Accession Number : ADA195672

Title :   Prediction of Tube-Tubesheet Galvanic Corrosion Using Long Term Electrochemical Polarization Data.

Descriptive Note : Research and development rept.,

Corporate Author : DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT

Personal Author(s) : Scully, John R ; Hack, Harvey P

PDF Url : ADA195672

Report Date : Mar 1988

Pagination or Media Count : 46

Abstract : Prediction of the rate of galvanic corrosion by the use of galvanic corrosion rate tables or by techniques based on electrochemical polarization are useful but do not take into account current distribution effects. A common geometric configuration that exists on ships where dissimilar metals are used and where galvanic current distribution is not expected to be uniform is the tube and tubesheet configuration in a condenser or heat exchanger. Higher galvanic current densities are expected on the tube surface close to the tubesheet, with the current falling to insignificant levels at some distance away from the tubesheet. For predicting tube corrosion where the tube is more active than the tubesheet, or for predicting tubesheet corrosion if the reverse is true, the distance of galvanic interaction is most important since it changes the effective anode to cathode ration, which has a significant bearing on the overall corrosion rate of the anode. Keywords: Galvanic corrosion; Marine engineering. (jes)

Descriptors :   *GALVANIC CORROSION, *ELECTROCHEMISTRY, ANODES, CATHODES, CORROSION, DENSITY, DISTRIBUTION, ELECTRIC CURRENT, GEOMETRIC FORMS, HEAT EXCHANGERS, INTERACTIONS, MARINE ENGINEERING, METALS, POLARIZATION, RANGE(DISTANCE), RATES, RATIONS, SURFACES, TUBES

Subject Categories : Properties of Metals and Alloys
      Marine Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE