Corrosion Behavior of Pipeline Carbon Steel under Different Iron Oxide Deposits in the District Heating System

Yong-Sang Kim,Jung-Gu Kim

doi:10.3390/met7050182

Abstract

The corrosion behavior of pipeline steel covered by iron oxides (α-FeOOH; Fe3O4 and Fe2O3) was investigated in simulated district heating water. In potentiodynamic polarization tests; the corrosion rate of pipeline steel is increased under the iron oxide but the increaseing rate is different due to the differnet chemical reactions of the covered iron oxides. Pitting corrosion was only observed on the α-FeOOH-covered specimen; which is caused by the crevice corrosion under the α-FeOOH. From Mott-Schottky and X-ray diffraction results; the surface reaction and oxide layer were dependent on the kind of iron oxides. The iron oxides deposit increases the failure risk of the pipeline and localized corrosion can be occurred under the α-FeOOH-covered region of the pipeline. Thus, prevention methods for the iron oxide deposit in the district pipeline system such as filtering or periodic chemical cleaning are needed.

Highlights

A district heating (DH) system provides heat for inhabitants of large cities in an economical manner
The potentiodynamic polarization curves indicated a negative shift in the corrosion potential and an increase in the cathodic and anodic reactions on the iron oxide-covered specimens
The negative shift in the corrosion potential in the α-FeOOH and Fe3 O4 -covered specimens means that the increase in the anodic reaction area was due to the surface reaction from the Fe3 O4 and α-FeOOH [42]

Summary

Introduction

A district heating (DH) system provides heat for inhabitants of large cities in an economical manner. Heat from heat and power generating plants and large heat sources is cheaper than heat produced in individual, low-power boiler rooms [1]. There are many merits to DH systems, including increased energy efficiencies, reduced life cycle costs, and elevated control over environmental impacts [2,3]. The high efficiencies of DH systems decrease the emission of combustion products into the atmosphere. Because of these advantages, many countries such as Denmark, Russia, Finland, and Canada are developing DH systems, and the market share is reported to be approximately. A DH system was introduced to Korea in 1987 and applied to various fields

Results

Discussion

Conclusion