Some of a cast iron pipes have a tendency to corrode and crack over time, and this process often starts in places we have little or no access to. It is a defect caused by inadequate annealing heat treatment of the cast iron pipe during the manufacturing process (repeated heating and cooling).
Manufacturing Process of Cast Iron Castings The making of cast iron begins with a combination of raw materials. Iron is rarely found in its pure form. Only meteorites contain pure iron. The iron in use for centuries is found in the combination of iron and other elements. These combinations are known as iron oxides.
Centrifugal casting of gray iron in watercooled metal molds is widely used by the cast iron pipe industry as well as for some other applications. With sand or other refractory lining of the metal molds, the process is used for making large cylinder liners.
This process enables the feeding with low quality scrap metal, which is particularly important in times of scarcity. Spinning process. Ladles of melted iron are taken from the forehearth and supply the pouring boots, reservoirs at the head of the spinning machines, which contain enough to make several pipes depending on the diameters to be spun.