2.6
LEAD WIRE CONNECTIONS
Lead wire to structure connections shall be by exothermic welding process.
Weld charges made specifically for use on cast iron shall be used on cast
iron pipe. A backfill shield filled with a pipeline mastic sealant or
material compatible with the coating shall be placed over the weld
connection and shall cover the exposed metal adequately.
PART 3
EXECUTION
3.1
CRITERIA OF PROTECTION
Acceptance criteria for determining the adequacy of protection on a buried
[pipe] [tank] shall be in accordance with [NACE RP0169,] [and] [NACE RP0193,]
and as specified below.
3.1.1
Iron and Steel
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NOTE: If the second method is used, the requirement
for obtaining measurements over 95 percent of the
entire metallic area is required as in the first
method. Verification of the 100 millivolts decay of
polarization should be achieved at points over 95
percent of the entire metallic area.
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The following method a. shall be used for testing cathodic protection
voltages. If more than one method is required, method b. shall be used:
a.
A negative voltage of at least minus 850 millivolts as measured
between the [pipe] [tank] [specified underground component] and a
saturated copper-copper sulphate reference electrode contacting
the (electrolyte) earth directly over the [pipe] [tank] [specified
underground component]. Determination of this voltage shall be
made with the cathodic protection system in operation. Voltage
drops shall be considered for valid interpretation of this voltage
measurement. A minimum of minus 850 millivolts "instant off"
potential between the [structure] [pipe] [tank] [specified
underground component] being tested and the reference cell shall
be achieved over 95 percent of the area of the structure.
Adequate number of measurements shall be obtained over the entire
structure, pipe, tank, or other metallic component to verify and
record achievement of minus 850 millivolts "instant off". This
potential shall be obtained over 95 percent of the total metallic
area without the "instant off" potential exceeding 1200 millivolts.
b.
A minimum polarization voltage shift of 100 millivolts as measured
between the [pipe] [tank] and a saturated copper-copper sulphate
reference electrode contacting the earth directly over the [pipe]
[tank]. This polarization voltage shift shall be determined by
interrupting the protective current and measuring the polarization
decay. When the protective current is interrupted, an immediate
voltage shift will occur. The voltage reading, after the
immediate shift, shall be used as the base reading from which to
measure polarization decay. Measurements achieving 100 millivolts
shall be made over 95 percent of the metallic surface.
SECTION 13112A
Page 27
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