Pipeline architecture consists in several stations in series configuration; hence the unavailability of one station impacts the availability of the whole pipeline. This lead to the need of optimizing the availability of each station in terms of configuration and number of units required in order to be able of satisfying the demand at any time. The loss of production cost in gas supply application is very high.
Aero-derivatives gas Turbines are typically used as drivers in pipeline applications since they maximize train efficiency, minimizing gas consumption.
PGT25+ aero-derivative Gas Turbines are among the most popular units applied in pipeline services. They merge demonstrated reliability performances together with a very limited outage duration impact that leads to very high Availability. Outage duration is optimized through modular replacement of both GG and HSPT that is facilitated by light weight of the machine.
A Reliability Block Diagram has been built with the aim to optimize the Pipeline PGT25+ Gas Generator scheduled maintenance. Each block represents a Gas Generator while each station is realized taking into account the actual k-out-of-N configuration of each station units.
Once the model has been created, a sensitivity analysis has been performed in order to estimate the impact of the Gas Generator cycle time (Gas Generator refurbishment time),that is what if larger or shorter than the baseline 6 months. Further, even a sensitivity study has been carried on to estimate the impact of the number of available spare parts on the delay that some units will suffer due to un-sufficient number of GG spare with consequent higher risk.