Kinetics and Characterisation of Calcareous Deposits under Cathodic Protection in Natural Sea Water

1998 ◽  
Vol 289-292 ◽  
pp. 1163-1180 ◽  
Author(s):  
C. Deslouis ◽  
A. Doncescu ◽  
D. Festy ◽  
O. Gil ◽  
V. Maillot ◽  
...  
Keyword(s):  
Cathodic Protection ◽  
Sea Water ◽  
Calcareous Deposits

An Initial Investigation of Calcareous Deposits upon Cathodic Steel Surfaces in Sea Water

CORROSION ◽  
1981 ◽  
Vol 37 (2) ◽  
pp. 70-76 ◽  
Author(s):  
S. L. Wolfson ◽  
W. H. Hartt
Keyword(s):  
Current Density ◽  
Cathodic Protection ◽  
Sea Water ◽  
Cathodic Current Density ◽  
Water Velocity ◽  
Cathodic Current ◽  
Cathodic Potential ◽  
Electrolyte Flow ◽  
Calcareous Deposits ◽  
Steel Surfaces

Abstract The influence of potential and nominal sea water velocity upon the nature of calcareous deposits formed upon a cathodic steel surface has been investigated. Specific attention was focused upon change with exposure time of the current density to maintain a prescribed cathodic potential and upon thickness of the calcareous film. Equations have been developed whereby pH of the electrolyte adjacent to both a filmed and film-free surface can be rationalized in terms of cathodic current density and character of the electrolyte flow. Structure of calcareous deposits was investigated by scanning electron microscopy. Results are discussed within the frame of current understanding of marine cathodic protection and cathodic protection practices.

scholarly journals Cathodic protection of structures in seawater using solar panels

2019 ◽  
Vol 121 ◽  
pp. 02004
Author(s):  
Boris Borisovich Chernov ◽  
Van Mung Vu ◽  
Anac Maskharovich Nugmanov ◽  
Lyudmila Yuryevna Firsova
Keyword(s):  
Cathodic Protection ◽  
Sea Water ◽  
Cathode Current Density ◽  
Complete Agreement ◽  
Low Alloy Steels ◽  
Solar Panels ◽  
Protective Properties ◽  
Theoretical Concepts ◽  
Alloy Steels ◽  
Cathode Current

It is well known that the cathodic protection of structures in seawater is accompanied by the formation of calcareous deposits on them. In current study, we consider the physicochemical modelling of the formation of the deposit composition against cathode current density in seawater. The reliability of the model representations is confirmed by direct experiments. The work also studied the protective properties of the deposits with a different composition for low-alloy steels in natural sea water. It has been shown that the deposits of pure Mg(OH)2 and the deposits of CaCO3 + Mg(OH)2 had better protective ability against corrosion than the deposits of pure CaCO3. However, the deposits of Mg(OH)2 dissolved faster than the deposits of CaCO3 and CaCO3 + Mg(OH)2. Theoretical concepts and experiments on the laws governing the formation of the deposits and their protective properties are in complete agreement with each other. This allows to use the obtained patterns in the cathodic protection of structures in sea water using solar panels, forming standard deviations with predetermined protective properties in the daytime.

Calibration of the AC Potential Dropping System (ACPD) for Determination of Crack Growth in API 5L X65 Steel under Cathodic Protection Effect

2020 ◽  
Vol 1012 ◽  
pp. 412-417
Author(s):  
Misael Souto de Oliveira ◽  
Antonio Almeida Silva ◽  
Marco Antonio dos Santos ◽  
Jorge Antonio Palma Carrasco ◽  
João Vitor de Queiroz Marques
Keyword(s):  
Crack Growth ◽  
Marine Environment ◽  
Cathodic Protection ◽  
Sea Water ◽  
Potential Drop ◽  
Mechanical Tests ◽  
Flow Density ◽  
Type Specimens ◽  
X65 Steel ◽  
Api 5L X65 Steel

In this work the calibration of an Alternative Current Potential Drop (ACPD) system was performed to monitore laboratory mechanical tests on marine environment under cathodic protection. The calibration was done on CT type specimens of API 5L X65 steel dimensioned according to ASTM E1820 standard., The crack propagation during a tensile test with displacement control in an ACPD equipment was monitored through the performs points collection by two channels: one that monitors the crack growth and another that monitors a region free of crack. Using a profile projector and graphical data processing and analysis software, the area of ​​the fracture surface of the specimen was meansured, which allowed to correlate a crack size with a corresponding value of potential drop and the calibration curve. In order to verify verify the efficacy and precision of the technique, step loading tests were performed on API 5L X65 steel test specimens, submerged in synthetic sea water under the overprotection potential of-1300mVAg/AgCl. The results of the calibration showed few dispersed errors, and the main factors of this dispersion may be related to the geometry of the specimen and with variations in current flow density, which is influenced by corners and edges and by the presence of pick-up inductive. The calibration and its effectiveness can be verified through the results of the tests in marine environment, presenting crack lengths close to the actual values, confirming the effectiveness of the ACPD technique.

Fracture Mechanics Integrity Assessment of Stud Bolts Subjected to Cathodic Protection

2020 ◽  
Author(s):  
Mario A. L. de Castro ◽  
Fabio Alves ◽  
Kumarswamy Karpanan ◽  
Anand Venkatesh
Keyword(s):  
Fracture Mechanics ◽  
Cathodic Protection ◽  
Atomic Hydrogen ◽  
Sea Water ◽  
Circular Crack ◽  
Relative Increase ◽  
Maximum Increase ◽  
Integrity Assessment ◽  
Thread Root ◽  
Metallic Parts

Abstract Exposure of metallic parts to cathodic protection (CP) in sea water leads to production and diffusion of atomic Hydrogen into the metal matrix. Absorption of atomic Hydrogen into the metal could lead to hydrogen embrittlement (HE). In order to study the influence of stresses related to HE, FEA and Fracture Mechanics (FM) assessments were performed on a stud bolt threaded geometry. Effects of manufacturing tolerances, interface between nut and stud bolt and a defect in the form of a semi-circular crack placed in highest stress location of a thread root were also considered. Investigations of stress profiles when tension or bending are applied in test samples for measurement of HE threshold were also done, aiming at showing gaps on ASTM F1624-12 [1]. Tolerance assessment shows a relative maximum increase of 260% of nominal linearized membrane plus bending (NLMB) stresses regarding the nut runout [2] and for the proprietary nut geometry, such relative increase drops to 126% of NLMB stresses. Highest Hydrogen concentrations could be observed in the neighborhood of the first loaded thread root. FEA of cracked geometry shows that Hydrogen concentration could increase by around 283% around the crack tip, when compared to stud bolt in unloaded condition. Integrity assessment according to API 579-1 [3] or BS 7910 [4] and tests conducted according to ASTM F1624-12 [1] show less conservative results.

Reducing Activity and the Formation of Base in the Shore Crab, Carcinus Maenas

1985 ◽  
Vol 65 (2) ◽  
pp. 505-530 ◽  
Author(s):  
Peter S. B. Digby
Keyword(s):  
Outer Surface ◽  
Biological Material ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Water Salinity ◽  
Shore Crab ◽  
Calcareous Deposits ◽  
Reducing Activity ◽  
Diffusion Potentials ◽  
Active Processes

Crustacean cuticle consists essentially of chitin impregnated and coated with protein which is tanned with quinone (Dennell, 1947a). The outer surface is most heavily tanned, and the cuticle is further strengthened by calcification. The various theories as to the mechanism of calcification in crustacean and other biological material have been reviewed briefly by Digby (1967). Most appear unsatisfactory for various reasons, and evidence was outlined that calcification might arise from the formation of base by processes which are essentially electrochemical in origin. The quinone-tanned protein of the cuticle is electrically semiconducting and supports electrode action in suitable gradients of potential (Digby, 1965), and small potential differences may arise by diffusion or by active processes. Thus the deposition of calcareous salts might arise partly at least by action comparable to that which takes place at a metallic cathode. In support of this, the position of the initial calcareous deposits in Carcinus maenas (L.) was found to change with the gradient of sea-water salinity in the manner expected if some control were exercised by diffusion potentials, acting across a thin semiconducting layer to generate small changes of pH (Digby, 1968).

Cathodic Protection of an Active Ship in Sea Water

CORROSION ◽  
1950 ◽  
Vol 6 (7) ◽  
pp. 232-234 ◽  
Author(s):  
K. N. BARNARD ◽  
G. L CHRISTIE
Keyword(s):  
Cathodic Protection ◽  
Sea Water

The Successful Use of Austenitic Stainless Steels in Sea Water

1977 ◽  
Vol 17 (02) ◽  
pp. 101-110 ◽  
Author(s):  
G.E. Moller
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cathodic Protection ◽  
Stainless Steels ◽  
Sea Water ◽  
Austenitic Stainless Steels ◽  
Pump Impeller ◽  
Ocean Science ◽  
Free Service ◽  
Selection Of

Moller, G.E., International Nickel Co., Inc., Torrance, Calif. Abstract Austenitic stainless steels are providing excellent trouble-free service in sea water for pumps, propellers, valves. and other marine equipment. propellers, valves. and other marine equipment. Occasionally, a failure occurs as the result of deep localized pitting in a crevice. Data are given showing that austenitic, ferritic. and martensitic stainless steels suffer pitting in crevices and under deposits in quiescent sea water. Austenitic stainless steels remain free from attack in high-velocity sea water. Low-purity ferritic and the martensitic stainless steels frequently pit in high-velocity sea water. Crevice corrosion can be controlled effectively with cathodic protection from iron, zinc. aluminum or magnesium galvanic anodes or impressed current cathodic protection by polarization to -0.6 v vs Calomel. Austenitic stainless steel performs well in many situations because it is a component of a multi-alloy assembly utilizing iron or steel. Examples from field experience arc given. Introduction During the past decade, there has been a growing use of austenitic stainless steel in marine equipment. Most applications have been successful but an unexpected failure has been observed occasionally. It is the purpose of this paper to describe when and how to use austenitic stainless steel with success. The selection of stainless steels appears to result from the engineering requirements of new, advanced, high-speed, high-reliability commercial, pleasure, and military craft. Ocean science and pleasure, and military craft. Ocean science and engineering, offshore oil production, fishing, and ocean mining are also contributing to the selection of stainless steels for sea-water applications. The increasing use of stainless steel in the marine environment is found in work-boat propellers, pump components, bow thrusters, valves, shafting pump components, bow thrusters, valves, shafting and shaft components, through-hull fittings, parts on data-gathering buoys, fasteners, and housings of oceanographic instruments. When austenitic stainless steel has given good, corrosion-free service, it is most often found to be used as a key component in a multi component, multi-alloy assembly or system receiving the benefit of built-in cathodic protection. For example, in Fig. 1 a cast Type 304 (Alloy Casting Institute CF-4) propeller is being used on a steel seagoing tugboat with zinc anodes attached to the rudder. Fig. 2 shows a cast ACI CE-30 power-plant sea-water circulation-pump impeller free power-plant sea-water circulation-pump impeller free of any corrosion after 6 years of service that was used in combination with an austenitic cast-iron suction bell and diffuser. SPEJ p. 101

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