Under-deposit corrosion

Electrochemical Study on the Macro-Cell Corrosion of Pipeline Steel Partially Covered by Different Kinds of Mineral Deposits

“…A square plastic groove was placed in the top left corner of the WBE, covering 5 rows and 5 columns, allowing for the addition of mineral deposits up to a depth of 10 mm. The ratio of the bare steel area and deposit covered area was 3:1, which simulates the normal UDC conditions in real pipelines. , The measurement principle of the WBE has been introduced in previous studies . Both the open circuit potential (OCP) and macro-cell current distributions on the WBE were mapped by the electrochemical instrument (YC-2200A, YunChi), which consists of a high voltage meter, multichannel zero resistance ammeters (ZRA) and a multiplexer.…”

“…As reported in the literature, the oil and gas industries commonly encounter deposits composed of silica sand, calcium carbonate, alumina, corrosion products, organic compounds, etc. 2,3,24 As the major deposits in pipelines, silica sand, calcium carbonate, and alumina might greatly influence the corrosion process of UDC in pipelines. In this work, these three major types of mineral deposits found in pipelines were employed to investigate the macro-cell current between deposit-covered area and bare steel area using the WBE technique in a CO 2containing solution.…”

“…The mineral deposits always entrain in the oil and gas production water, − resulting in the partial coverage of the pipe bottom. The accumulation of the mineral deposits might cause localized corrosion at six o’clock of the pipe circle, , which is normally defined as under deposit corrosion (UDC). , Due to the inhibition of the ion diffusion beneath the deposition barrier, the local chemical and electrochemical environment beneath the deposit would be different from that of the steel in the bulk solution. , Accordingly, the inhomogeneous surface status beneath the deposit , and the potential difference , between the bare steel and deposit-covered steel are attributed to the main influencing factors for the initiation and propagation of UDC.…”

“…The macro-cell corrosion induced by deposits occurs as a result of the potential difference between the deposit-covered steel and bare steel. , Once the deposit-covered electrode acted as the anode, the localized corrosion would be more serious along with the increase of the ratio between the bare steel area and the deposit-covered area. ,, In order to quantify the localized corrosion, Tan et al first used the wire beam electrode (WBE) technique to monitor the corrosion process of UDC. In this test, the surface of WBE was partially covered by SiO 2 particles to monitor galvanic current and corrosion potential distribution.…”

Effect of deposit chemistry on microbial community structure and activity: Implications for under-deposit microbial corrosion

“…Production fluids from oil and gas pipelines can carry different solid compounds including corrosion products, silt, sandstone, and solids from the formation reservoir ( Brown and Moloney, 2017 ). During periods of low or intermittent flow, solid particles can sediment and form recalcitrant scales over the horizontal surfaces of the assets.…”