Evaluation of the SCC-CO2 susceptibility of flexible pipe tensile armor wires

Santos, Fábio Pinheiro; Poloponsky, Ingrid; Modiano, Susana; Ribeiro, Carlos Eduardo Gomes; Motta, E.P.

doi:10.48072/2525-7579.rog.2020.177

Cited by 3 publications

(4 citation statements)

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“…Furthermore, at 100% of the AYS, all material grades were observed to be susceptible to CO 2 -SCC for a CO 2 fugacity greater than or equal to 15 bar. This shows a significant contradiction with the work done by Santos et al 32 where 4pB test results showed no CO 2 -SCC on a material grade tested at 80 bar fCO 2 and with an applied load at 100% of the AYS. It is believed that the reason behind this difference from our results may be linked to differences in the experimental set-up and sample preparation.…”

Section: Impact Of Fcocontrasting

confidence: 96%

“…Based on these results, 40°C was identified as the optimum temperature for the initiation of CO 2 -SCC and utilised as the base temperature in testing the influence of other parameters. This particular observation was also reported in a study carried out by Santos et al 32 thus further consolidating the impact of this parameter.…”

Section: Impact Of Temperaturesupporting

confidence: 85%

“…Furthermore, the article 32 shows no indications of SCC on a high strength sweet service wire tested at conditions of 10 bar and 40°C after a period of 180 days. In our work, CO 2 -SCC cracks were observed in sweet service, high strength wires (Steel A) in tests carried out with as low as 3 bar fCO 2 as shown in Figure 18 (a).…”

Section: Impact Of Fcomentioning

confidence: 93%

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CO2-SCC in Flexible Pipe Carbon Steel Armor Wires

Motte

Joshi

Chehuan³

et al. 2022

Corrosion

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Carbon Dioxide-induced Stress Corrosion Cracking (CO2-SCC) is an environmentally assisted corrosion cracking phenomenon that has recently been identified as a new failure mode in flexible pipe armor wires. The phenomenon has been observed to take place notably in severe CO2 environments and is a cause of great concern to the flexible pipe industry. Since its detection, a diverse and extensive testing program has been established to develop an understanding of the phenomenon and define safe application limits for carbon steel wires to prevent the initiation of CO2-SCC. Several different testing methodologies have been explored and small-scale laboratory testing has played an instrumental role to this overall effort. This paper focuses on the results from three different small scale testing methodologies and the impact of different parameters such as CO2 fugacity, temperature and confinement that play a crucial role in the initiation of CO2-SCC. Furthermore, careful prominence has been given to the test set-up and methodology that has been rigorously developed over the last few years. With this developed protocol in place, CO2-SCC has been effectively reproduced on all wire grades in a small-scale testing environment. Results have also shown that for a CO2 fugacity greater than 15 bar and applied stress at 100% of the actual yield strength (AYS), all existing wire grades are susceptible to CO2-SCC thus creating significant limitations to flexible pipe design with respect to this new failure phenomenon.

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Section: Impact Of Fcocontrasting

confidence: 96%

Section: Impact Of Temperaturesupporting

confidence: 85%

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CO2-SCC in Flexible Pipe Carbon Steel Armor Wires

Motte

Joshi

Chehuan³

et al. 2022

Corrosion

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“…Nevertheless, studies investigating the corrosion behavior of armor wires in simulated annulus environments usually consist of exposing the entire surface area of the test specimens to the test environment, without considering the influence of the antiwear layer covering the steel on the corrosion morphology. [ 2–13 ]…”

Section: Introductionmentioning

confidence: 99%

Corrosion of tensile wires covered with PA11 layers in simulated annulus environments at low CO₂ pressure

Silva

Senatore

Gomes

2022

Materials & Corrosion

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High-strength carbon steel wires covered with polymer layers were exposed to different test environments simulating the conditions in the annulus of flexible pipes at low CO 2 pressure and flooded with seawater. The polymer layers mimicked the antiwear tapes which are placed in between the steel layers of the tensile armor of the pipes. Specimens without the polymer layer were exposed to the same test environments for comparison and allowed identifying how the presence of the polymer layer influenced the corrosion mechanism. In some of the experiments, oxygen was introduced into the gas mixture to simulate fresh seawater entering the annulus after a breach in the outer sheath. Surface analysis of the corroded specimens after removal of corrosion scales was carried out by scanning electron microscopy, optical profilometry, and confocal microscopy. The polymer layers were observed to have a considerable effect on the corrosion morphology.

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Flexible Pipes Subjected to SCC CO2: Review and Means to Increase Reliability on Service Life Applied to Brazilian Pre-Salt Fields

Brandao

Pires

Poloponsky

et al. 2021

Day 4 Thu, August 19, 2021

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Flexible Pipes were widely used in Brazil offshore developments and the challenge on overcoming increasing water depths, high pressures and fluids with high contaminants was always present. In 2017 a new failure mode, called SCC CO2 was disclosed bringing such disruption in the use of this equipment since, at that time, the conditions observed in Brazilian Pre salt were like the "perfect storm" for the failure mode to happen. It had high concentrations of CO2, therefore high permeation in the anulus, high stresses and the possibility to have anulus flooded as result of an outer sheath breach or even due to permeated water. These were the triple conditions needed to have the failure, considering that all metallic material used in the pipe were subjected to this phenomenon. Since the discovery was made, several test campaigns to better understand and replicate the phenomena started. They covered pipe retrieved from field dissection, several small-scale materials testing, and fracture mechanics to create reliable crack propagation calculations. There were 3 mains focus areas; to understand how to deal with the installed fleet, to define the conditions in which a crack would appear and define, using fracture mechanics, how long a crack would take to break the wire. In other words, it was intended to define what is the remaining service life. As a result of this investigation some initial beliefs like that all materials were subjected to the phenomena and that a solution was far away were somehow reduced and reshaped. There was also the initiative to embark on technology for detection of the anulus condition, mainly to define if it is flooded or not. Some ROV inspection means were added to the endfitting and some sensors were added to the interconnected pipe sections that allow conditioning monitoring or inspection from the floating unit, not using a ROV. This paper will cover the improvements done since the disclosure of the phenomena in 2017, reviewing what is known about it so far, what is still to be discovered and how the results achieved to date can contribute for a more reliable and longer service life for the flexible pipes to be applied in a rich CO2 environment.

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Evaluation of the SCC-CO2 susceptibility of flexible pipe tensile armor wires

Cited by 3 publications

References 0 publications

CO2-SCC in Flexible Pipe Carbon Steel Armor Wires

CO2-SCC in Flexible Pipe Carbon Steel Armor Wires

Corrosion of tensile wires covered with PA11 layers in simulated annulus environments at low CO₂ pressure

Flexible Pipes Subjected to SCC CO2: Review and Means to Increase Reliability on Service Life Applied to Brazilian Pre-Salt Fields

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Evaluation of the SCC-CO2 susceptibility of flexible pipe tensile armor wires

Cited by 3 publications

References 0 publications

CO2-SCC in Flexible Pipe Carbon Steel Armor Wires

CO2-SCC in Flexible Pipe Carbon Steel Armor Wires

Corrosion of tensile wires covered with PA11 layers in simulated annulus environments at low CO2 pressure

Flexible Pipes Subjected to SCC CO2: Review and Means to Increase Reliability on Service Life Applied to Brazilian Pre-Salt Fields

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Product

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Corrosion of tensile wires covered with PA11 layers in simulated annulus environments at low CO₂ pressure