ABSTRACTPlastic pipes reinforced by cross helically wound steel wire (PSPs) have been widely used in the transportation of petroleum, natural gas, municipal water, and so on. With the applications of PSPs in high‐temperature and high‐pressure environments, the problem of PSP joints has begun to appear. The bulging failure of PSP joints is the main failure mode, and steel–polymer interfacial debonding is the major factor causing bulging failure. Thus, it is crucial to understand the failure criterion of steel–polymer interfacial debonding. In this study, pull‐out tests were carried out at different temperatures and loading rates. A finite element (FE) model was developed on the basis of the cohesive element. We proposed that the key parameter for the bugling failure of PSPs was the shear stress of the steel–polymer interface. We assumed that when the shear stress exceeded the shear strength, this led to the degradation of the interface. By iteratively presetting the shear strength and calculation of the FE model, the FE results were verified with experimental results. We found that the shear stress of the front part of the FE model first reached its peak value; its interface began to degrade, and then, the shear stress decreased. The peak value of the shear stress moved toward the end part of the FE model, and the shear strength could be obtained. Finally, the effects of the temperature and failure time on the shear strength were investigated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45064.