Hydrogen network retrofit via flexibility analysis: The steady-state flexibility index

•A systematic approach has been presented to retrofit design of hydrogen distribution network.•The hydrogen production of utilities and hydrogen consumption of resources have been reduced.•The hydrogen network operation has been improved by the optimal solution of the flexibility index model.•The total annual cost of the refinery hydrogen network has been reduced. A systematic approach is presented to retrofit design of a hydrogen distribution network. A methodology is based on the steady-state flexibility index (FIs) for optimizing network and enhancing the efficiency of purifiers. The main object of this technique is to investigate hydrogen network flexibility under severe operation uncertainty and to reduce streams to purifiers by consideration inlet feed purity of purifiers. The presented approach is applied to the hydrogen network of a real installation.