New Cathodic Protection Criteria Based on Direct and Alternating Current Densities Measured Using Coupons and Their Application to Modern Steel Pipelines

CORROSION ◽  
2004 ◽  
Vol 60 (3) ◽  
pp. 304-312 ◽  
Author(s):  
Y. Hosokawa ◽  
F. Kajiyama ◽  
Y. Nakamura
Keyword(s):  
Cathodic Protection ◽  
Field Tests ◽  
Alternating Current ◽  
Pipe Material ◽  
Review Of The Literature ◽  
Density Measurements ◽  
Corrosion Risk ◽  
Ac Current ◽  
Current Densities ◽  
Dc Current

Abstract The risks of alternating current (AC) corrosion, overprotection, and stray direct current (DC) corrosion are increasing on cathodically protected buried steel pipelines due to the recent changes in factors such as burial conditions, the characteristics of coatings, and pipe material. In the present study, field tests as well as a review of the literature on these risks were conducted. As a result, it has been revealed that there is a certain limitation to assess these risks with respect to conventional cathodic protection (CP) criteria based on pipe-to-soil potential. Therefore, new CP criteria for the elimination of these risks have been developed based on DC and AC current density measurements on coupons. The effectiveness of the new CP criteria was evaluated through the design of CP systems on newly constructed pipelines subject to the risks of AC corrosion, overprotection, and stray DC corrosion. Using these new CP criteria, the design and installation of CP systems as well as the elimination of these risks were completed successfully. The risks of overprotection as well as stray DC corrosion were eliminated by providing an appropriate level of DC current from CP rectifiers. The elimination of the AC corrosion risk was accomplished using distributed magnesium anodes and solid-state DC decoupling devices. Finally, the new CP criteria were proven to be effective in eliminating the risks of AC corrosion, overprotection, and stray DC corrosion on buried steel pipelines.

Corrosion of Pipeline Steel in the Presence of Alternating Current and the New CP Recommendation

2010 ◽  
Author(s):  
A. Q. Fu ◽  
Y. F. Cheng
Keyword(s):  
Corrosion Rate ◽  
Current Density ◽  
Cathodic Protection ◽  
Pitting Corrosion ◽  
Pipeline Steel ◽  
Alternating Current ◽  
National Association ◽  
Ac Current ◽  
Ac Interference ◽  
Full Protection

The alternating current (AC)-induced corrosion of a cathodically protected X65 pipeline steel was studied in a high pH, concentrated carbonate/bicarbonate solution. Results demonstrated that the corrosion rate of the steel increases with the AC current density, and AC interference could increase the pitting corrosion of the steel. In the absence of AC interference or at a low AC current density, i.e., 20 A/m2, a cathodic protection (CP) potential of −950 mV(Cu/CuSO4 electrode, CSE), which is 100 mV more cathodic than −850 mV(CSE) recommended by National Association of Corrosion Engineers (NACE), provides a full protection over the steel. When the AC current density is higher than 20 A/m2, the NACE-recommended CP is incapable of protecting the pipeline from corrosion. A new CP standard is thus developed for recommendation to industry to avoid AC corrosion of pipelines.

A Real-Time AC/DC Measurement Technique for Assessment of AC Corrosion of Buried Pipelines

2012 ◽  
Author(s):  
Cindy X. Su ◽  
Luyao Xu ◽  
Frank Y. Cheng
Keyword(s):  
Real Time ◽  
Current Density ◽  
Steel Surface ◽  
Steel Corrosion ◽  
Buried Pipelines ◽  
Total Potential ◽  
Ac Current ◽  
Potential Alternative ◽  
Current Densities ◽  
Ac Interference

In this work, a real-time AC/DC signal data acquisition (DAQ) technique was developed, which is capable of separating the DC and AC potential components from the recorded total potential, providing mechanistic information about the steel corrosion in the presence of AC interference. It was found that the corrosion of the steel is enhanced by the applied AC current density from 0 to 400 A/m2. With the further increase to 600 A/m2 and 800 A/m2, the corrosion rate of the steel decreases, which is attributed to passivation of the steel at sufficiently high AC current densities, and a compact film is formed on the steel surface. Moreover, the derived mathematic relationships between AC potential and AC current density provides a potential alternative to determine AC current density on pipelines based on measurements of AC potential in the field.

scholarly journals PENGEMBANGAN ALAT UKUR BATAS KAPASITAS TAS SEKOLAH ANAK BERBASIS MIKROKONTROLER

2020 ◽  
Vol 1 (1) ◽  
pp. 14-22
Author(s):  
Novia Utamu Putri ◽  
Putri Oktarin ◽  
Risky Setiawan
Keyword(s):  
Elementary School ◽  
Elementary School Students ◽  
School Children ◽  
Input Voltage ◽  
Wearable Device ◽  
School Students ◽  
Ac Current ◽  
Safe Limit ◽  
Dc Current ◽  
Made In

Backpacks are often used by school children as a container or a place to carry their school materials and equipment, so these types of backpacks are very popular with school children. The large number of students wearing backpacks to school can be proven from the results of a survey conducted at SD N Bumisari, Natar District, South Lampung. Of the total number of subjects, 456 elementary school students carried 404 students (88.6%), and 52 students (11.4%) carried sling bags. But they rarely pay attention to the weight of the burden on the bag he carries everyday which turns out to cause injury to back pain.The tool is made in the form of a wearable device where the tool is in the form of a backpack that can be carried anywhere without having to require AC current as input voltage to the tool, because the power uses DC current with a voltage of 5V, the device is made using a microcontroller supported by a 10 kg loadcell sensor, modules HX711, keypad, plus an indicator component in the form of a buzzer. If the bag load exceeds the safe limit, the buzzer indicator will sound.

Microstructure Evolution During Alternating-Current-Induced Fatigue

Materials ◽  
2004 ◽  
Author(s):  
R. R. Keller ◽  
R. H. Geiss ◽  
Y.-W. Cheng ◽  
D. T. Read
Keyword(s):  
Electron Backscatter Diffraction ◽  
Failure Process ◽  
Low Frequency ◽  
Surface Damage ◽  
Alternating Current ◽  
Fiber Texture ◽  
Electrical Failure ◽  
Damage Process ◽  
Current Densities ◽  
Interconnect Lines

Subjecting electronic interconnect lines to high-density, low-frequency alternating current creates cyclic thermomechanical stresses that eventually cause electrical failure. A detailed understanding of the failure process could contribute to both prevention and diagnostics. We tested unpassivated Al-1Si traces on the NIST-2 test chip; these are 3.5 μm wide by 0.5 μm thick by 800 μm long, with a strong (111) as-deposited fiber texture and an initial average grain diameter of approximately 1 μm. We applied rms current densities of 11.7 to 13.2 MA/cm2 at 100 Hz. Resistance changes in the lines indicated that such current densities produce temperature cycles at 200 Hz with amplitude exceeding 100 K. Open circuits occurred in under 10 minutes, with substantial surface damage seen after only one minute. A few failures initiated at lithography defects initially present in the lines, but most were produced by the current alone. In one detailed example presented in this paper, we monitored the damage process by interrupting the current at 10, 20, 40, 80, 160, and 320 s in order to characterize an entire line by scanning electron microscopy and automated electron backscatter diffraction (EBSD); failure took place after 697 s. Results are described in terms of deformation, grain growth, and orientation changes.

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