This new manufacture technique of a kind of API steel pipe which belongs to straight seam welded steel pipe is being widely accepted around the world. As a matter of fact, the API steel pipe is a kind of welded steel pipe that has no seams. Although the API steel pipe has not many applications like the welded steel pipe, the API steel pipe is mainly used for industry that links to the oil. And its application is increasing because of the increasing of the oil demand.
This kind of manufacture technique controls reasonably the sulfur content of carbon, phosphor as well as the sulfur and adds to a trace of alloying elements at the same time. The manufacture method of this straight seam welded steel pipe( API steel pipe) is that first, carry out pretreatment to the molten iron, and then proceed with smelt, refine, sheet stamping, hot rolling, laminar flow cooling, plate rolling, seam welding as well as test. And in the middle of welding technique, it is better to control the parameters such as welding speed, welding temperature, extrusion amount as well as the angular aperture.
This kind of manufacture technique improve the composition proportion of material that is used for producing API steel pipe and promote the welding technique at the same time. Thus, the API steel pipe has the characteristics of high dimensional accuracy, good welding toughness, good performance of the extrusion as well as easy to control the quality and low cost. At present, the seamless API steel pipe that is used in petroleum industry has the problems of large ovality, uneven wall thickness, not enough damage resistant property. Using this kind of API steel pipe severely influence the service life of the wells. The welded steel pipe and carbon steel pipe are also available. Thus, it is important to produce a kind of manufacture technique that can overcome the shortcoming of current technique.
The detail manufacture technique is as follows. First, carry out the pretreatment of the liquid iron. And then put liquid iron after pretreatment into the revolving furnace to carry out smelting. And add alloying elements in the middle of melting. Next, put liquid steel after smelting in the revolving furnace into the refining furnace again to proceed with smelting. And make the liquid steel after smelting in the refining furnace into the steel feed. And then, turn the steel feed into banding board through blooming, precision rolling and finish rolling with hot rolling mill. And then carry out laminar flow cooling treatment to the banding board after hot rolling. Then wind the banding board after laminar flow cooling treatment into casting pipe with winding machine. Finally, weld the welding seam of the casting pipe after winding with welding machine.
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