5.2　The Vertical Extrusion Process

5.2.1　The vertical extrusion process shall comprise raw-material preparation，extrusion forming，pipe finishing，heat treatment and product inspection.

5.2.2　Hot-transfer and hot-charging technology should be used for raw material of the extrusion process.

5.2.3　Raw-material preparation shall include surface cleaning and riser-head cutting.

5.2.4　Extrusion forming shall comprise reheating，descaling，lubrication for piercing，upsetting &piercing，descaling，lubrication for extrusion，extruding and cooling.Other procedures may be added depending on product variety.

5.2.5　Pipe finishing shall comprise inside-and outside-surface shot blasting，straightening，end-face machining，inside-and outside-surface processing，weighing，spraying marking，printing and packing.Other procedures may be added depending on product variety.

5.2.6　Annealing，normalizing，normalizing & tempering，solution treatment and the like can be used for heat treatment.

5.2.7　Product inspection shall include non destructive test（NDT），inside and outside surface checking and outline dimension inspection.Other procedures may be added depending on product variety.