19 NACE INTERNATIONAL: VOL. 56, NO. 3 MATERIALS PERFORMANCE MARCH 2017
Information on corrosion control and prevention
CIS work on this pipe could show a coating
defect due to voltage changes over the
ground. Photo by Charlie Hernandez,
Chapman Engineering.
current f low," Chapman explains. "A ll it
takes is one foreign current input to jump
onto one of these pipes, and it can give
you widely varying readings."
NACE SP0207-2007
2
is the standard
that describes requirements and recom-
mendations for performing a CIS. It says
that if the goal of a CIS is to evaluate the
level of protection of a segment of pipe-
line, then the entire length of the segment
should be surveyed.
When studied in both 2010 and 2014,
the CIS performed by two separate CP
companies were performed using only
one current-interrupted pass on the cen-
ter pipeline, and without synchronized
current interruption at the locations
where all three pipes were bonded
together. Chapman notes that the prior
work did not properly follow the NACE
standard for CIS performance, adding
that the operator did not have the in-
house knowledge at the time to catch the
mistake.
"This is not proper CIS work," says
Chapman, whose company did CIS work
on all three lines independently in 2015.
"It is an attempt to average three pipes
together, not do an individual interrupted
pass on each pipe. The conductive bonds
have to be specif ically managed with cur-
rent interruption, just as each rectif ier
must be."
"When the pipelines are bonded
together at multiple points, you have to
do current interruption at the bond
points as well as at each rectif ier," Chap-
man explains, noting that the pipelines'
presence in the heart of a shale area
makes them even more susceptible to for-
eign current interference, given the sur-
rounding infrastructure. "That way,
you're getting management of all the cur-
rent involved on all three pipelines, and
every cycle when the current is inter-
Continued on page 20
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