Kings Cross Triplets Gasholder Restoration

This project saw the restoration of the Grade II Listed Triplets Gas Holders, constructed from a combination of cast and wrought iron. The combined structures contained 123 cast iron columns, each over 10m long and weighing, on average, 10 tonnes each. This and all the connecting lattice works presented a large-scale restoration and painting project. The works were carried out off-site at our in-house workshop.

All components were placed in a strictly controlled area with specifically built racking to ensure historic component protection and maximum efficiency of space. Each component was subject to an initial pre-blast where historic lead-based paint was removed to expose the base material.

All structural cast columns required major structural repair works. In one case, a full column repair sleeve was applied to re-build the columns structural integrity. English Heritage did not opt for a replacement column but wished to preserve the historic building fabric.

A large majority of the wrought iron lattice beams had deteriorated due to a lack of maintenance over the years. Due to corrosion, the endplates were replaced along with repairs to the interconnecting lattice beam outer angle structure. All repair types were of a mechanically fixed over-plate design as instructed by the engineering team.

Following repair of each component, the goods were blast cleaned prior to applying the corrosion protection system. The system was a three-part coating system made up of a primer basecoat zinc phosphate primer, a midcoat of micaceous iron oxide and a topcoat of high-performance acrylic urethane gloss finish. All paints, along with wet and dry film thicknesses, were specified by the Client team coatings advisors and paint manufacturers.

On completion of the coating system application and curing period, the components were transported back to the yard-based racking systems for storage until requested for delivery to site by the client team. The storage racking at this stage was wrapped using ‘Envirowrap’ to protect the batch of components from weathering for up to 18 months.

The components processed were up to 8 tonnes in weight and up to 10m in length, each component required strategic handling and movements to both protect the workforce and the heritage material. Columns required lifting cradles and strict 7-point lifts for structural integrity protection. All lifting, handling and movements of products were controlled via training and strict method statements and risk assessments.

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17 Addiscombe Road

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