Optimising substation refurbishment through reuse and modification of existing steel support structures: A case study at a 132 kV substation

African utility network, with specific focus on switchgear support steel.

In many refurbishment projects, support steel is replaced whenever the footprint of replacement equipment does not align with existing mounting points. This typically drives new fabrication, lead time, installation effort, and additional site works. The approach described here retains existing steelwork where it is structurally adequate and introduces only the modifications required for fitment and compliance.

The scope commenced with an on-site inventory and as-built verification of the relevant support structures, followed by condition screening and coating assessments. Structural verification was then undertaken using load models representative of the replacement equipment and yard operating conditions, in accordance with applicable SANS and IEC requirements. Fitment differences were addressed primarily through re-drilling and the introduction of small interface components. No member strengthening was required.

1 For the switchgear scope assessed, the conventional baseline requirement for new steel was 41.18 t. The reuse-first strategy reduced new procurement to 3.10 t through the reuse of 100% of the circuit breaker and earth switch steelwork, and 85% of the isolator steelwork. The remaining isolator requirement was accommodated using supplementary brackets; 15% was sourced from decommissioned steel available on site and 10% was procured new. This approach delivered a substantial reduction in new steel demand, with corresponding benefits in cost and embodied carbon.