Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.
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The MP Blog Experiences and opinions from readers on corrosion issues protected and could be affected by your CP system? • Have you already designed the groundbed, and do you know its resistance, or do you need the The excerpts are selected for their potential groundbed design? interest to a large number of NACE All of these variables can affect the members. They are edited for clarity and decision, but as an example, I have inlength. Authors are kept anonymous for publication. stalled a CP system for three new 24-km Please be advised that the items are FBE-coated pipelines with good quality not peer-reviewed, and opinions and control during the installation, and we suggestions are entirely those of the just needed 0.5 A to protect the pipes over inquirers and respondents. NACE does not guarantee the accuracy of the technical –850 mV vs. copper/copper sulfate (Cu/ solutions discussed. MP welcomes CuSO4) reference electrode. Other times additional responses to these items. They I have needed four rectifers for just 14 km may be edited for clarity. For information on how to subscribe to these of 3-m diameter pipe, because the coatfree list servers, click on the "Corrosion ing was poor. The characteristics of your Central" link and then "Online Corrosion particular pipeline system will determine Community List Servers" on the NACE Web the amount of protection you need. site: www.nace.org. The following are excerpts from the NACE International Corrosion Network (NCN) and NACE Coatings Network. These are e-mail-based discussion groups for corrosion professionals, with more than 3,000 participants. rectifer current output for cathodic protection Q I need clarity on an impressed current cathodic protection (cP) system design. Can a rectifer with a 100-V, 50-A rating adequately supply direct current to protect a 6.2-km, 36-in (914-mm) diameter pipeline with fusion-bonded epoxy (FBE) coating in 5,000 Ω-cm soil for 15 years? A • • • • 10 Here are things you need to consider before deciding on a rectifer size: • Quality of the FBE coating Length of time the pipe is buried Have you done any kind of current demand test for this pipe section? Are you thinking about installing other pipes in the same corridor or the same area? Do you have foreign pipes buried in the area that are not cathodically MATERIALS PERFORMANCE May 2013 plans for building a potentiostat Q A Does anyone have any good, do-it-yourself plans for building a potentiostat? There is an article, "Low-Cost Electronic Devices for Corrosion Measurements," by Baboian and Prew in the July 1993 issue of Materials Performance. It contains a circuit diagram for a potentiostat built around an op-amp. I have built potentiostats based on this circuit and they work very well. Cathodic protection for water pipes Q We are interested in knowing more about impressed current cathodic protection (IccP) for water pipes. Continued on page 12 editorial direCtor, Content development managing editor Gretchen A. Jacobson teChniCal editor John H. Fitzgerald III, FnAce a S S o C i at e e d i t o r Kathy Riggs Larsen e d i t o r i a l a S S i S ta n t Suzanne Moreno ContriBUtor Husna Miskinyar graphiCS e l e C t r o n i C p U B l i S h i n g C o o r d i n at o r Teri J. Gilley graphiCS deSigner e. Michele Sandusky adminiStration naCe exeCUtive direCtor Robert (Bob) H. chalker groUp pUBliSher William Wageneck advertiSing SaleS manager Diane Gross aCCoUnt exeCUtiveS Brian Daley Pam Golias Jody Lovsness Leslie Whiteman a d v e rt i S i n g / B o o K S C o o r d i n at o r Brenda nitz r e g i o n a l a d v e rt i S i n g S a l e S r e p r e S e n tat i v e S The Kingwill co. chicago/cleveland/new York Area– +1 847-537-9196 nAce International contact Information Phone: +1 281-228-6200 Fax: +1 281-228-6300 e-mail: Firstservice@nace.org Web Site: www.nace.org editorial adviSorY Board John p. Broomfeld, FnaCe Broomfeld Consultants raul a. Castillo Consultant irvin Cotton arthur Freedman associates, inc. arthur J. Freedman arthur Freedman associates, inc. orin hollander holland technologies W. Brian holtsbaum dnv russ Kane iCorrosion, llC Kurt lawson mears group, inc. lee machemer Jonas, inc. ernest Klechka Citgo petroleum Corp. norman J. moriber mears group, inc. John S. Smart iii packer engineering l.d. "lou" vincent l.d. "lou" vincent phd llC NACE International, Vol. 52, No. 5