Corrosion Damage Behavior of X65/Incoloy 825 Welded Bimetallic Composite Pipe in H2S Environment

Bingying Wang,Yige Liu,Gan Cui,Tongle Zhang

doi:10.3389/fmats.2021.709101

Bingying Wang, Yige Liu + Show 2 more

Open Access

https://doi.org/10.3389/fmats.2021.709101

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Abstract

For the long-term service of X65/Incoloy 825 bimetallic composite pipe girth welds in the H2S environment, the corrosion damage behavior was investigated. Characterizations of welded joints were conducted by OM, SEM, XRD, and EDS. The pitting corrosion’s 3D surface morphology of welded joints in NACE-B solution saturated with H2S was investigated. The results show that composition segregation occurs in the welding process, and the Laves phase appears between dendrites, which lead to the decrease in corrosion resistance. The maximum depth of the corrosion pit is 2.46 μm after 30 days, 4.54 μm after 60 days, and 10.94 μm after 180 days. The cell automata (CA) model of corrosion damage was established based on the MATLAB program, and the basic elements of the cell automata model were determined. Through the simulation of the electrochemical reaction and diffusion process, the influence of different parameters of the pitting corrosion morphology was determined. The simulation results were compared with experimental data, which are available for the prediction of the morphology and size of the corrosion pits on the sample surface after 300 days. The results will be beneficial for the long-term service of the bimetallic composite pipe.

Highlights

With the increasingly severe service environment of oil and gas transmission pipelines, the content of H2S, CO2, and Cl− strong corrosive medium becomes high, which leads to serious pipeline corrosion problems (Bunaziv et al, 2019)
It can be seen that the microstructure of the weld specimen is composed of fine primary dendrites of the austenitic γ phase and the interdendritic eutectic phase
The results show that the contents of Cr and Ni are lower in the corrosion pit area due to the segregation, while the contents of Mo and Nb between dendrites are less, so the interdendritic area is easy to be corroded

Summary

INTRODUCTION

With the increasingly severe service environment of oil and gas transmission pipelines, the content of H2S, CO2, and Cl− strong corrosive medium becomes high, which leads to serious pipeline corrosion problems (Bunaziv et al, 2019).

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT