Skip to main content
White Papers

Failure of Polyethylene Supply Line Tubing

Over the course of the last few years, I have performed a number of failure investigations on nominal ¼ in. outer diameter polyethylene supply line tubing. I have observed a variety of different failure mechanisms, including oxidation, creep rupture, mechanical overload, mechanical impingement, and chemical attack. The images in this post represent two contrasting responses of the polyethylene tubing, one demonstrating a relatively high level of ductility, and the other exhibiting brittle failure.

The ductile failure example exhibits a single longitudinal crack, corresponding to hoop stresses from internal pressurization. The failure features indicated that at some point during operation, the internal pressure was higher than the material strength, which led to failure. This produced the observed macro deformation, including significant stretching, yielding, and deformation.

The brittle failure example was also present as a single longitudinal crack, again, corresponding to hoop stresses from internal. The failure occurred via brittle fracture of the tubing through slow crack growth associated with a creep rupture mechanism. Essentially, the applied stress exceeded the long-term strength of the material.

In both cases of the polyethylene supply line failure, the cracking initiated along the inner diameter wall of the tubing and extended outward. This would be expected to be the area of highest stress, corresponding to internal pressurization. Neither of the tubes showed obvious signs of mechanical damage, abuse, or material degradation or alternation. As such, the failures were associated with the applied internal stress, and the ability of the material to withstand the applied stress over the time of application.

Polyethylene supply line tubing - ductile crackingPolyethylene supply line tubing - brittle cracking


For more information on tubing and hose failures, check out this article: The Evaluation of Appliance Hose and Tubing Failures


Jeffrey A. Jansen

Jeffrey A. Jansen is the Engineering Manager and a Partner at The Madison Group. He was elected as a Fellow of the Society by the Society of Plastics Engineers. Jeff is a proven plastic professional with more than 30 years of experience solving problems and addressing opportunities related to polymeric materials. He specializes in failure analysis, material identification and selection, as well as compatibility, aging, and lifetime prediction studies for thermoplastic materials. Jeff has performed over 5,000 investigations, both for industrial clients and as a part of litigation. He regularly presents seminars and webinars, covering a wide range of topics related to plastics failure, material performance, testing, and polymer technology. Jeff is a graduate of Carroll College and the Milwaukee School of Engineering.