JANUARY 31 2003
INSPECTION PROCEDURES AND CRITERIA
INTRODUCTION. This chapter includes criteria and inspection actions that,
when used either separately or in combination, will indicate whether adequate cathodic
protection of a metallic piping system has been achieved (see also paragraphs 3-1 and
Methods. The effectiveness of cathodic protection or other corrosion control
measures can be affirmed by visual observation, measurements of pipe wall thickness,
or by use of internal inspection devices. Because such methods sometimes are not
practical, meeting any criterion or combination of criteria in this chapter is evidence that
adequate cathodic protection has been achieved. When excavations are made for any
purpose, the pipe should be inspected for evidence of corrosion and/or coating
condition. Apply sound engineering practices to determine the methods and frequency
of testing required to satisfy these criteria.
The criteria in this chapter have been developed through laboratory
experiments and/or verified by evaluating data obtained from successfully operated
cathodic protection systems. Situations may exist where a single criterion for evaluating
the effectiveness of cathodic protection may not be satisfactory for all conditions. Often
a combination of criteria is needed for a single structure.
Corrosion leak history is valuable in assessing the effectiveness of cathodic
protection. Corrosion leak history by itself, however, must not be used to determine
whether adequate levels of cathodic protection have been achieved unless it is
impractical to make electrical surveys.
APPLICABILITY. This recommended practice is intended to serve as a
guide for establishing minimum requirements for control of corrosion on the following
New piping systems. Corrosion control by coating supplemented with
cathodic protection, or by some other proven method, should be provided
in the initial design and maintained during the service life of the piping
system, unless investigations indicate that corrosion control is not
required. Consideration should be given to the construction of pipelines in
a manner that facilitates the use of in-line inspection tools.
Existing coated piping systems. Cathodic protection should be provided
and maintained, unless investigations indicate that cathodic protection is