Damage to flexible pipes of coiled tubing equipment due to corrosion and fatigue: methods and approaches for evaluation

Abstract

Purpose. To propose an engineering approach for evaluating surface corrosion fatigue of flexible pipes of coiled tubing equipment, on the basis of the generalized data about corrosion fatigue behaviour of structural steels and analysis of the existing methods and approaches for assessment of these phenomena.Methods. We applied the original method of corrosion fatigue study which takes into account the parameters of electrochemical dissolution of cyclically deformed surface in conditions of its deformation, as well as the known methods of fracture mechanics, corrosion science, electrochemistry and materials science.Findings. The stages of initial corrosion damaging and surface corrosion fatigue nucleation in structural steels were considered. The criterion ratio for evaluating the period of surface corrosion fatigue crack nucleation that relates the number of loading cycles before crack initiation, the corrosion current, the constants of electrochemical dissolution of metal surface to the cyclic loading parameters is derived. This criterion allowed to obtain and substantiate the experimental formula for predicting the number of loading cycles prior to the surface corrosion fatigue crack nucleation.Originality. The suggested new model describes the surface fatigue crack nucleation as a result of interaction between corrosion and operational cyclic loadings of the coiled tubing equipment flexible pipes.Practical implications. The proposed relationship for calculating macrocrack nucleation period is applicable for engineering assessment of serviceability and fracture risk of flexible pipes of coiled tubing equipment under assigned operating conditions.

Residual Strength Assessment and Residual Life Prediction of Corroded Pipelines: A Decade Review

“…Due to the differences in various evaluation methods in many aspects [54], the calculation results also be affected. In all, 64 groups of data were collected from the literature [12], including 40 groups of low-strength steel grade corrosion pipes (X42, X46-1, X46-2, X46-3, X46-4, X52-1, X52-2, and X56) and 24 groups of medium and high-strength steel grade corrosion pipes (X60, X65, and X80), including defect size parameters, pipe size parameters, material parameters, and burst test pressure.…”

Corrosion resistance of steel for coiled tubing units

“…Given the complexity of the TO, the injection of reagents [10], and compliance with the technology of work, attention is mainly paid to the number of TO. Cases of mechanical or fatigue damage during winding and unwinding are investigated, and much less attention is paid to the issue of corrosion [11][12][13].…”

Stressed State of Chrome Parts During Diamond Burnishing

“…Mining equipment operates under extreme conditions at high temperatures, sign-changing loads and contact loads in aggressive environments containing hard abrasive rock particles during drilling [1-3] and mining [4,5]. Therefore, means are used to increase the service life of the equipment, in particular various wear-resistant and corrosion-resistant coatings are used, which allow to rationally combine the properties of the coating material and the base, in particular, deposit-ed [6][7][8][9], laser [10], formed coating by electric spark alloying method [11,12], formed coating by hybrid ion-plasma discharge system [13] and chrome [14,15].…”