Seamless tube stamping processing, prone to mucosal and slip defects. The reason for the folding is due to the pursuit of high efficiency of the manufacturers, the amount of depression is too large, resulting in the ear, the next rolling to produce folding, folding products will crack after bending, seamless tube strength decreased. The reason is that its blank is adobe, adobe pores and more adobe in the cooling process due to the role of thermal stress, resulting in cracks, after rolling there are cracks. Cold cutting machine tonnage high, cut the end of the surface smooth and tidy, and pseudo-poor material due to poor quality, cutting the end of the face often have the phenomenon of meat, that is uneven, and no metallic luster. And because the false product manufacturers cut off the small head, head and tail will appear big ears. These defects should be completely removed, after the removal of the wall thickness and diameter should not exceed the negative deviation. In the removal of defects to ensure that the seamless tube wall with a corresponding thickness, there is no difference in thickness, to ensure that the seamless tube with a high quality assurance. Oil cracking pipes arc welding basic operation technology using contact arc method arc, there are two kinds of brushing and direct hit method. Draw the first method of the electrode at the arc, the wrist to twist it, like the match matches the electrode in the arc at a slight scratch about 20mm length, and then lift the height of 2 ~ 4mm ignition arc. Its characteristics are: easy to damage the surface of the weldment, easier to master, generally applicable to alkaline welding rod. The first hit the electrode at the arc, the wrist under the bend, so that the electrode gently tapping the workpiece, and then lift the height of 2 ~ 4mm ignition arc.

Hierarchical defects from the mechanism, it is generally believed that non-metallic inclusions in the tube will destroy the continuity and compactness of steel, serious inclusions even in the steel pipe inside the stratification phenomenon. The other is considered hydrogen induced cracks, that is, due to the hydrogen accumulation in the steel caused by the metal internal gas partial pressure is too high, in the circular tube to form white spots in the rolling process of the expansion of the cracks, and ultimately the formation of layered defects. In addition, the non-uniform deformation of the two-roll oblique rolling perforations produces stress that exceeds the plastic strength and causes stratification. In the case of strict control of smelting, the third case, the control measures are: 1, To improve the duct toughness Improve the cleanliness of molten steel, reduce the harmful inclusions; increase the proportion of equiaxed billet, reduce the center segregation and center loose; use a reasonable cooling system to avoid internal cracks within the slab; Slow cooling process to reduce the internal stress, so as to ensure that the tube and finished pipe material and mechanical properties to meet the technical standards. 2, Reasonable control of heating temperature By measuring the thermoplastic curve, select the optimum heating temperature. Tube heating should also pay attention to have enough insulation time to reduce the deformation resistance and improve the plastic toughness. 3, Reduce the roll speed The roll speed is the key parameter of the piercing process, and there is a critical roll speed that begins to appear in the process of the roll speed from low to high. When the roll speed is low, the tube is easy to form the cavity; when the roll speed is high, the tube and the capillary are easy to form the stratification defect. In order to eliminate defects in the tube and capillary layers, the roll speed should be reduced below the critical roll speed at which the stratification begins to occur.

1. Stainless steel plate if the surface of the workpiece is attached with oil, the thickness of the scale of the oil attachment and the thickness and composition of the other parts are different and carburizing. The carburized part of the base metal will be severely attacked by acid. Heavy oil burner when the initial combustion of oil droplets, if attached to the workpiece, the impact is also great. Therefore, the operating staff do not touch the stainless steel parts directly, do not make the workpiece stained with new oil. 2, The surface of the workpiece if the cold processing of lubricating oil, etc., must be in the trichlorethylene degreasing agent, caustic soda solution in the full degreasing and then rinse with warm water, and then heat treatment. 3, Stainless steel if the surface of debris, especially organic or gray attached to the workpiece, the heating of course, will have an impact on the scale. 4, The difference between the atmosphere of stainless steel furnace atmosphere in the local different, the formation of a scale will change, which is caused by acid pickling after the reasons for uneven. Therefore, in the heating, the furnace parts of the atmosphere must be the same. 5, The workpiece in direct contact with the heating, must be fully dried to use. However, after drying, such as placed at room temperature, in the case of high humidity, the water will still condense on the surface of the workpiece. So, it is best to dry before use. Before the remnants of the scale, after heating the remaining parts of the scale and the site of no scale, there will be the thickness of the scale and the composition of the difference, resulting in pickling after the surface is not uniform, so not only pay attention to the final heat treatment, but also pay full attention to intermediate heat treatment and pickling. The resulting oxide is different. Therefore, it is necessary to make the treatment member not directly in contact with the flame port during heating.

Common galvanizing method of seamless steel tube is divided into hot galvanized and electroplating two categories. Hot galvanized with wet, dry, lead and zinc, redox method. The main difference between the different hot-dip galvanizing method After the acid leaching of steel pipe, how to activate the surface of the pipe to improve the quality of galvanized. Production is mainly used in dry and redox method. Galvanized zinc layer surface is very smooth and dense, uniform organization; has good mechanical properties and corrosion resistance; zinc consumption than hot galvanized 60% to 75%. Electroplating zinc in the technical have some complexity, but the single-sided coating, inside and outside the surface coating thickness of the double-sided coating, and thin-walled tube galvanized, etc. are required to use this method.

SA213-TP347H stainless steel original manufacturing process make the steel with big grain size , the grain size of G.S No4-5 level. The coarse grain TP347H stainless steel is used in the boiler superheater and reheater components, and in the case of high temperature operation, the oxide formed by the oxidation of the inner wall of the tube is easily peeled off. The oxide is deposited at the elbow of the pipe, causing the tube to overheat or even explode. What is more serious is that the exfoliation of the scale into the gas turbine will cause serious corrosion damage to the gas turbine. Studies have shown that the prevention of austenitic stainless steel tube surface corrosion of an effective measure is to reduce the grain size, fine grain of austenite structure can accelerate the diffusion of chromium in the grain boundary migration and formation of a layer of oxygen in the steam Dense chromium-rich chromium oxide (Cr2O3), this chromium-rich oxide layer can prevent high temperature steam on the tube wall further oxidation. In order to improve the high temperature strength of austenitic stainless steel, it is necessary to increase the melting temperature. However, to improve the melting temperature will lead to greater grain size, in order to solve the high temperature strength and grain larger contradiction, Sumitomo company through the improvement of TP347H manufacturing process, access to high temperature strength fine fine grain TP347H. The difference between the fine grain process and the coarse grain process is that the new process conducts the softening annealing of the tube at a temperature higher than the final solidification temperature before the last extubation. The precipitation of a large number of Nbc particles during the high temperature softening annealing hinders the obstruction of the austenite grain growth during the final solidification process. The grain size of the fine grain of TP347H stainless steel is G.S No8. Ie SA213-TP347HFG. In order to further improve the high temperature creep strength, high temperature corrosion resistance and steam oxidation resistance of stainless steel tubes for boiler, Japan has invested a lot of manpower, material and financial resources. For the existing SA213-TP304H, SA213-TP347H, SA213-TP310H three (TP347HFG), HR3C (TP310HCbN) three kinds of new stainless steel. It is a new type of stainless steel with super-supercritical boiler with stainless steel.