Pipe coupling according to the pipe end can be divided into: light pipe (pipe end without threads) and threading pipe (pipe end threaded). Car wire tube is divided into: general threading pipe and threading pipe end upsetting. Thick threading pipe can be divided into: EUE (with external thread), internal upset (with internal thread) and internal and external thickening (with external threads), etc. threading pipe. If you press threading pipe thread type can be divided into: ordinary cylindrical or conical screw thread and other places of special threading pipe. In addition, according to user needs, threading pipe is generally equipped with fittings delivery.

1, Tube heating The average heating to stop the rapid rise and fall of temperature. To adhere to a smooth landing every time the temperature slowly, the temperature does not exceed the maximum landing 30 ℃. 2, Mandrel mill The average wall thickness of the thick-walled tubes and solid billets, so that the probability of a significant reduction in the mandrel bending deformation, can be useful for the progress of the wall thickness precision steel pipe. 3, Precision of the mandrel Mandrel outer precision control at ± 0.1mm, straight degrees mandrel deflection does not exceed 5mm. Welding, finishing pierce a pin positioned between two sections of the mandrel, in order to avoid the formation of solder total straightness deviation is too large. 4, Perfect process Perfect process, to avoid the center and pull the thin wall thickness by Haou transcend the limitations of the control condition seizures, progressive wall thickness accuracy. 5, Centering rollers Determining whether the centering roller assembly in place, adjust the rollers hold the central core, open angle and various initiatives ashamed size consistent in the middle to hold the core roll rolling line. 6, Piercing mandrel Normal Select piercing mandrel outer diameter Φ108mm-Φ114mm, wall thickness and wall thickness requirements ≥25mm average of thick-walled tube. 7, Intermediate rolling line Ensure that punch line and the middle of rolling the car in the middle perforation lines consistent and prevent "rolling on" or "rolling down" so that the tube adhere average force at the time of perforation. 8, Things rolling Head wear on the guide plate and roller rolling things to change in real time. 9, Rolling means something Roller distance, middle distance necessary to guide the rolling line. Guarantee and roll away from the guide wire in the middle of the middle of the piercing and rolling line, namely the upper and lower roller pitch equal distance about equal to the guide. In the straight seam steel pipe production process, because the primary process is in a hot state, so the heating operation is resolution product quality is very important process. This operation is the key blank is heated uniformly heated to a temperature suitable for processing. Heating will be wrong in the outer surface of the tube surface may exhibit cracks, folds and migraine pain and other waste reason. Because a great impact on the quality of the perforation, that is, when the temperature of the process piercing is an important condition affecting the quality, it is generally the temperature of the billet piercing working is to manipulate. The second key is to try to reduce the heating operation scale quantities. Especially in hot kneading the elbow, leaving the surface quality of life several things and kneading pipe, pleading even more severe.

Surface NDT methods of straight seam steel selection principles: magnetic iron pipe should be used in magnetic particle testing; non-ferromagnetic steel should be used in penetration testing. Delayed cracking tendency of welded joints, the surface should be non-destructive testing after welding cooling certain time; reheat cracking tendency of welded joints, the surface should be in non-destructive testing and post-weld heat treatment once each. Surface non-destructive testing applications in accordance with the standard requirements that detects objects and applications in general as follows: (1) An outer surface of the tube material quality inspection. (2) Important butt weld surface defect detection. (3) Important fillet surface defect detection. (4) Important socket weld and jumper tee branch pipe defect detection. (5) Pipe bending surface defect detection. (6) The material tends to quench detection larger groove welded joints. (7) The design temperature is below zero or non-austenitic stainless steel pipe beveling detected 29 degrees Celsius. (8) The provisions of the double-sided weldment after weld gouging gouging detection (9) When using oxyacetylene flame cutting jig welded pipes alloy hardening tendency on when grinding parts defect detection.

Line pipe used plates 60 to 70 years using the Anshan Iron and Steel and other major manufacturers A3,16Mn, with diameter pipeline delivery pressure increases and progress strength steel can not meet demand. 80 years after each oil pipe plant started by the United States API standard production pipeline steel, because of the domestic pipeline board manufacturing plant immature technology, mainly imported plate. Enter the 1990s, the domestic plate production line developed rapidly, Baosteel, Wuhan Iron and Steel, Anshan, Benxi Iron and Steel, Panzhihua Iron and Steel and other enterprises have developed and produced a series of high-grade steel X pipeline. In the domestic pipeline steel production process are: a conventional semi-continuous hot rolling, CSP continuous casting and rolling, plate units, Steckel unit. 1) Semi-continuous rolling mill: Includes 1 rack 5 rack Steckel mill and finishing mill. In the semi-continuous rolling mills, strip the finish rolling experienced hot-rolled steel strip from one end to the other end is substantially constant. On finishing mill time between passes is generally less than 3s. 2) CSP continuous casting and rolling: in CSP production line containing niobium, vanadium, titanium composite micro-alloyed carbon steel, the use of appropriate controlled rolling and cooling and coiling process can ensure the mechanical properties and microstructure of steel modern organizations meet the technical requirements of X60 pipeline steel, pipeline steel in line with modern trends. Our CSP continuous casting and rolling production line has been developed to X60 steel, while the United States and other foreign manufacturers CSP has developed and produced high-grade pipeline steel X60, X65 and the X70. Which process is characterized by the presence of thin slab centerline segregation, eliminate thin slab centerline segregation is to further improve the quality of key pipeline technical problems. 3) Plate Unit: The main production of heavy plate for LSAW pipe production, reliable straight seam submerged arc welded pipe, widely used in high-voltage transmission and gas trunk line. 4) Steckel: Steckel mill comprises a reciprocating roughing mill and a finishing mill 4 roll back and forth. In the finishing mill both sides of the conveyor line installed two hot roll mill. Output roller typically comprises a laminar cooling system and a take-up station. On the Steckel mill, thermo-mechanical history of the entire length of the strip on the significant changes, especially in the micro-alloyed steel production, will strongly influence the degree of recrystallization generated in the finishing mill, grain growth and precipitation, and cause the entire dramatic changes in the final microstructure and mechanical properties of the strip length. Which process is characterized by relatively low investment costs.

The raw material is rolled seamless round tube, tube embryos to go through a cutting machine cutting a length of about 1 meter blank, and by conveyor belt to the furnace heating. The billet is fed into the furnace is heated to a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is the key issue. After a round tube came out to go through the pressure punching machine wear air. Generally more common punch is tapered roller punching machine, punching machine such high production efficiency, product quality, perforated expanding capacity, can be worn a variety of steels. After perforation, round tube has been three-roll rolling, rolling or extrusion. To post extrusion detached sizing. Sizing high-speed rotary cone drill bit through the perforated steel embryo formed steel. Pipe inner diameter is determined by the outer diameter sizing mill drill length. Pipe by sizing after entering the cooling tower through spray cooling pipe after cooling, will be straightening. After straightening the steel conveyor belt to the metal detection machine (or pressure test) for internal testing. If the thick-walled seamless internal cracks, bubbles and other issues, will be detected. After the selection of steel but also through strict quality control manual. After the steel quality inspection, using spray paint on number, size, production batch number. By a crane into the warehouse.