Corrosion performance in sulphuric acid
Mass Loss
A mass loss corrosion test is submitted prior to shipping as part of the compliance test of Aushex internal engineering standard: AUS01-SuperHex-Rev1, Section 5.2.2 This is a simple and straightforward corrosion test that can be reproduced at any location as long as general guidance is kept.
The conditions are: Uninhibited sulphuric acid 6% v/v, 60 °C constant temperature, 15 Hours exposure, and 1 m/sec agitation.
Manufacturing End Product
Cut sections of the final tube size are exposed under the above conditions. The final and standard size is: 38.1 mm OD and 2.4 mm WT
Electrochemistry Measurements
Two electrochemistry techniques (LPR and EIS) highlight the superior quality of the Superhex compared to the STD ASTM 179.
High corrosion resistance and low corrosion rate correspond to the Superhex compared with low corrosion resistance and high corrosion rate for the STD ASTM 179.
Nyquist Plot
Nyquist plot is perhaps the best graphical display of the corrosion behaviour of Superhex compared to other materials used in the Bayer process.
The diameter of the semicircle indicates the magnitude of their corrosion resistance.