1. Ductile iron pipe is prone to folding. Folding is a variety of broken lines formed on the surface of ductile iron pipes, and this defect often runs through the longitudinal side of the entire product.
2. The appearance of inferior ductile iron pipes is often pocked. The pitted surface is an irregular uneven defect on the surface of nodular cast iron pipe caused by serious groove wear. Due to the poor quality ductile iron pipe manufacturers to pursue profits, there are often excessive groove rolling.
3. The surface of inferior ductile iron pipe is prone to scarring.
4. The surface of inferior material is easy to crack, because its billet is adobe, adobe porosity, adobe in the process of cooling due to the role of thermal stress, crack, after rolling there are cracks.
5. Poor quality ductile iron pipe is easy to scratch, the reason is that poor quality material manufacturers have simple equipment, easy to produce burrs, scratch the surface of ductile iron pipe. Deep scratching reduces the strength of ductile iron pipes.
6. The inferior ductile iron pipe has no metallic luster and is light red or similar to the color of pig iron. If you do not know how to buy in the procurement, use these six points, you will not buy poor quality spherical ink tubes.
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