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.
This paper reviews the loading principles of the proof-ring arrangements. 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 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 effects are also addressed.
Keywords: NACE TM0177 Method A, constant load, proof-ring, stress, stress release,
specimen bending