Seamless steel pipe is made of a whole piece of metal, and there are no seams on its surface. It has a hollow section and is widely used as a pipeline for conveying fluids. Compared with solid steels such as round steel, steel pipe has the same bending and torsional strength, lighter weight, and is an economic section steel. It is widely used in manufacturing structural and mechanical parts, in order to improve material utilization, simplify the manufacturing process, and save material and processing time.
Advantages of Seamless Steel pipe
1. Seamless steel tube is lighter under the same strength.
2. Seamless steel pipe without weld seam can withstand greater pressure.
3. Seamless steel tube has high pressure resistance, good toughness, long section and few joints.
4. Seamless steel pipes have hollow sections, which are widely used as pipelines for conveying fluids, such as oil, natural gas, gas, water and some solid materials.
5. Compared with solid steels such as round steel, steel pipe is lighter in weight when its bending and torsional strength is the same. It is an economic section steel and widely used in manufacturing structural and mechanical parts.
Production Procedure of API 5L Seamless Steel Pipe
1. Hot-rolled seamless steel tube
The delivery status of hot-rolled seamless steel pipe is generally hot-rolled after heat treatment. Hot-rolled seamless steel pipe after quality inspection must be strictly selected by the staff by hand. After quality inspection, surface oiling should be carried out, followed by several cold-drawing experiments. After hot-rolling treatment, perforation experiments should be carried out. If the perforation enlargement is too large, straightening and rectification should be carried out. After straightening, the conveyor is transferred to the flaw detector for flaw detection experiment. Finally, the label is affixed, the specifications are arranged and placed in the warehouse. Specific processes are as follows: billet preparation and inspection billet heating piercing rolling pipe reheating sizing heat treatment finished pipe straightening finishing inspection storage
2. Cold-rolled (drawn) seamless steel tube
The general production process of seamless steel tube can be divided into cold drawing and hot rolling. The cold-rolled seamless steel tube billet must be rolled three rolls in succession. After extrusion, sizing test should be carried out. If the surface does not respond to cracks, the tube should be cut by cutting machine, and the billet with a growth of about one meter should be cut. Then enter the annealing process, annealing with acid liquid pickling, pickling should pay attention to whether there is a large number of bubbles on the surface, if there is a large number of bubbles, indicating that the quality of steel pipe can not meet the response standard. The appearance of cold-rolled seamless steel tube is shorter than hot-rolled seamless steel tube. The wall thickness of cold-rolled seamless steel tube is generally smaller than that of hot-rolled seamless steel tube, but the surface looks brighter than that of thick-walled seamless steel tube. The surface is not too rough, and the caliber is not too much burr. The specific process is as follows: billet preparation pickling and lubrication cold rolling (drawing) heat treatment straightening finishing inspection.
Quality Requirements for Seamless Steel Tubes
1. Chemical composition of steel:
The chemical composition of steel is one of the most important factors affecting the performance of seamless steel tube, and it is also the main basis for formulating rolling process parameters and heat treatment process parameters of steel tube.
A. Alloy elements: intentionally added, according to use
B. Residual elements: steelmaking with proper control
C. Harmful elements: strictly controlled (As, Sn, Sb, Bi, Pb), gas (N, H, O)
External refining or electroslag remelting: Improve the uniformity of chemical composition and purity of steel, reduce non-metallic inclusions in billet and improve its distribution.
2. Geometric Dimension Accuracy and Profile of Steel Pipe
A. The accuracy of outer diameter of steel pipe depends on the method of sizing (reducing) diameter, the operation of equipment and the technological system, etc.
B. Precision of steel tube wall thickness: related to heating quality of billet, process design parameters and adjustment parameters of each deformation process, tool quality and lubrication quality, etc.
C. Ellipticity of steel pipe: indicating the degree of non-circularity of steel pipe.
D. Pipe Length: Normal Length, Fixed Length, Permissible Deviation of Length
E. Bending degree of steel pipe: indicating the bending degree of steel pipe: the bending degree of the length of steel pipe per meter, the bending degree of the full length of steel pipe
F. End-face shear of steel pipe: indicating the degree of inclination between end-face of steel pipe and cross-section of steel pipe
G. Groove angle and blunt edge of steel pipe end face
