTM International procedure for measuring either SHM or NDR. Neither has there been any plastic pipe industry initiatives to introduce either measure into either codes or standards as a replacement or equivalent to existing SCG test methods for PE. Because of the potential benefits to industry from the significant reduction in cost associated with either SHM or NDR in comparison to traditional SCG test methods, it is unfortunate. This paper will present the literature establishing the capabilities of SHM or NDR to replace traditional SCG test methods, consider the reasons industry has not yet adopted these alternative test methods, and propose a path to realization of the potential value of SHM and NDR for PE pressure piping applications.
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