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Source: "Cathodic Protection", by John Morgan, 2nd edition, 1987
Quote: "3.4.6 Groundbed to Structure Distance.............Suppose a long pipeline is protected and at the mid-point between groundbeds the anode to pipe distance is 5 miles while the pipe approaches within 50 yds of the groundbed at its nearest point. The nearness, or rather the remoteness, of the groundbed may be estimated by considering the voltage drop that would occur in the vicinity of the cathode were this structure not present and the groundbed output was flowing to an infinite cathode. At a point 50 yards from such a 20 amp groundbed in 2,000 ohm cm soil the potential of the ground to infinity would be
so that a pipeline that was laid to run within 50 yards of that groundbed could expect a considerable cathodic swing caused by the positive swing of the earth near the groundbed. If the pipe to groundbed distance had been 200 yds then the positive swing of the ground relative to an infinite cathode would be
Errors: In both equations above, the unit for resistivity "p" is "Ohm.cm"; current "i", amp; distance "d", "yards". These values are directly plugged into the two equations without unit conversion.
Corrections: The unit for distance "d" must be converted into "cm" before it is plugged into the equations. The correct calculations are shown below:
For 50 yards, V=(2000 Ohm.cm x 20 Amp)/(2x3.14x4572cm)=1.39 V
For 200 yards, V=(2000 Ohm.cm x 20 Amp)/(2x3.14x18288)=0.35 V
Source: "Corrosion Prevention by Protective Coatings", 2nd edition, p322
Quote: "Calcareous Deposits Some coatings seem to be permeable to electrons. In this case, the electrons pass through the organic coating and are neutralized on the surface of the coating. When this occurs, the calcareous deposit can buildup on the exterior of the coating."
Errors: Electrons can only survive in vacuum, or in metallic or electronic conductors. Electrons can NOT pass through a non-conductive organic coating. The formation of calcareous deposit is a chemical reaction that does not involve the electron-transfer at all.
Corrections: Discard any of the repeated mention throughout the book that electrons can pass through the non-conductive organic coatings.
Source: "Corrosion of Steel in Concrete - Understanding, Investigation and Repair", by John P Broomfield, 2nd edition, 2007, p236
Quote: "9.5 The Clear/Stratfull empirical calculation Stratfull developed an empirical equation to determine the time to first distress of reinforced concrete in sea water with a know, constant chloride content. Clear modified this to be used for atmospherically exposed structures.
Errors: The respective units for "t" and "Z" in Equation (9.4) are not defined and the equation is wrong.
Corrections: The correct equation should be:
where the units for d, t and Z are inches, years and %wt.
Source: "TBT-Free anti-fouling coatings in 2003 for better or for worse?", Corrosion Management, Nov/Dec 2002, p22
Quote: "Figure 2 shows the leaching rate graph for a typical TBT-free SPC system compared to that of a rosin-based CDP system. The initial leaching rate of the SPC is much lower than that of the CDP system......"
Errors: Figure 2 actually shows otherwise.
Corrections: The legend for SPC and CDP in Fig.2 should be swapped.