Corrosion Experience with Low Carbon Steel R4 Grade Mooring Chain

2021 ◽  
Author(s):  
Øystein Gabrielsen ◽  
Turid Liengen ◽  
Gisle Rørvik ◽  
Solfrid Molid ◽  
Terje Stavang
Keyword(s):  
Carbon Steel ◽  
Low Carbon Steel ◽  
Microbiologically Influenced Corrosion ◽  
Actual Condition ◽  
General Corrosion ◽  
Mooring System ◽  
Low Carbon ◽  
System Integrity ◽  
Significant Difference ◽  
Mooring Chain

Abstract Equinor owns and operates a fleet of floating installations on the Norwegian Continental Shelf (NCS). As the installations are getting older, the importance of knowing the actual condition of the mooring systems has increased, and continuous mooring system integrity evaluation is important for the safekeeping of the assets. As a part of the mooring system integrity management, seabed chains have been replaced for condition evaluation, as in situ inspection techniques so far has not been able to determine the actual conditions of longer lengths of seabed chain. Thorough onshore inspection and full-scale fatigue and break load tests has been performed on retrieved chains, to map the actual condition and effect to integrity. After retrieving seabed chains from approximately half of the floating installations, Equinor now has collected experience on chain degrading mechanisms and corrosion on different locations, water depths and different chain deliveries. The inspections have revealed several corrosion phenomena, where microbiologically influenced corrosion (MIC) due activity of sulphate reducing bacteria (SRB), is observed to have a significant effect on fatigue capacity. An important finding is also that corrosion mechanisms and severity change along the seabed chains. In the Equinor fleet mooring chain grade R4 has usually been used. In total four different vendors have supplied chains, but the vast majority is supplied by two vendors. One of the mooring chain vendors have supplied low carbon (LC) steel chains for the larger chain diameters (larger than 114mm). A significant difference in corrosion is found between the low carbon steel R4 grade chains and other chains. Differences are found both for general corrosion, light surface corrosion and MIC/SRB corrosion. This paper presents and discusses findings on MIC/SRB for seabed chains, in connection with the type of steel used in the mooring chain, demonstrating limited corrosion on low carbon steel chains. Also, special corrosion phenomena found only on low carbon steel chain is presented. These are found to have no or limited effect to integrity of the chains.

scholarly journals Environmental Behavior of Low Carbon Steel Produced by a Wire Arc Additive Manufacturing Process

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 888 ◽  
Author(s):  
Ron ◽  
Levy ◽  
Dolev ◽  
Leon ◽  
Shirizly ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Additive Manufacturing ◽  
Carbon Steel ◽  
Stress Corrosion ◽  
Environmental Behavior ◽  
Low Carbon Steel ◽  
General Corrosion ◽  
Low Carbon ◽  
Corrosion Performance ◽  
Wire Arc Additive Manufacturing

: Current additive manufacturing (AM) processes are mainly focused on powder bed technologies, such as electron beam melting (EBM) and selective laser melting (SLM). However, the main disadvantages of such techniques are related to the high cost of metal powder, the degree of energy consumption, and the sizes of the components, that are limited by the size of the printing cell. The aim of the present study was to evaluate the environmental behavior of low carbon steel (ER70S-6) produced by a relatively inexpensive AM process using wire feed arc welding. The mechanical properties were examined by tension testing and hardness measurements, while microstructure was assessed by scanning electron microscopy and X-ray diffraction analysis. General corrosion performance was evaluated by salt spray testing, immersion testing, potentiodynamic polarization analysis, and electrochemical impedance spectroscopy. Stress corrosion performance was characterized in terms of slow strain rate testing (SSRT). All corrosion tests were carried out in 3.5% NaCl solution at room temperature. The results indicated that the general corrosion resistance of wire arc additive manufacturing (WAAM) samples were quite similar to those of the counterpart ST-37 steel and the stress corrosion resistance of both alloys was adequate. Altogether, it was clearly evident that the WAAM process did not encounter any deterioration in corrosion performance compared to its conventional wrought alloy counterpart.

Study on Microstructure and Friction of Bimetal 1.5Cr4.8Ni with Cast Iron and Low Carbon Steel

2012 ◽  
Vol 565 ◽  
pp. 650-655
Author(s):  
Qi Zhang ◽  
Zheng Yi Jiang ◽  
Guo Liang Xie ◽  
Dong Bin Wei ◽  
Jing Tao Han
Keyword(s):  
Cast Iron ◽  
Carbon Steel ◽  
Hot Rolling ◽  
Low Carbon Steel ◽  
Interfacial Zone ◽  
Low Carbon ◽  
Significant Difference ◽  
Composite Casting ◽  
The Matrix ◽  
Gleeble 3500

