Explanation of tuberculation scales formation in steel and iron pipes using the theory of wave motion of a liquid

Alexey Andrianov,Evgeny Orlov,L Slătineanu,A.M Mihalache,C.E Panait,M Boca,R Ibanescu,M Coteata,M.I Ripanu,V Merticaru,G Nagit,O Dodun

doi:10.1051/matecconf/201817804002

Abstract

Electrochemical corrosion of steel and iron pipes in water supply systems is a common problem that causes financial losses to operating companies and deteriorates water quality. A comprehensive study of corrosion deposits formation mechanism is necessary for a better understanding of the processes occurring in pipelines and for scientific justification of monitoring and predicting techniques. The influence of various factors (in particular the water flow velocity) on the formation, growth, and spatial distribution of tuberculation scales on the inner surface of pipes is considered. To study the effect of flow velocity, simple serial tests were carried out on segments of a steel non-galvanized pipe in static and dynamic conditions. The difference in the formation of anode and cathode sections in two dynamic modes is recognized. The first stage of tubercle formation is observed. It was assumed that in pipes with turbulent water flow near metal surface, waves forming tubercles are appeared, and the distribution of the tubercles is depend on water flow velocity.

Highlights

Steel and cast iron pipes are widely used in external and internal water supply systems
Operators stay focused on the problem of metal pipe corrosion, since it leads to financial losses and degradation of tap water quality
The majority of works dedicated to corrosion study test coupons or samples of pipes removed from an operating water supply system

Summary

Introduction

Steel and cast iron pipes are widely used in external and internal water supply systems. In our previous paper [10], we made an assumption about the impact of water motion on tubercle formation In this case, their active growth starts when oxygen concentrations under the base sediment drops below 1 mg/l and the dense layer is generated by cathodic reduction of the loose γ-FeOOH sediment to magnetite Fe3O4 [11]. When iron hydroxide solution, which fills the cavity after a bubble is removed, becomes supersaturated, the cavity undergoes mass crystallization resulting in formation of a spherulitic skin consisting mainly of goethite and lepidocrocite This sediment forms a laminated base for a tubercle. The hypothesis is based on the assumption that growth and formation of the tubercle base was considerably influenced by water velocity in pipes

Materials and methods

Results and discussion

Conclusions