This article is devoted to the study of means and methods for non-destructive testing mechanical properties of polyethylene gas pipelines that have been in operation for 25–55 years. In order to assess mechanical properties, stress at yield was chosen as a key parameter. Stress at yield is determined from the results of tensile tests and is associated with the limiting circumferential (hoop) stress, determined from the results of tests for short-term pressure. Tensile tests require sample cutting and the shutdown of pipelines’ service. To solve this problem of nondestructive testing of pipelines, tests were carried out using the methods of Shore, Leeb and dynamic instrumental indentation. According to the test results, it was revealed that the correlation coefficient between the values of stress at yield and hardness, obtained by the method of dynamic instrumental indentation, is 0.98 which confirms the possibility of the evaluation of the mechanical properties of pipelines by the method of dynamic instrumental indentation.
The article presents an analysis of the most common hardness measurement methods, implemented by portable hardness testers: rebound or Leeb method, static Portable Rockwell (PR) method and Ultrasonic Contact Impedance (UCI) method. These methods are reviewed in terms of the physical nature of the measurements and the influence of the measured sample properties and the probe parameters on the measurement result. The review contains advantages of each method, possible applications, as well as limitations due to the operation principles of probes. The article also contains the analysis of solving the problem of measurement results validity and their conformity with standardized hardness scales.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.