Description: Broken pipes and scrap being weighed (before re-smelting ?, or weighing of wastage ?). Note the magnetic crane in the background lifting a pile of metal. The Sand Spun Plant made pipes using a centrifugal method. Known as sand spun or mono cast, molten iron was poured into a sand lined mould which would then be rotated at high speeds. Besides eliminating the need for a central sand core, this method also produced pipes of greater durability and with even wall thickness'.