Corrosion Fatigue Behavior of Flexible Pipe Tensile Armor Wires in a CO&lt;sub&gt;2&lt;/sub&gt; Environment

Santos, Fábio Pinheiro; Pires, Fábio Ramôa; Clements, Richard; Clevelario, Judimar; Sheldrake, Terry; Souza, Luís Felipe Guimarães de; Kenedi, Paulo Pedro

doi:10.4028/www.scientific.net/msf.758.77

Cited by 2 publications

(2 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…28, 37,38 Experiments revealed 37 that by exposing samples to corrosive CO 2 environment, the time to failure is *10-50 times shorter compared to the fatigue life in air conditions. The results showed 37,39 that the fatigue life decreased as a function of CO 2 partial pressure, and the effect of CO 2 content was more evident at lower stress ranges, such as 400 MPa. 37 Both pH and the composition of the electrolyte play an important factor in corrosion fatigue mechanisms.…”

Section: Vol Nomentioning

confidence: 98%

“…42,43 Only few publications detail on the corrosion fatigue data in an aqueous CO 2 environment. [37][38][39][44][45][46] The publications are based on limited datasets, while detailed analysis of the impact of corrosion mechanisms on the fatigue performance is still not explored. This includes the effect of highly supersaturated solution of Fe 2þ , typically found in annulus conditions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO₂environment

Rogowska

Gudme

Rubin

et al. 2016

Corrosion Engineering, Science and Technology

View full text Add to dashboard Cite

In this work, the corrosion fatigue behaviour of steel armours used in the flexible pipes, in aqueous solutions initially containing different concentrations of Fe 2þ , was investigated by four-point bending testing under saturated 1 bar CO 2 condition. Corrosion fatigue results were supported with ex situ measurements of Fe 2þ and pH. Characterisation of the corrosion scales and crack formations was performed using microscopic and diffraction techniques. Fatigue results showed two times better fatigue life, at the stress ranges of 250 MPa, for samples tested in solutions containing the concentration of Fe 2þ marginally above the solubility limit of FeCO 3 compared to the samples tested in highly supersaturated solution of Fe 2þ. Results revealed that the impact of the alternating stresses on the corrosion behaviour of samples reduces with lowering the applied stresses. At the stress range of 100 MPa, fatigue samples experienced the same corrosion rate as samples that were not subjected to dynamic loading.Keywords: Carbon steel, Carbon dioxide, Corrosion fatigue, Supersaturation, Iron carbonate IntroductionFlexible pipes, which are used in the oil and gas industry, are an attractive alternative to rigid pipes due to their shorter installation times and longer durability. The typical structure of flexible pipes is composed of polymeric and steel layers, which are not bonded together, to ensure the flexibility of the pipe. 1 The fatigue life of a flexible pipe is determined by the fatigue life of the steel armours, which is placed in the annular space between the inner liner and outer sheath. It was reported 2 that the fatigue life of tensile armour depends on the applied stresses, which are generated due to waves and water current, and the corrosive operating environment. The annulus region might be water filled either due to diffusion and condensation of water from the bore or as a result of a breakage of the outer sheath allowing the entry of sea water. In addition, the severity of the corrosion environment may be increased due to diffusion of small molecules such as methane (CH 4 ), carbon dioxide (CO 2 ) and hydrogen sulphide (H 2 S) from the pipe bore through the inner liner into the annulus.1-3 However, due to a low ratio of free water volume (V) to steel surface area (S), typically v0.1 mL cm 22 , 3 a rapid, high supersaturation of Fe 2þ in the liquid is possible. As a consequence, low corrosion rates, usually v10 mm year 21 , are achieved. 3,4The corrosion behaviour of steel in aqueous CO 2 solution is influenced by the formation of protective films, which might decrease their corrosion rate. 5,6 Typical corrosion scales, formed in such an environment, consist of iron carbonate (siderite, FeCO 3 ) and undissolved cementite (Fe 3 C).7,8 A large number of environmental variables, such as pH, 9-11 temperature, 9,12,13 partial pressure 11 and flowrate, 14-17 influence the corrosion behaviour of steel. Further, material characteristics such as microstructure, chemical composition and heat treatment condition [...

show abstract

Section: Vol Nomentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO₂environment

Rogowska

Gudme

Rubin

et al. 2016

Corrosion Engineering, Science and Technology

View full text Add to dashboard Cite

show abstract

Experimental Evaluation of KIEAC of a Carbon Steel Using the Pin-Loaded SENT Geometry

Teixeira Oliveira de Menezes,

Braun Poloponsky,

Castrodeza

2023

Journal of Testing and Evaluation

View full text Add to dashboard Cite

The experimental determination of the threshold stress intensity factor for environment-assisted cracking (KIEAC) is described by several standards, which allow the use of different specimen geometries and methodologies for crack length estimation. In some cases, the combination of structure, specimen size, or both, main loading direction, and crack orientations of the component that need to be characterized limit the use of standardized geometries. Consequently, alternative geometries must be used. In this study, fatigue pre-cracked pin-loaded single edge notched tension specimens as defined by BS 8571:2018, Method of Test for Determination of Fracture Toughness in Metallic Materials Using Single Edge Notched Tension (SENT) Specimens, were applied for the experimental evaluation of the KIEAC of a carbon steel. The specimens were tested in deaerated substitute ocean water solution saturated with carbon dioxide at 40°C and at 1 and 10 bar (100 and 1,000 kPa) under constant load conditions with incremental (step) loading. The crack length during the tests was monitored by direct current potential drop, which was helpful for defining the applied K corresponding to the onset of subcritical crack growth (KIEAC). Additionally, fractographic analysis of KEAC specimens and results from the fracture toughness evaluation of this material in air at room temperature have also been reported.

show abstract

Corrosion Fatigue Behavior of Flexible Pipe Tensile Armor Wires in a CO<sub>2</sub> Environment

Cited by 2 publications

References 9 publications

Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO₂environment

Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO₂environment

Experimental Evaluation of KIEAC of a Carbon Steel Using the Pin-Loaded SENT Geometry

Contact Info

Product

Resources

About

Corrosion Fatigue Behavior of Flexible Pipe Tensile Armor Wires in a CO<sub>2</sub> Environment

Cited by 2 publications

References 9 publications

Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO2environment

Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO2environment

Experimental Evaluation of KIEAC of a Carbon Steel Using the Pin-Loaded SENT Geometry

Contact Info

Product

Resources

About

Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO₂environment

Effect of Fe ion concentration on fatigue life of carbon steel in aqueous CO₂environment