A cast iron/low carbon steel sandwich-structured bimetal fabricated through composite casting, followed by hot rolling and hot compression (40% reduction) in a vacuum, and water quenched using Gleeble 3500 thermomechanical simulator. The microstructure of a predominantly martensitic structure is transferred to a matrix with an amount of austenite. The measured results show that the macro-hardness is significantly lower due to the evolution of matrix. A considerable amount of secondary carbides were precipitated from the matrix. This study also shows that a significant difference in the value of coefficient of friction (COF) at the end when hot rolling (HR) was tested under three sets of sliding wear conditions, while those for hot rolling and heat treatment (HT) tends to be merged. An increased wear resistance of interfacial zone is expectable.

scholarly journals The Effect of Desulfovibrio Desulfuricans To Carbon Steel Grade API 5L X70

2019 ◽  
Vol 3 (1) ◽  
pp. 18-23
Author(s):  
Nur Bazilah Ishak ◽  
Keyword(s):  
Weight Loss ◽  
Carbon Steel ◽  
Corrosion Rate ◽  
Ph Value ◽  
Outer Part ◽  
Low Carbon Steel ◽  
Desulfovibrio Desulfuricans ◽  
Microbiologically Influenced Corrosion ◽  
Metal Loss ◽  
Low Carbon

Microbiologically Influenced Corrosion (MIC) caused by the presence of Sulfate-reducing bacteria (SRB) is a big concern in heavy industries. Pipeline infrastructure may experience severe metal loss due to corrosion induced by the species and can potentially lead to catastrophic failure. By studying SRB growth condition, important parameter can be controlled to prevent or slow down a corrosion process. This study discussed on the effect of pH value to the corrosion growth rate on API 5L X70 low carbon steel subjected to outer part of underground pipeline. In this research, the type of SRB that's been used is Postgate C of Desulfovibrio Desulfuricans. There are 80 numbers of samples prepared with various pH value and temperature, which each of the samples contains two coupon steel immersed in the medium together with SRB for 7, 14, 21 and 28 days. The process in determining weight loss is analyzed and the corrosion rate for each steel sample is identified by weight loss. The result is plotted and analyzed, the particular pH values and temperature affect the growth of SRB in the medium where the existence of SRB could accelerate the corrosion rate towards the steel surface of API X-70. The samples are exposed to SRB in days’ time. This experiment aims to determine the optimum temperature for SRB growth and demonstrate the corrosion rate simulation using One-Factor-at-A-Time method (OFAT) method. The consequences of SRB activity, it is shown that pitting corrosion produced on the surface of steel. In fact, the sulphur element is identified as one of the corrosion products due to SRB activity.

scholarly journals CRACKING CORROSION OF LOW CARBON STEEL IN ENVIRONMENT WITH A HIGH CONCENTRATION OF CO2 AND H2S

2018 ◽  
Vol 55 (5B) ◽  
pp. 210
Author(s):  
Nguyen Thi Le Hien
Keyword(s):  
Carbon Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Low Carbon Steel ◽  
Corrosion Cracking ◽  
Test Method ◽  
General Corrosion ◽  
Low Carbon ◽  
Hydrogen Induced Cracking ◽  
Sulfide Stress

Cracking corrosion of API 5CT Grade L80 Type 1 low carbon steel has been studied in a in brine solutions with H2S 12.3 psia and CO2 9.4 psia. Testing was performed according to the methodology reference from the NACE TM0177, Bent-beam test method in solution B for stress corrosion cracking and sulfide stress corrosion cracking test and NACE TM0284, immersion test method in solution A for Hydrogen induced cracking test.The obtained results showed pitting and general corrosion at both temperatures of 24 oC and 82 oC. In case of stress corrosion cracking (SCC) testing at 82 °C, microscopy of the samples tested for 30 days developed pitting corrosion in the surface and cracking starting in the surface of the samples. The cracks, mostly found in the middle of the samples where the maximum bending occurred. General corrosion was also observed in the samples, with significant decrease in the dimensions of the samples after testing (due to general corrosion). However, in case of sulfide stress corrosion (SSC) and hydrogen induced cracking (HIC) tests at room temperature (24-25 oC), no cracking was observed on the sample. 

Development of trimming technology for hot rolled ultra-low carbon steel

1993 ◽  
Vol 90 (7-8) ◽  
pp. 917-922
Author(s):  
Y. Matsuda ◽  
M. Nishino ◽  
J. Ikeda
Keyword(s):  
Carbon Steel ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Ultra Low Carbon Steel ◽  
Hot Rolled

The Effect of Small Defects on Fatigue Life of a Low Carbon Steel

2019 ◽  
Author(s):  
Natalia Gonçalves Torres ◽  
Vinícius Rodrigues ◽  
Edgar Mamiya
Keyword(s):  
Fatigue Life ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Low Carbon
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