Improvements of existing Chlorine Resistance Method and Discussion of Method’s Suitability for Different Polyolefin Materials

Session 7A
4:10 pm

Jarno Hassinen, Exova Nukoping

With the implementation of NSF Protocol P171 in 1999 and the subsequent adoption of ASTM F 2023 and ASTM F 2263 an extensive number of chlorine resistance investigations have been conducted on polyethylene and cross-linked polyethylene (PE-X) pipes. New applications and the successful development of new materials depend on reliable test methods to evaluate their suitability. This paper presents experimental data generated using the test method described in ASTM F 2023 and the conclusions from a comprehensive study conducted on four different polyolefin materials commonly used for hot and cold water applications according to ISO product standards.

The use of the existing chlorine resistance method may serve as a tool for evaluating the variability of chlorine resistance on materials of the same type as long as no significant scatter or stress dependency of results is observed. However, this paper presents the limitations of the method when too high test temperatures and/or stresses are applied. This may lead to invalid extrapolation for similar materials and may become even more critical upon comparing the oxidative influence of chlorine on pipes produced from different polymer materials.

The paper proposes validation criteria of test results and modifications to the test method to account for the variable and excessive stress and/or temperature dependency of applying standard test conditions, which can result in pessimistic or over-optimistic lifetime extrapolations being made via regression analysis to end use application temperatures of piping systems. New validation criteria and improvements of reporting requirements are discussed and felt as necessary steps for successful development and use of new innovative piping materials.

Jarno Hassinen Project Manager
Mattias Svedberg Operations Manager