This paper presents a real case illustrating a challenge where an offshore gas operator observed severe bottom of line corrosion associated with presence of mercury. The uninhibited corrosion rate exceeded 5 mm/yr with the total concentration of mercury present being around 60-100 ppm. Several corrosion inhibitor formulations were reviewed, studied for thermal stability and compatibility with produced brine. After passing no HARMS testing, a specially formulated corrosion inhibitor was evaluated for performance in the high-pressure rotating cage cylinder electrode (HPRCE) under field’s simulated sour and sweet conditions in the presence of mercury. Furthermore, successful inhibition performance across weld electrodes representing pipe material was also reported. This corrosion inhibitor was then field deployed with great performance. The presence of mercury and the range of operating conditions meant that effective chemical dose rates had to be field optimized to effectively control the localized corrosion. Corrosion rates were also monitored via high sensitivity ER probe and are presented in this work.