The objectives and the context of the major maintenance work carried out on Cockerill Sambre's BF B and 6 are presented. After preparation and dismantling operations, the hearth of BF B was cleaned and relined. Simultaneously, the stock was partly equipped with copper staves. Good planning and coordination allowed the work to be executed in safety, within the schedule and with the required quality. The same principles have been applied for the repair of BF 6.