High-Pressure SSC Testing of TMCP Large-Diameter Pipeline Steel

In the recent years concerns have been raised on the validity of 1 bar H2S testing to be representative of the full extension of SSC region 3 as currently defined in NACE MR0175 / ISO 15156-2. Within this work SSC four-point bend tests have been performed on base material and weld specimens from TMCP-based large-diameter pipes at exposure conditions in the range of 1-12 bar H2S partial pressure in the presence of different levels of CO2 up to 24 bar. The results are discussed based on microstructure and hardness of the tested pipes. Metallographic evaluation of the specimens to distinguish between SSC, grooves or stress-induced pits has been performed based on a recently published micrographic evaluation criteria chart. For this evaluation method, several examples are presented and discussed to contribute to the collection of data as a basis for damage feature evaluation. The results show that the tested TMCP-based large-diameter pipes are resistant to SSC at partial pressures of H2S above 1 bar, based on material parameters and test conditions. It is recommended to further investigate how the limits of SSC resistance depend on the quantity of CO2 present.
Product Number: 51324-20855-SG
Author: Thomas Haase; René Rüter ; Christoph Bosch
Publication Date: 2024
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