A spare part, spare, service part, repair part, or replacement part is an interchangeable part that is kept in an inventory and used for the repair or replacement of failed units. Spare parts are an important feature of logistics engineering and supply chain management, often compresing dedicated spare parts management systems
Capital spares are spare parts wich, although acknowledged to have a long life or small change of failure, wold cause a long shutdown of equipment becaseus it would take a long time to get a replacement for them