Improved Understanding of Test Variables in the NACE Tensile Test

A test lab working for a seamless pipe manufacturer launched a research program to improve the knowledge on NACE TM0177 Method A test variability when proof rings are used. The proof rings manufactured by the test lab fulfill the TM0177 requirements. This paper reviews the loading principles of the proof ring arrangement. Calculated stress values including stress release over the 720 hours test duration and as-measured values are compared in order to improve the knowledge on the loading method and measurement of the actual stress and the stress distribution within the tensile specimen when exposed in the H₂S environment. Additional influencing factors such as specimen diameter decrease throughout the test and possible bending are also addressed.