Protection and Cleaning of Inner Surfaces of Boiler Components During Manufacturing and Installation

Abstract

Corrosion protection chemicals are sometimes used in protection of inner surfaces of boiler tubes. The purpose is to protect inner surfaces of boiler tubes from corrosion, to make sure the tubes would be in best possible quality when arriving to the installation site. Used corrosion protection chemicals should not harm boiler’s water chemistry, disturb protective oxide layer formation, or cause additional work at the commissioning site. Boiler components are transported from manu facturing workshops located in different countries of the world and stored in alternating environ ments. There can also be variation in transportation distances and storage times between differ ent components in the same boiler.

This thesis studied how the inner surfaces of boiler tubes should be protected and if the cor rosion protection chemicals can be harmful for the boiler tubes. During this work the different corrosion protection chemicals and their effectiveness were evaluated in different environments. It was also studied that how the corrosion protection chemicals affect to the oxide layer formation. The field study with three parts helped to answer the research questions.

First part of field study included comparison of most typically used corrosion protection chem icals. Surface quality of samples were compared to each other and to reference samples. In sec ond part the inhibitors and their affect to the oxide layer formation was investigated. The third part included studying the corrosion protection properties of silica gel.

Testing methods of the field study were selected to answer as well as possible to the research questions. After the inhibitor study of corrosion protection chemicals, the surface quality of sample tubes was compared with each others and with the reference tube. Answers based on the test results are summarized in part “conclusions” of this work.