Corrosion testing of sa 387 gr. 91 steel

Abstract

Corrosion behaviour of steel Sa 387 Gr. 91 is tested in solutions containing chloride and sulphate anions. These solutions simulate the conditions of marine and industrial atmosphere. The tests are carried out in a slightly acidic and moderately acidic environment. It is shown that the steel corrodes uniformly without pitting or other forms of local dissolution. Corrosion current density is determined by three independent electrochemical techniques (linear polarization resistance, electrochemical impedance spectroscopy and linear sweep voltammetry). Values of corrosion rate are calculated based on values of corrosion current density. Values of corrosion rate obtained by different electrochemical techniques are in a very good agreement. An estimation of the working life of a pressure vessel made of steel Sa 387 Gr. 91 is given from the standpoint of general (uniform) corrosion.