December 2014

2014 has been an exciting year and in this newsletter, we recap on some of the news stories we think you will find of interest. The BEASY offices in the UK and USA will be closed for the Christmas and New Year holidays, but if you would like to learn about any of the items below, or if you have a project which you would like to discuss, please contact us.

With Seasons Greetings from the BEASY team

NACE Corrosion Conference

BEASY participated in a very busy NACE Corrosion Conference in San Antonio and was active in the conference programme and exhibition hall, highlighting corrosion modelling services and software. We are already preparing for the next year's event in Dallas so if you would be interested in arranging a meeting please contact us.

Technical Papers

There were a number of technical papers published at NACE 2014 which featured some engineering projects carried out by the BEASY engineering services team and by customers:

Key Technologies in Regional Cathodic Protection in Oil & Gas Stations

Yanxia Du, Liang Dong, Minxu Lu - Corrosion and Protection Center, University of Science and Technology Beijing, China. Liyang Wang - CNPC Offshore Engineering Company, Ltd. China

General Layout Of The Gas Station
With 12 Anode Groundbeds

Within an oil & gas station, normally different kinds of electrically connected metal structures are cathodically protected as a whole to protect them from corrosion. The metal structures protected in a station include buried oil or gas pipelines, sewage pipelines, vent pipelines, tank bottoms, equipment foundations and grounding systems, etc. These metal structures with poor coating or even without coating, such as tank bottoms, grounding systems, will consume large quantity of protective current and cause problems of interference and shielding, which brings challenges for the design of regional cathodic protection. In this work, several key technologies were studied on regional cathodic protection, such as the determination and reduction of current requirement, the disposal of shielding and interference problems.

Predicted Potential Distribution of
Underground Pipelines within the Station

Regional CP systems play an important role in ensuring the operational safety of gas & oil stations. The paper concluded that to further improve its performance, the following should be paid more attention. 1. Due to the complexity of buried metal structures within stations, field test methods with temporary anode ground beds and power supply are recommended to determine the current requirement. 2. Numerical simulation is very useful in the design of regional CP systems, based on which the shielded zones can be pre-treated during the design stage. 3. The CP system of transmission pipelines is more susceptible to interference by the CP system of the station. If it cannot be avoided in the design, mitigation methods should be adopted.

This paper presented at NACE 2014 can be obtained from www.nace.org
If you would like further information or to discuss the application, please contact us

Improved Effectiveness Of Direct Assessment Field Surveys Through The Application Of Boundary Element Analysis (BEA) To Simulate Electrical Field Interference Between Collocated Pipelines. Katurah Hansen, Angel R. Kowalski, Shane Finneran, Jason Land. Det Norske Veritas (USA), Inc.

Direct Assessment above ground surveys are often time consuming, laborious, expensive and require operational knowledge of NACE Standard TM0109-2009. The use of boundary element analysis (BEA) software allows for a more comprehensive re-creation of different possible conditions and can provide additional analysis to validate survey results when conditions, such as buried metallic structures adjacent to the pipeline being assessed limit the sensitivity of the survey tools. This combined use approach offers the benefit that a simulation model can be developed that fits well to the actual conditions of the pipeline, with minimal assumptions.

To evaluate the effectiveness of the designed CP System, a boundary element analysis (BEA) was performed to analyze the predicted potential distribution and current density for the natural gas pipeline collocation. The interfering current makes it difficult to accurately calculate these distributions by other methods. Results from the BEA allow for current shielding, over potential hot spots, and other critical areas where the CP is least effective, to be identified.

This paper presented at NACE 2014 can be obtained from www.nace.org

If you would like further information or to discuss the application, please contact us

ICCP System Design on the Hull of an Ice Breaker by Computational Analysis. Min-Jung Lee, Chae-Seon Lim. Samsung Heavy Industries Co., Ltd

Coating damage on the hull of an Arctic vessel
after 2.5 years under Arctic Sea

Impressed current cathodic

protection (ICCP) systems have been employed with coatings to prevent corrosion on the hulls of ice breakers. Many ICCP systems used for commercial vessels are designed based on the designer's experiences rather than by analytical method. The purpose of this paper is to simulate the performance of ICCP systems on hulls under Arctic conditions by a computational analysis based on boundary element methods (BEM) and to deduce an optimized design. For this purpose, an Arctic shuttle tanker that will travel across the Barents Sea was investigated. The coating breakdown factors at the end of the design life were assumed to range from 1% to 5% depending on the ice strengthening areas of the hull. The design optimization process consisted of a series of calculations of the structure potential with several cases of ICCP system arrangements and reference cell target potentials. The effects of these factors were studied under Arctic conditions.

The model predicted the potential distributions on the hull and the results were used to determine the optimized design of the ICCP systems under the service conditions.

This paper presented at NACE 2014 can be obtained from www.nace.org
If you would like further information or to discuss the application, please contact us

The Application Of Computer Modeling To Improve The Integrity Of Ballast

Optimized anode layout showing initial consumption rates

Tanks. Robert Adey, Guy Bishop, John Baynham, CM BEASY Ltd

Generally additional cathodic protection (CP) systems are installed in ballast tanks to provide protection to the areas that may become unprotected by degraded coatings. Because of the complex geometry of the tanks and the presence of pipework, equipment and in some cases ladders and walkways the correct placement of both sacrificial & ICCP anodes is essential to get a good potential distribution that ensures no areas are either under or over protected.

Computer modeling has become widely used in the maritime corrosion industry to predict the performance of CP designs and to ensure adequate protection is provided to the structure over its life. In this paper a case study is presented where computer modeling is used to verify and optimize the design of the corrosion control system of a ballast tank and to predict how it will perform over the service life of the tank. Case studies are presented for both a sacrificial CP system and ICCP design.

This paper presented at NACE 2014 can be obtained from www.nace.org

If you would like further information or to discuss the application, please contact us

CP Design For Offshore Wind Turbine Foundations

An interesting article was published in the September issue of the NACE Materials Performance magazine. The article presents design considerations and some of the challenges a corrosion engineer encounters while designing a cathodic protection (CP) system for offshore wind turbine foundations. The authors were Sameer Ayyar, Jacob Jansson and Ruth Sorenson from COWI A/S Copenhagen, Denmark.

The study was supported by computer modelling where a number of options were evaluated. In the figure shown here the model results for an anode cage attached to a monopile structure at a MP Magazine September 2014 level of -5 to -10m can be seen. The immersed surface of the monopile is bare. Corrosion protection is extended to all the external immersed surfaces and 5m below the mudline.

Project: London Array Offshore Wind Farm. Image source. COWI.

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Training

Training courses can be provided at customers' sites and can be tailored to meet the specific needs of the client.

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