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Title: Cathodic protection requirements for deepwater systems

Abstract

Field and laboratory experience related to requirements for cathodic protection (CP) in deep water are reviewed with emphasis on identification of the major variables that need to be specified for successful deepwater CP designs for offshore structures. The subject is addressed based on the historical development of cathodic protection design methodologies for offshore structures focusing on sacrificial anode systems and trends that have resulted in specific changes in design requirements. Three main subjects are discussed: (1) application of existing industry standards such as NACE RP0176; (2) environmental factors--dissolved oxygen, temperature, salinity, pH, water velocity and fouling; and (3) calcareous deposits--difference between shallow and deep waters. Current practice of design criteria and systems for deepwater applications is assessed, including initial polarization, use of coatings and anode materials. The results from laboratory tests are compared with available documented service experiences and field tests results.

Authors:
; ; ;
Publication Date:
Research Org.:
InterCorr International, Inc., Houston, TX (US)
OSTI Identifier:
20005848
Resource Type:
Conference
Resource Relation:
Conference: Designing Cathodic Protection Systems for Marine Structures and Systems, Norfolk, VA (US), 11/03/1998; Other Information: PBD: 1999; Related Information: In: Designing cathodic protection systems for marine structures and vehicles. ASTM special technical publication 1370, by Hack, H.P. [ed.], 119 pages.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; CATHODIC PROTECTION; EQUIPMENT PROTECTION DEVICES; DESIGN; SEAWATER; DEPTH; OFFSHORE PLATFORMS; MATERIALS

Citation Formats

Menendez, C.M., Hanson, H.R., Kane, R.D., and Farquhar, G.B. Cathodic protection requirements for deepwater systems. United States: N. p., 1999. Web.
Menendez, C.M., Hanson, H.R., Kane, R.D., & Farquhar, G.B. Cathodic protection requirements for deepwater systems. United States.
Menendez, C.M., Hanson, H.R., Kane, R.D., and Farquhar, G.B. Thu . "Cathodic protection requirements for deepwater systems". United States. doi:.
@article{osti_20005848,
title = {Cathodic protection requirements for deepwater systems},
author = {Menendez, C.M. and Hanson, H.R. and Kane, R.D. and Farquhar, G.B.},
abstractNote = {Field and laboratory experience related to requirements for cathodic protection (CP) in deep water are reviewed with emphasis on identification of the major variables that need to be specified for successful deepwater CP designs for offshore structures. The subject is addressed based on the historical development of cathodic protection design methodologies for offshore structures focusing on sacrificial anode systems and trends that have resulted in specific changes in design requirements. Three main subjects are discussed: (1) application of existing industry standards such as NACE RP0176; (2) environmental factors--dissolved oxygen, temperature, salinity, pH, water velocity and fouling; and (3) calcareous deposits--difference between shallow and deep waters. Current practice of design criteria and systems for deepwater applications is assessed, including initial polarization, use of coatings and anode materials. The results from laboratory tests are compared with available documented service experiences and field tests results.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jul 01 00:00:00 EDT 1999},
month = {Thu Jul 01 00:00:00 EDT 1999}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

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  • Increasing interest in deep water offshore areas has presented a whole set of new unsolved problems to the corrosion industry. Several programs are in progress which are attempting to formulate revised cathodic protection design criteria for the deep ocean. The lack of historical data, combined with the increased criticality of accurate corrosion control design in these areas, serve to accentuate the need to be able to monitor the performance of the cathodic protection system once installed. The structural designs being considered for deep water production also present new problems which cannot always be addressed with standard monitoring methods and technologies.more » This paper identifies some of these problems and offer some generic solutions which should serve to increase the overall reliability of future deep water corrosion control systems.« less
  • A computer aided engineering (CAE) tool for marine cathodic protection analyses is described in this paper. The method, called the integral equation method or the boundary element method, is based on the solution of Green's third formula. The procedure of this approach involves three steps, the model generation, the solution of Green's third formula and the examination of the potential distribution on the structure surface. The procedure is described in detail. The merits of this method, compared with the conventional approach in cathodic protection, are discussed. Potential applications and limitations of this method are given.
  • Final design, engineering, installation and commissioning of the largest offshore impressed current cathodic protection retrofit ever undertaken is described. The project was completed using tensioned steel supporting ropes with tubular mixed metal oxide anodes. Each of the four platforms in the complex was protected with 10 tensioned assemblies for a maximum design current output per platform of 5250 amps. Installation was completed in one month; the system is operating at 70% of design capacity with uniform protection.
  • Cathodic protection is an important method of protecting structures and ships from the corrosive effects of seawater. Poor designs can be far more costly to implement than optimal designs, Improper design can cause overprotection, with resulting paint blistering and accelerated corrosion of some alloys, underprotection, with resultant structure corrosion, or stray current corrosion of nearby structures. The first ASTM symposium specifically aimed at cathodic protection in seawater was intended to compile all the criteria and philosophy for designing both sacrificial and impressed current cathodic protection systems for structures and vehicles in seawater. The papers which are included in this STPmore » are significant in that they summarize the major seawater cathodic protection system design philosophies. Papers have been processed separately for inclusion on the database.« less
  • The question answered in this study is whether the demand on a cathodic protection system will change when the protected pipe material is changed from copper-nickel to alloy 625. Two piping mockups were designed to simulate a probable geometry for a cathodically-protected piping system. Each mockup consisted of a 20-foot (610-cm) length of nominal 2-inch (5-cm) diameter piping with a zinc anode for cathodic protection inserted in the discharge end of each. one mockup was made with 70-30 copper-nickel pipe and the other with alloy 625 pipe. Protection currents and potential profiles inside the pipes were measured over a six-monthmore » exposure period in natural seawater flowing at 7-ft/s (210-cm/s). The total protection current and sacrificial anode consumption for alloy 625 pipe was half that for copper-nickel pipe. This means that replacing copper-nickel pipe with alloy 625 pipe in areas close to cathodically-protected heat exchangers or hulls will result in a more conservative design for the cathodic protection system than was the case for the original copper-nickel piping.« less