Cyclic loading and marine environment effects on the properties of HDPE umbilical cables

This work presents a study of the effects of cyclic loading and marine environment on the mechanical properties of high-density polyethylene (HDPE) used in the external layer of submarine cables. Two different types of samples were tested. The first type was tested in the as-received condition whereas the second one was taken from the cyclic-loaded material. The cyclic-load test was carried out in a device, according to the API 17E standard (API 17E-98, Specification for sub sea production control umbilicas). These samples were submitted to a process of artificial aging. All the specimens were submitted to tensile test and the analysis and comparison of the results showed that HDPE suffered alterations in its mechanical behavior, especially the material submitted to cyclic loading. Both aged and as-received samples were observed by using scanning electron microscopy and their hardness was also measured. The results showed that the cyclic loading, the seawater and the ultraviolet radiations accelerated the degradation process of HDPE.