Polatrak Deep C Meter 300 AD, Operation Manual, Page: 10 / 16

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© 2015 Deepwater Corrosion Services Inc. Specifications subject to change without notice
Deep C Meter 300 AD™ operation manual
10
SMB-001 Deep C Meter 300 AD Manual
8.1.19 Using a 7/16” (or 10mm) wrench, ensure that the contact tip is tight on the nose cone.
8.1.20 Ensure that the tip is sharp.
9. Taking CP potential readings
9.1. Stab the contact probe onto the point on the structure where the reading is required; when a
good contact is made, the Deep C Meter 300 AD™ will show a steady reading.
CAUTIONS
• Avoid stabbing painted or coated surfaces; whenever possible, try to take readings on bare steel or
on spots specially designated for CP measurement. CP stab points are typically labeled with “CP”.
• Anodes can be stabbed if necessary; however, it is always best to stab the anode band where
possible, as it is typically grounded to the structure.
• Avoid trying to stab through heavy, hard marine growth if possible.
• The probe unit should be kept out of the mud to prevent contamination of the electrodes.
• If the readings are not steady or do not match the criteria in Table 3 below, the most likely cause
is a high-resistance contact. DO NOT RECORD THESE NUMBERS. Continue to stab until readings
stabilize and follow the recommended action. See troubleshooting section 13 if problems persist.
• NEVER immerse the system with any connectors un-mated unless the dummy plugs are installed.
10. Data interpretation
10.1 For carbon steel structures in seawater, the readings obtained should be within the ranges
specified in Table 3. Exceptions may occur if the probe is stabbed onto an isolated section of a
corrosion-resistant alloy such as stainless steel, copper or nickel. In these cases, Table 3 no longer
applies and readings less negative than indicated in the table may be noted. If this is the case, en-
sure that the readings are steady and the electrodes maintain the same potential difference between
each other during the last calibration check.
Table 3: Normal cathodic protection ranges for bare carbon steel in seawater
Range (mV) Interpretation Action
-500 or more positive Error
Remake contact & verify
Measure two other points around the
component
Abort & refer to troubleshooting section
-501 to -649 Isolated from cathodic protection
Remake contact & verify
Record data
-650 to -799 Not cathodically protected
-800 to -849 Marginal cathodic protection
-850 to -1049 Cathodically protected
Record data
-1050 to -1149 Anode potential
-1150 or more negative Error
Remake contact & verify
Measure two other points around the
component
Abort & refer to troubleshooting section
10.2 Removal from ROV
10.2.1 When equipment is removed from the ROV, wash thoroughly with fresh water and allow to
dry. Soak the ROV-II and EFG probe units in fresh water for at least one hour. Replace lens cover
on Deep C Meter 300 AD™ and place it in the protective case provided.