Water Line Corrosion

Introduction

Seal water blades “SS304” which surround the reheating furnace have been inspected by the technical team due to failure happening to those blades. This system was changed in 2016 with new SS304 blades. Effected Blades were showing a combination of deposits & corrosion on the surface of the metal, and it comes in a linear & straight shape.

A sample of that deposit and corrosion product was collected and analyzed in Veolia laboratory to give a clear picture of the nature of that deposit, and corrosion. An XRF spectrometer analysis was carried out, and the results confirmed high CaO, and SO3 compounds in those deposits. In addition to that, Ferric oxide, and Ferric Chloride compositions also existed, and this mainly came as a result of corrosion.

After further investigation done at the site and in our laboratory, we figure out that the failure happened due to mainly two reasons:

• Deposit build up on the water line due to dryness and high temperature conditions at the waterline.
• Under deposit corrosion due to chloride ions and sulphate ions migration under deposit layer in absence of oxygen beneath this layer, this type of corrosion is called waterline corrosion.

Waterline corrosion on seal…