The Electrochemical Investigation of the Corrosion Rates of Welded Pipe ASTM A106 Grade B

Abstract

Abstract:The aim of this work was to investigate the corrosion rate of welded carbon steel pipe (ASTM (American Society for Testing and Materials) A106 Grade B) by GTAW under the currents of 60, 70, and 80 A. All welded pipes satisfied weld procedure specifications and were verified by a procedure qualification record. The property of used materials was in agreement with the ASME standard: section IX. The welded pipe was used for schematic model corrosion measurements applied in 3.5 wt % NaCl at various flow rates and analyzed by using the electrochemical technique with Tafel's equation. The results showed the correlation between the flow rate and the corrosion rate of the pipe; the greater the flow rate, the higher corrosion rate. Moreover, the welded pipe from the welding current of 70 A exhibited higher tensile strength and corrosion resistance than those from currents of 60 and 80 A. It indicated that the welding current of 70 A produced optimum heat for the welding of A106 pipe grade B. In addition, the microstructure of the welded pipe was observed by SEM. The phase transformation and crystallite size were analyzed by XRD and Sherrer's equation. The results suggested that the welding current could change the microstructure and phase of the welded pipe causing change in the corrosion rate.

Surface Characterization and Corrosion Resistance of 36Cr-Ni-Mo4 Steel Coated by WC-Co Cermet Electrode Using Micro-Electro Welding

“…The lesser corrosion at the spark energy of (AFD250550) came from the complete penetration by using an appropriate power at which NaCl could not achieve deep penetration. The chloride ion residue was decreased and resulted in a lower corrosion rate [43]. In general, the corrosion resistance of the joint is affected by precipitation and grain boundary characteristics [44].…”

“…If some chloride ion remained and eventually accumulated where the specimens were not fully joined, pitting mode corrosion could occur [43]. For the welding with high spark energy (AFD351150), the specimen exhibited over-penetration from high-power welding (Figure 9c), which resulted in extensive corrosion [43]. The lesser corrosion at the spark energy of (AFD250550) came from the complete penetration by using an appropriate power at which NaCl could not achieve deep penetration.…”

“…Since the welding current of sample AFD150510 is less, the coating and substrate incomplete joint (Figure 9a). If some chloride ion remained and eventually accumulated where the specimens were not fully joined, pitting mode corrosion could occur [43]. For the welding with high spark energy (AFD351150), the specimen exhibited over-penetration from high-power welding (Figure 9c), which resulted in extensive corrosion [43].…”

Modified Manganese Phosphate Conversion Coating on Low-Carbon Steel

“…where J corr is the density of the corrosion current (µA cm −2 ), E.W. is the equivalent weight and for low-alloy steel it equals 27.9 g, whereas d is the density of the sample material (7.87 g cm −3 ) [17,18]. The number 0.13 originates from the conversion factor with own unit: mpy/(µAcm) [19].…”

Numerical Simulation and Experimental Confirmation of a Bimetallic Pipe Forming Process

“…Piping systems play a critical role in the transportation of chemicals, both liquids and gases, from one location to another. The residual stress produced in the process of pipe manufacturing accelerates the corrosion, fatigue, and creep failure of pipes [1,2], which cause enormous economic losses. Bimetallic pipes, in which two materials are metallurgically bonded, combine the advantages of corrosion resistance and economic viability, so that they are widely used in petroleum, nuclear power, offshore platforms, and pharmaceutical fields [3].…”