The effect of chlorides on metal corrosion has been known for a long time, and continues to be extensively studied in order to adopt the best practices with regard to mitigation. The dominant type of corrosion in the presence of chlorides is pitting corrosion.

Bromides on the other hand have not been extensively studied, and – after being proposed for a well-start up application for flexible pipes in offshore Trinidad – a general literature review was conducted to assess their compatibility against 2205 duplex stainless steel.

In this review, a general understanding of pitting corrosion is presented, along with some mechanisms found in the literature. Additionally, the influence of inclusions, and alloying elements is highlighted, as well as the particular section on the effect of different halides (bromide vs chlorides). It is commonly understood that chlorides are more severe than bromides, however the literature survey showed that this is not applicable in all cases.

A 5-day screening test was devised to compare the effect of the two halides individually, and a mixed solution containing both of chloride (CaCl2) and bromide (NaBr). This paper will cover how this investigation was undertaken and present its findings, including how the combination of chlorides and bromides can also alter the aggressiveness of the environment.