Risk Based Integrity Modeling of Offshore Process Component Piping

This paper discusses on the methodology to develop a risk-based integrity model of offshore process piping (surface flowlines) which degrades due to corrosion. Gas processing plants are highly hazardous which deals with chemicals at extreme conditions such as high temperature and high pressure. These facilities should be going through the right maintenance and inspection from time to time to ensure a safe environment, continuous and fault-free operation. Deterioration of gas facilities gives a major impact on the continuous operation of the facilities. This paper proposes a risk-based integrity modelling methodology to have a fault-free operation for the facility’s piping (also known as surface flowlines). The risk‐based integrity model is to develop the model of offshore surface flowlines’ corrosion mechanism efficiently to obtain an optimum replacement plan. The economic consequences of offshore surface flowlines corrosion mechanism are developed in terms of the cost of failure, inspection and maintenance. The optimal replacement strategy is obtained by combining the collective posterior probability of failure and the corresponding rate of corrosion. Risk-based integrity’s assessments use the structural corrosion data which are modelled using the prior probability information. This prior probability information can be restructured to posterior probability using Bayesian Theorem and ASME B31.3 prediction method with the support of the inspection data of the facility. Posterior probability will then be used to estimate the likelihood of the piping failures in the facility. This can then lead to quantify the possible ageing hazards to the facility and identify the replacement interval of the components to avoid hazards. The consequence will be measured by cost as a function of time. This paper focuses mainly on general corrosion on the surface flowlines (topside pipeline).