Seamless Steel Pipe Application and Production Process

Seamless steel pipe is made of the whole round steel perforated, there is no weld on the surface of steel pipe, called seamless pipe. According to the production method, seamless steel pipe can be divided into hot-rolled seamless steel pipes, cold-rolled seamless pipes, cold drawn seamless pipe, seamless pipe extrusion, pipe jacking. According to the section shape, seamless steel pipe is divided into round and shaped two kinds, shaped pipe has square, oval, triangle, hexagonal, melon seed shape, star, with a variety of complex shapes. The maximum diameter is 900mm, the minimum diameter is 4mm. According to the use of different, there are thick seamless steel pipe and thin seamless pipe. Seamless steel pipe is mainly used for petroleum geological drilling pipe, petrochemical cracking pipe, boiler pipe, bearing pipe and automobile, tractor, aviation with high-precision structural steel pipe.
Classification of seamless steel pipe:
A steel tube with no seams on the periphery of its cross section. According to the different production methods divided into hot-rolled pipe, cold-rolled tube, cold-drawn pipe, extrusion pipe, pipe jacking, etc., have their own process.
Materials include normal and quality carbon structural steel (Q215-A ~ Q275-A and 10-50 steel), low alloy steel (09MnV, 16Mn etc.), alloy steel, stainless acid-resistant steel and so on.
According to the use divided into general use (for water, gas pipelines and structural components, mechanical parts) and special (for boilers, geological exploration, bearings, acid, etc.) two categories.
Seamless steel pipe uses:
1, the general use of seamless steel pipe from ordinary carbon structural steel, low alloy structural steel or alloy steel rolling, the largest production, mainly used for the transmission of fluid pipeline or structural parts.
2, divided into three categories according to different uses:
A, according to chemical composition and mechanical properties;
B, according to the mechanical properties of supply;
C, according to water pressure test supply. Pipes supplied according to class a and b shall also be subjected to hydrostatic testing if used to withstand liquid pressures.
3, special purpose seamless pipe has boiler seamless pipe, chemical power, geological seamless pipe and petroleum seamless pipe.
Seamless steel pipe with hollow section, a large number of fluids used for the transmission of pipelines, such as oil, natural gas, gas, water and some solid materials pipeline. Compared with solid steel such as round steel, the steel tube is a kind of economic section steel because its bending and torsion strength is the same.
Widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffolding used in building construction, etc. The utility model can improve the material utilization ratio, simplify the manufacturing process, save material and processing time, and has been widely used in steel pipe manufacturing.
Seamless steel pipe production process:
Main production process of hot-rolled seamless steel pipe (△ main inspection process):
Tube blank preparation and inspection → tube blank heating → perforation → tube rolling → tube reheating → sizing → heat treatment → straightening → finishing → inspection → (nondestructive, physical and chemical examination) → storage
Cold rolled (drawn) seamless steel pipe main production processes:
Blank preparation → pickling lubrication → cold rolling (drawing) → heat treatment → straightening → finishing → inspection
The general seamless steel pipe production process can be divided into two kinds of cold drawing and hot rolling, cold rolling seamless pipe production flow is generally more complicated than hot rolling. Tube billet first three rollers rolling, after extrusion to determine the diameter test, if the surface does not respond to cracks after the tube to cut through the cutting machine, cutting growth of about one meter of billet. Then enter the annealing process, annealing to use acidic liquid pickling, pickling should pay attention to whether there is a large number of surface foaming, if there are a lot of foaming produced that the quality of steel pipe can not reach the corresponding standard. The appearance of cold-rolled seamless steel pipe is shorter than hot-rolled seamless pipe, cold-rolled welded seamless pipe wall thickness is generally smaller than hot-rolling seamless steel tube, but the surface looks brighter than thick-walled seamless steel tubes, the surface does not have too much rough, caliber is not too much burr.
Hot rolled seamless steel pipe delivery state is generally hot rolled state after heat treatment for delivery. Hot rolled seamless steel pipe after quality inspection to go through the staff of strict manual selection, After the quality inspection to the surface oiling, and then followed by several cold drawing experiments, hot rolling treatment to perforated experiments, if the perforated expanding is too large to be straightened. After straightening, the transmission device is sent to the flaw detector for flaw detection experiment, and finally the label is affixed, the specification is arranged and placed into the warehouse.
Round tube blank → heating → perforation → three-high cross rolling, continuous rolling or extrusion → tube removal → sizing (or reducing) → cooling → straightening → hydrostatic test (or flaw detection) → marking → storage seamless steel pipe is made of ingot or solid tube blank through perforation into capillary, Then made by hot rolling, cold rolling or cold dial. Seamless steel pipe specifications with the outside diameter * wall thickness mm number.
The outside diameter of hot-rolled seamless pipe is generally greater than 32 mm, the wall thickness is 2.5-200 mm, The outer diameter of cold-rolled seamless steel tube can be 6mm, the wall thickness can be 0.25mm, and the outside diameter of thin-walled pipe can be 5mm. The thickness is less than 0.25mm. The size precision of cold rolling is higher than that of hot rolling.
General seamless steel pipe is 10, 20, 30, 35, 45 and other high-quality carbon steel 16Mn, 5MnV and other low alloy steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot rolled or cold rolled. 10, 20 and other low carbon steel seamless pipe is mainly used for fluid delivery pipeline. 45, 40Cr and other carbon steel made of seamless pipe used to manufacture mechanical parts, such as cars, tractors of the force parts. General seamless steel pipe to ensure the strength and flattening test. Delivery of hot-rolled steel pipes in hot-rolled or heat-treated condition; Cold rolling is delivered in heat treated condition.
Hot rolling, as the name implies, the temperature of the workpiece is high, so the deformation resistance is small, and large deformation can be achieved. Take the rolling of steel plate as an example, the thickness of continuous casting slab is about 230 mm, and the final thickness is 1 ~ 20 mm after rough rolling and finishing rolling. At the same time, because of the small width-to-thickness ratio of the steel plate, the size precision requirement is relatively low, and the shape problem is not easy to appear. For organizational requirements, generally through controlled rolling controlled cooling to achieve, That is to control the starting and finishing temperature of finishing rolling. Round tube blank → heating → piercing → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → hydrostatic test (flaw detection) → marking → storage.