4　Raw Material

4.1　The Horizontal Extrusion Process

4.1.1　The cast billet，rolled billet and forged billet with round section may be used as raw material for horizontal extrusion.

4.1.2　The chemical composition，microstructure and the like of the billets shall comply with those specified in the relevant current national standards related to steel pipe products.

4.1.3　There shall be no defects like lap，line defect，crack and shrinkage cavity on the surface and inside of the billet.

4.1.4　The outline dimensions shall meet the requirement of extrusion process.