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Picture for Investigation of Sulfide Stress Crack Propagation Using Sour Pipe Burst in Tubulars with Simulated Defects under Pressure
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Investigation of Sulfide Stress Crack Propagation Using Sour Pipe Burst in Tubulars with Simulated Defects under Pressure

Product Number: 51324-20420-SG
Author: Brian Chambers; Bostjan Bezensek; Sebastian Cravero; Pedro Olivo; Octavio Albores
Publication Date: 2024
$40.00
Seamless oil country tubular goods (OCTG) with defined chemistry and toughness, e.g. API 5CT C110, are utilized as production casing in sour wells globally. These grades must withstand high pressures and mild sour conditions to maintain the integrity of the well and, as such, should resist both sulfide stress crack (SSC) initiation and potential propagation from defects in service. A laboratory study was conducted to assess the tendency of crack propagation from two defined types of defects, electro-discharge machined (EDM) notches and fatigue cracks, simulating potential as-delivered OCTG tubulars. The tubulars were subjected to a variety of test conditions including two temperatures, 4ºC and 24ºC, internal pressures ranging from 550 to 1,100 bar, and exposure to a modified NACE TM0177 Solution B equilibrated with 7% H2S/N2 gas purge. The applied pressure and depth of defects were used to determined applied stress intensity values, K, for each condition to compare tests with one another and to traditional small-scale evaluations per NACE TM0177 Method D, single edge notched tensile (SENT), and constant K compact tension (CT). The findings indicated that tendency towards SSC propagation was principally dependent on type of defect, temperature, and applied K. Threshold K values for SSC propagation from EDM-type defects were higher than determined from any of the small-scale evaluation methods. Fatigue pre-cracks were demonstrated to be more aggressive in promoting SSC propagation compared to EDM-type defects.
Picture for Investigation of the Corrosion Performance of Stainless Steel and Low Alloy Steel Sucker Rod Materials in Aggressive Environments
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Investigation of the Corrosion Performance of Stainless Steel and Low Alloy Steel Sucker Rod Materials in Aggressive Environments

Product Number: 51320-14321-SG
Author: Aleksey Shakhmatov, Oscar Martinez, Robert Badrak, Sergey Kolesov, Rodrigo Barreto, William Howie
Publication Date: 2020
$20.00

The corrosion resistance of sucker rod materials can be a significant concern, especially in aggressive service environments with high acid gas concentrations. Corrosion-related failures have been associated with increased levels of produced hydrogen sulfide (H2S) and carbon dioxide (CO2). The presence of corrosion damage, which is characterized by local material dissolution and pitting formation under the influence of CO2 and/or H2S, provides the initiation sites in a fatigue cracking mechanism. The fatigue crack propagation in corrosion aggressive environments is associated with the following factors: (1) local tensile stress concentration at crack tip, and (2) local corrosion dissolution. Therefore, using a material that tends to re-passivate as it interacts with the environment would be the optimum solution in order to mitigate the likelihood of field failures and reduce overall operating costs. Regarding passive film disruption processes abrasion and high temperature influences were not considered at this stage of the present study and repassivation kinetics were not measured. Conventional sucker rod production processes include normalize and temper (N&T) or quench and temper (Q&T) heat treatments to meet desired strength levels of low alloy steels. In order to enhance the corrosion properties and provide a resistant sucker rod solution, 13Cr martensitic stainless steel may provide a viable alternative to low alloys steels. This paper focuses on the characterization of 13Cr sucker rod material by comparing the general corrosion and corrosion fatigue performance with low-alloy steels.