2019 National Days on Corrosion and Protection: Laboratory investigations carried out on a piece of smoke pipe related to superheated water generator body damaged in operation

C. Dellabiancia, L. Rolla, M. Dellabiancia

WATER SIDE CORROSION IN STEAM GENERATORS

Water side corrosion is one of the most important failure phenomena that can affect generators of the type under examination.

From the chemical point of view the waters can react with metals and in particular with Fe present in the steel tubes to the C of the tube bundle so as to form a protective oxide layer, Magnetite, a cortical layer that constitutes a sort of barrier to further reactions.

On the other hand, in order to maintain an adequate integrity of the oxide layer in order to avoid the progressive corrosion of the metal, a continuous and adequate control of the chemistry of the process water is necessary, if not a priority.

In the following document, which we presented as speakers during the conference “National Days on Corrosion and Protection” held in Palermo – from 3 to 5 July 2019 – we report a case study conducted by our laboratory team, highlighting:

1. General information on damage
2. Sample received
3. Performed laboratory investigations (Visual examinations – Macrographic examinations – Thickness surveys – Chemical analysis – Mechanical tests – Microscopic examinations – Electron microscope examinations)
4. Conclusions and Observations

CASE OF STUDY

General information on damage

At a school complex were installed for the preparation of the N ° 03 high energy efficiency pressurized combustion thermal generators with three turns of smoke pipes.

About two years after commissioning in one of the boilers the first passing lesions of some smoke pipes and crater-like corrosion phenomena on other pipes were detected.

READ THE INTEGRAL DOCUMENT HERE

generatore termico combustione pressurizzata del tipo in esame/pressurized combustion heat generator of the type under examination