LESSON 15
INTERNAL CORROSION
Critical Tasks: 01-5103.30-2123
03-5103.00-0078
OVERVIEW
LESSON DESCRIPTION:
In this lesson, we will discuss how corrosion occurs in the storage and handling system, as well as methods to
control it.
TERMINAL LEARNING OBJECTIVE:
ACTION:
Identify internal corrosion causes/effects and methods of corrosion control. Calculate
and interpret the "C" factor for a section of pipeline.
CONDITIONS:
Using the corresponding references and this lesson plan.
STANDARDS:
In accordance with the corresponding lesson plan and FM 10-67-1.
REFERENCES:
FM 10-67-1 and 7 MIL-HDBK-200G
INTRODUCTION
Until bulk petroleum products are consumed they must be handled many times. The buildup of internal corrosion
in a pipeline results in a decrease in throughput, increased maintenance, and contamination of the products moved
through the pipeline system.
1.
Causes of Internal Corrosion.
a. Water (an electrolyte) is in the fuel and settles out during changes of temperature. This water settles
into low points along the pipeline where it contributes to corrosion of the pipe inner surface.
b. Oxygen is present and when combined with water and paraffin (a waxy substance obtained from
petroleum) that are present in the fuel, also contributes to corrosion.
c. Mill scale (abrasives) is a surface oxide film. The scale is not a metal but is electrically conductive
whose potential is more noble the metal. This means that where breaks in the mill scale occur corrosion will
happen. (The metal is the anode, and the mill scale is the cathode.)
d. The combination of the elements (water, oxygen, abrasives, and heat from friction) in the pipeline as
the fuel is moved in the pipeline speeds up the corrosion process.
15-1
QM5200
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