Pipe for conveying abrasive materials such as concrete, apparatus and method for producing said pipe

Method for producing a tube or curved segment of tube for transferring abrasive materials, comprising a curved external tubular element and a curved internal tubular element made of a material having a resistance to wear greater than that of the curved external tubular element and having a cross section such as to cover at least part of the internal surface of the curved external tubular element, wherein the method provides to make said curved external tubular element and said curved internal tubular element separately,

• the method comprising:
• heating said curved external tubular element at least to around its temperature of deformation,
• inserting said curved internal tubular element inside said curved external tubular element after said curved external tubular element is heated,
• closing a mold, and applying a pressure to an external surface of the curved external tubular element against an external surface of the curved internal tubular element, making use of the heated condition of the curved external tubular element to form the curved external tubular element on the exact geometry of the curved internal tubular element, and
• opening the mold and cooling with consequent shrinkage of the curved external tubular element on the curved internal tubular element.