Study The Effect Of Liquid Impingement Corrosion/Erosion With And Without Solid Particles On Two Pipeline Grades Api X65 and Mild Steel Aisi 1030
Ihsan-ul-Haq Toor, حافظ مزمل إرشاد
كلية الهندسة-جامعة الملك فهد للبترول والمعادن · السعودية
In this study, the impingement corrosion and erosion-corrosion characteristics of two types of carbon steel alloys due to liquid jet impingement were investigated. The study was focused on the effect of jet velocity and jet angle on the rate of impingement erosion-corrosion with and without the solid particles of size ranging from 125μm-704μm (means size of 314 μm). Fluid impingement on fluid handling equipments at high velocities results in severe impingement erosion-corrosion issues in different industries. The impingement erosion-corrosion behavior of carbon steel AISI 1030 and API 5L- X65 was investigated experimentally taking into consideration the effect of velocity and different impingement angels (e.g. 15°, 30°, 45°, 60°, & 90°) in 0.2M NaCl solution for twenty four hours.The maximum impingement erosion-corrosion rate was observed at 45° in three different velocities (i.e. 3, 6 & 12 m/s). This maximum erosion-corrosion rate is resulted to the combined effect of shear stress and impact stress on the specimen surface during the test. At lower angles (15°-30°) shear stress was dominant and at higher angles (60°-90°) normal impact stress was dominant. However, there was a balance between these two stresses at 45°, which resulted in the peak impingement erosion-corrosion rate with the deepest wear scar (57μm deep). The wear scar depth in high velocity regions, (near impingement zone) was visualized by optical profilometer. It was observed that with an increase in velocity, the impingement erosion-corrosion rate was also increased.Impingement erosion-corrosion mechanism was analyzed using SEM of the eroded surfaces. Observations of the SEM micrographs, demonstrated that, the recessed scars were formed in the direction of fluid flow. At lower angles (15º-30º) the shallow-elongated ploughing, plastic deformation, raised lips followed by flattening of the ridges were observed. Whereas, at intermediate angles, deep ploughing and deep craters were found. However dimples, micro-forging, extrusion, platelet formation and their removal were identified as dominant mechanisms at 90° angle in the impingement erosion-corrosion experiments.