Estimating Flare Gas Heat Radiation Temperature and its Effect on FPSO Hull Corrosion in the Gulf of Guinea.

Breakdown of Floating Production, Storage, and Offloading systems (FPSOs) due to corrosion has been a major cause of downtime in FPSO operating in various regions. A major cause of corrosion in the FPSO is the radiation from jet flame of gas flare stack installed on FPSO. Although gas flaring on the FPSO is very resourceful in the disposal of hydrocarbon gas resulting from a variety of process conditions it has become an “Achilles Heel”. This study therefore sort to determine heat radiation from the gas flare stack in the Gulf Guinea on an FPSO and investigate the impact of the radiation on the Hull of the FPSO and other structures on it made of mild steel. The thermal radiation was simulated using PHAST – DNV software considering the production host peak period and offpeak period. The former period constitutes the harsh case the latter represents the mild case. A manual computation and conversion of the heat radiation from the FPSO was done and a temperature range of T’0= 70℃ and T’E = 96.2℃ for mild case condition and T’O = 73.63℃ and T’E = 118.4℃ for worse case condition was determined. Gravimetric measurement was used to determine the weight loss from which the corrosion rate and metal loss were calculated. The influence of the resulting temperature as the major metocean condition of interest was determined and its synergistic interaction with other metocean conditions – pH and Salinity were examined. The results indicate that radiation from gas flare stack impacts on the corrosion rate and metal loss of mild steel used as a Hull for an FPSO in the Gulf of Guinea.