The significance of a seam depends on the depth of the seam and the end use of the cast product. For example, seams often occur on convex surfaces of cast products. If the seam occurs on the exterior surface of a non pressurized drain pipe does it matter? It depends on the depth and cause of the seam, which can only be determined by metallurgical analysis. If you really wish to get deep into the different types of cast iron, how they are processed and their applications, click here.