Seamless steel pipe is a hollow section with no joints around the strip steel. Steel pipe with hollow section, a large number of pipelines used to transport fluid, such as the transmission of oil, natural gas, coal gas, water and some solid materials, such as pipelines, etc.. Compared to such as steel pipe and solid bar of steel, in flexural torsional strength are the same, the weight is light, is a kind of economic section steel, widely used in the manufacture of structural parts and mechanical parts, such as drill pipe, automobile transmission shaft, self frame as well as the construction of the steel scaffolding. Steel pipe manufacturing annular parts, can improve the material utilization rate, simplify the manufacturing process, material saving and working hours, such as rolling bearing ferrule, Jack sets etc., has been widely made of steel pipe. Steel pipe or all kinds of conventional weapons indispensable materials, gun barrels are made of steel. According to the different shape of the steel pipe, it can be divided into circular pipe and shaped tube. Due to the condition of the same perimeter, the circle area is the largest, and the circular tube can be used to transport more fluid. In addition, the ring cross section is subjected to internal or external radial pressure, the stress is uniform, therefore, most of the steel pipe is a circular tube.

But, circular tubes have some limitations, such as in under conditions of plane bending, tube is not as good as the party, rectangular tube bending strength, some farm skeleton, steel and wooden furniture and so on the commonly used square, rectangular tube. According to different uses, it is necessary to have other shapes of cross section.

Production and manufacturing method

According to the production methods can be divided into hot tube, cold drawn tube, pipe, pipe extrusion etc..

1.1, hot rolled seamless pipe in the general production of automatic pipe mill. Solid tube blank after inspection and clearance of surface defects, cut into required length, the tube billet centering hole end wear, then rushed to the heating furnace, perforation of the punch. In perforated while continuing to rotate and advance, in the roll and immediate action, tube gradually form a cavity, called capillary. Sent to the automatic tube rolling mill on rolling. Finally, the whole wall thickness of the whole machine is fixed, and the size of the sizing machine is determined. The production of hot rolled seamless steel tube by continuous rolling mill is a more advanced method.

1.2, in order to obtain smaller size and better quality of seamless tube, cold rolling, cold drawing method must be used or combined. Cold rolling is usually in two roller mill, steel tube in variable cross section circular groove and immobility of the tapered plug is composed of an annular groove rolling. Cold drawing was usually in the 0.5 ~ 100T single chain or double chain drawbench.

1.3, the extrusion method is about to heat the tube blank in a closed extrusion cylinder, the perforated rod together with the extrusion rod movement, so that the extrusion parts from the smaller die out of the hole. This method can produce smaller diameter steel tube.

Two, materials and standards

(A333 ASTM A106/A53/API 5L GR.BX46 X52, Q345D ASTM, Q345E)

1 general purpose ASTM A53 GR.B seamless steel tube, steel: SA53 B specifications: 1/4 "-28" 13.7-711.2mm.

2 high temperature operation of seamless steel tube for ASTM A106 GR.B, No. SA106B, specifications: 1/4 "-28" 13.7-711.2mm.

API SPEC 5L, 3 B, X42 pipeline steel, X46, X52, specifications: 1/4 "-28" 13.7-711.2mm.

4.ASTM A106/A53/API 5L GR.B, No. B, specifications: 1/4 "-28" 13.7-711.2mm.

The 5 heat exchanger and condenser for seamless low carbon steel ASTM A179 specifications: 3/4 ", 1"

6.-40 DEG C - 101 degrees Celsius temperature operating seamless steel pipe ASTM A333, ganghao: GR.A, GR.1, GR.6, GR.7, GR.3, specifications: 1 / 4 "- 28", 13.7-711.2mm

7 German standard DIN2448/1629 seamless steel tube, steel: St37, St44, St52, specifications: 1/4 "-28" 13.7-711.2mm.

13.7-711.2mm. Heat resistant steel seamless steel pipe (heat pipe) DIN17175-1979, steel, carbon structural steel St35.8-St45.8/I, St35.8-St45.8/III, alloy structure steel 15Mo3,13CrMo44,10CrMo910, specifications: 1 / 4 "- 28"

Seamless steel pipe GB/T8162-1999, with 9 steel structure: 10#, 20#, 35#, 45#, 16Mn (Q345), specifications: 6-720*1-70mm.

10 fluid transport GB/T8163-1999, seamless steel pipe steel: 10#, 20#, 16Mn (Q345), specifications: 6-720*1-70mm

11 low and medium pressure boiler tube steel GB3087-1999, 10#, 20#:, specification: 6-720*1-70mm

12 high pressure boiler tube GB5310-1995, No. 20G, specifications: 6-720*1-70mm

Phi "and" DN "are generally used to represent the diameter difference is: DN nominal diameter, diameter of said outer diameter

Now the tubes are generally in an inch as the unit, the millimeter is just a relatively approximate, good to remember the number of.

Such as DN50 pipes should be 2 inch, 1 inch =25.4mm, 2 inches should is 50mm, then depends on the wall thickness of the pipe, spiral pipe are in more than 5mm. 5mm, for example, DN50 pipe diameter should be about 60mm.

Q345 seamless steel tube is in fact a kind of steel pipe material. Q is representative of the yield of this material is the first letter of the alphabet, followed by the number 345, which refers to the yield value of this material is about 345. And will increase with the thickness of the material to reduce the number of.

Naming method similar to Q235.

Q345A, Q345B, Q345C, Q345D, Q345E. This is the level of distinction, represented by the impact of the temperature is somewhat different! Q345A level, is not to do the impact; Q345B level, is 20 degrees at room temperature impact; Q345C level, is 0 degree impact; Q345D level, is the 20 degree impact; Q345E level, is the 40 degree impact. At different impact temperatures, the impact values are also different.

In the plate, is a low alloy series. In the low alloy material, this material is the most common. Q345 seamless steel tube called the past: 16Mn seamless steel tube.