Corrosion Fatigue of Welded C-Mn Steel Risers for Deepwater Applications: A State of the Art Review

Maddox, S. J.; Pargeter, Richard J.; Woollin, P.

doi:10.1115/omae2005-67499

Cited by 10 publications

(5 citation statements)

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“…Hydrogen sulfide, H 2 S, increases the absorption of hydrogen in carbon steels, 1 causing embrittlement and decreasing the mechanical properties during static [2][3][4] and dynamic loading. [5][6][7][8] Therefore, tests conducted to evaluate materials for sour service usually require the use of this gas. H 2 S is extremely toxic with an Occupational Safety and Health Administration (OSHA) permissible exposure level (PEL) ceiling limit of 20 ppm, 9 and also corrosive and flammable.…”

mentioning

confidence: 99%

Reaction Paths of Thiosulfate during Corrosion of Carbon Steel in Acidified Brines

Kappes

Frankel

Sridhar³

et al. 2012

J. Electrochem. Soc.

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Corrosion tests with gaseous H 2 S require special facilities with safety features, because H 2 S is a toxic and flammable gas. The possibility of replacing H 2 S with thiosulfate (S 2 O 3 2− ), a non-toxic anion, for studying stress corrosion cracking of stainless and carbon steels in H 2 S solutions was first proposed by Tsujikawa in 1993. H 2 S production was detected in presence of carbon steel corroding in acidified thiosulfate-containing solutions. In this paper, the kinetics of H 2 S evolution are used to estimate the range of partial pressure of H 2 S that can be simulated with thiosulfate solutions. It was determined that acid brines containing 10 −4 M and 10 −3 M S 2 O 3 2− could be used for replacing continuous bubbling of dilute H 2 S/N 2 mixtures in tests of degradation of carbon steels, with H 2 S partial pressures ranging between 0.03 and 0.56 kPa. The kinetics of H 2 S production were compared with the amount of sulfur in side reactions, like formation of iron sulfide films and elemental sulfur.

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mentioning

confidence: 99%

Reaction Paths of Thiosulfate during Corrosion of Carbon Steel in Acidified Brines

Kappes

Frankel

Sridhar³

et al. 2012

J. Electrochem. Soc.

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“…The presence of hydrogen sulfide (H 2 S) in the environment typically results in an increase in the FCGR, with FCGR at high ∆K values being as high as 50 times the values in air. [1][2][3][4][5][6][7] FCGR studies in a range of environments indicate that FCGR increases with increasing H 2 S concentration. 1,[4][5][6][7] The increase in the FCGR with respect to the air value is also affected by ∆K at which the tests are performed.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] FCGR studies in a range of environments indicate that FCGR increases with increasing H 2 S concentration. 1,[4][5][6][7] The increase in the FCGR with respect to the air value is also affected by ∆K at which the tests are performed. Typically, low ∆K leads to a lower increase in the FCGR over air values compared to high ∆K.…”

Section: Introductionmentioning

confidence: 99%

Role of Sour Environments on the Corrosion Fatigue Growth Rate of X65 Pipe Steel

Gui¹,

Thodla²,

Müller³

2012

Corrosion

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Corrosion fatigue of C-Mn steels in sour environments is a concern in various offshore applications, particularly for flowlines and risers. The commonly accepted mechanism of the enhanced fatigue crack growth rate (FCGR) behavior in these environments is hydrogen embrittlement. Hydrogen enters in the metal exposed to a sour environment through corrosion reactions occurring on the metal surface (referred to as bulk-charged hydrogen). During crack propagation, the fresh exposed metal at the crack tip under fatigue loading can also react with the corrosive environment and therefore generate hydrogen (referred to as crack tip hydrogen). Potentially, both of these two sources of hydrogen can impact the FCGR of the pipe steel. In this work, it was found that the bulk-charged hydrogen played a more dominant role in enhancing the FCGR of carbon steel in sour environments. The contribution to the FCGR from the crack tip hydrogen is not appreciable. The interaction of the freshly exposed metal with the corrosive environment could lead to the formation of iron(II) sulfide (FeS) film at the crack tip. This could lead to crack closure and decrease the effective ∆K and thus decrease the FCGR at low frequency, particularly at high H 2 S concentration and low pH environments, which is likely the cause for the observation of a plateau in FCGR in the low-frequency regime for carbon steel in the sour environment. Additionally, the experimental results suggest that although diffusible hydrogen was primarily responsible for the enhanced FCGR in the sour environment, the trapped hydrogen also played some role.

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“…It is expected, for NV F460, that a fatigue limit will not be achieved in a corrosive environment. This would mean that at any fatigue stress level, failure will always happen [2]. In general, at the highest stress levels where fatigue life is shorter, the corrosive environment has less time to play a significant role in the damage of the specimen.…”

Section: S-n Testsmentioning

confidence: 99%

“…Figure 1 shows the difference between an S-N curve in air and in a corrosive environment. Typically, a fatigue limit is absent in corrosive environments [2]. An improved knowledge of the fatigue corrosion life of offshore structures by means of representative laboratory scale experiments can help in expanding the design codes.…”

Section: Introductionmentioning

confidence: 99%

Accelerating corrosion in a laboratory set-up for corrosion-fatigue of offshore steels

Depoortere

Rogge

Micone

et al. 2016

SCAD

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Corrosion-fatigue is a dangerous failure mechanism that is not yet fully understood. Structures subjected to corrosion-fatigue are over conservative in design, which is economically unfavourable. To counter this, representative laboratory experiments simulating the corrosion-fatigue conditions of an offshore structure should be performed. Lab testing is, for obvious reasons, performed at frequencies much higher than these of wave and wind actions. However, this means that corrosion needs to be accelerated in the same manner. In this work two different ways to accelerate corrosion were selected, namely temperature and oxygen content adaptation. S-N curves were determined in different test conditions in order to evaluate the damage evolution. It has been found that high temperatures and high levels of oxygen content will result in earlier failure. The fracture surfaces are somewhat different than fracture surfaces obtained due to fatigue in air. More crack initiation sites can be observed and the fracture surface is generally rougher due to corrosion.

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Corrosion Fatigue of Welded C-Mn Steel Risers for Deepwater Applications: A State of the Art Review

Cited by 10 publications

References 0 publications

Reaction Paths of Thiosulfate during Corrosion of Carbon Steel in Acidified Brines

Reaction Paths of Thiosulfate during Corrosion of Carbon Steel in Acidified Brines

Role of Sour Environments on the Corrosion Fatigue Growth Rate of X65 Pipe Steel

Accelerating corrosion in a laboratory set-up for corrosion-fatigue of offshore steels

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