Telluric Current Effects on Cathodic Protection Potential Measurements on Subsea Pipelines

1982 ◽  
Author(s):  
Clark P. Weldon ◽  
Adam P. Schultz ◽  
Michael T.S. Ling
Keyword(s):  
Cathodic Protection ◽  
Protection Potential ◽  
Subsea Pipelines

Fatigue-Corrosion of High Strength Steels in Synthetic Seawater under Cathodic Protection

2020 ◽  
Vol 841 ◽  
pp. 294-299
Author(s):  
Sergio Lorenzi ◽  
Cristian Testa ◽  
Marina Cabrini ◽  
Francesco Carugo ◽  
Luigi Coppola ◽  
...  
Keyword(s):  
Cathodic Protection ◽  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Loading Frequency ◽  
Offshore Pipelines ◽  
Synthetic Seawater ◽  
Steel Grades ◽  
Protection Potential ◽  
Fatigue Corrosion

The paper is aimed to the study of the corrosion-fatigue behavior of high strength steels for offshore pipelines. Tests have been performed in order to study fatigue crack growth in synthetic seawater under cathodic protection. The tests have been carried out on three different steel grades from 65 to 85 ksi with tempered martensite and ferrite-bainite microstructures. The effect of stress intensity factor, cathodic protection potential and cyclic loading frequency is shown.

Cathodic protection criteria of low alloy steel in simulated deep water environment

2020 ◽  
Vol 67 (4) ◽  
pp. 427-434
Author(s):  
Haijing Sun ◽  
Weihai Xue ◽  
Jiaxin Xu ◽  
Guoliang Chen ◽  
Jie Sun
Keyword(s):  
Shallow Water ◽  
Alloy Steel ◽  
Deep Water ◽  
Cathodic Protection ◽  
Water Environment ◽  
Deep Ocean ◽  
Low Alloy Steel ◽  
Content Type ◽  
Offshore Industry ◽  
Protection Potential

Purpose The purpose of this work is to provide theoretical guidance and experimental analysis for optimized cathodic protection (CP) design of low alloy steel in deep water environments. Design/methodology/approach In the present study, the CP criteria of 10Ni5CrMoV low alloy steel were investigated in a simulated deep water environment (350 m) regarding the theoretical protection potential and measured protection potential. The influences of hydrostatic pressure (HP) and temperature were also discussed in detail. The theoretical protection potential was analyzed with the Nernst equation, and the measured minimum protection potential was derived by extrapolating the Tafel portion of anodic polarization curves. Findings The results indicate that the minimum protection potential of low alloy steel shifts to a positive value in a deep-ocean environment. This can be attributed to the combined effects of HP and the temperature. Moreover, the temperature has a stronger influence compared with HP. The results suggest that the CP potential criteria used in shallow water are still applicable in the deep ocean, which is further confirmed through the SEM and x-ray diffraction analysis of the corrosion products resulted from the potentiostatic cathodic polarization experiments at −0.85 VCSE. Originality/value In recent decades, successful applications of CP for long-term corrosion protection of the steel components applied at a subsea level have enabled the offshore industry to develop reliable and optimized CP systems for shallow water. However, differences in the seawater environment at greater depths have raised concerns regarding the applicability of the existing CP design for deeper water environments. Hence, this research focuses on the CP criteria of low alloy steel in simulated deep water environment concerning the theoretical protection potential and measured protection potential. The influences of HP and temperature were also discussed.

Modeling of Impressed Current Cathodic Protection Anode Arrangements for Storage Tank Bottoms

2011 ◽  
Author(s):  
Robert Adey ◽  
John Baynham ◽  
Cristina Peratta
Keyword(s):  
Cathodic Protection ◽  
Economic Consequences ◽  
Design Concepts ◽  
Modeling Methodology ◽  
Protection Systems ◽  
Gas Products ◽  
Impressed Current ◽  
Protection Potential ◽  
The Cost ◽  
Impressed Current Cathodic Protection

Above ground tanks are frequently used for the storage of Oil & Gas products and they can present a challenge to design an optimum corrosion control system. The base of the tank lies on or near the surface of the ground and is in contact with the material used to support the tank and therefore presents a corrosion challenge. One method of protecting the bottom of a tank is by use of an impressed current cathodic protection (ICCP) system. There are a number of types of Cathodic Protection systems which are designed to protect the tank base in these circumstances. The details of the design of such a system are very important for optimal performance and also the cost, if a number of such systems are to be installed The consequence of a poor design can be uneven distribution of protection potential on the tank base or in the worst cases regions where corrosion of the tank base can take place. An over designed system on the other hand can have significant economic consequences both in terms of installation cost and running costs. Computer modeling is now widely used to optimize CP Designs and verify that the design of the cathodic protection (CP) system meets the design requirements. In this paper a modeling tool is presented which enables corrosion engineers to evaluate the performance of tank base CP systems by predicting the protection provided to the tank for a given CP design. The paper describes and discusses all aspects of the modeling methodology, which it then applies to several different design concepts.

scholarly journals Experimental Study on the Influence of AC Stray Current on the Cathodic Protection of Buried Pipe

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Qingmiao Ding ◽  
Yueming Fan
Keyword(s):  
Experimental Study ◽  
Cathodic Protection ◽  
Comprehensive Analysis ◽  
Stray Current ◽  
Buried Pipe ◽  
Ir Drop ◽  
Threshold Length ◽  
Protection Potential ◽  
Ground Potential ◽  
Coating Crack

The size of the damaged area of the coating and its position on the pipeline impacted the cathodic protection potential, and there was a damaged area of the greatest impact value. When damaged area was 300 mm2, the IR drop was the largest, and this situation could easily lead to inadequate protection; when the parallel spacing between pipeline and interference source was unchanged, the measured value curves of cathodic protection potential presented “U” shaped trend with the increasing stray current interference intensity. Under certain parallel spacing between pipeline and interference source, high alternating stray current intensity would cause serious negative offsets, so that the overprotection of the pipeline occurred, and make the coating crack; there was a parallel threshold length. When less than the threshold, the pipe-ground potential increases rapidly with the parallel length increasing. In order to judge whether a pipeline was interference by AC stray current and the risk of stray current corrosion, we should make a comprehensive analysis of the cathodic protection energizing potential, the switch-off potential, AC pipe-soil potential, IR drops, and so on.

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