Application of Pipeline Automatic Welding Machine Wu Di (Liaohe Oilfield Oil Construction Second Company, Panjin 121010, Liaoning): pipeline welding; pipeline automatic welding machine; application; control of welding defects Surface automatic welding peak current / A410 ~ 450170-200 base value current / A75-2023.5-24.5 stay on both sides / R0.2-0.3 swing width is determined according to the width of the groove. It is the highlight in the construction of petroleum ground engineering.
In order to improve production efficiency, our company introduced two sets of automatic pipe welding machines at the end of 1999. Through the use of this equipment, we have basically grasped the welding process parameters of different pipe diameters and the prevention of common welding defects.
Both sets of equipment are products of Lincoln Corporation. Each set of equipment includes two parts: semi-automatic bottom welding machine, using Lincoln's second-generation inverter surface tension transition power supply (STT-), equipped with Lincoln's new microprocessor-controlled wire feeder (STTR-10); automatic pipeline welding Machine, using TRANSPULSSYNERGIC 450 (TPS450) power supply, PIPELINER round tube welding system.
= 20% mixed gas for protection. Semi-automatic bottom welding uses "1.2mm solid core wire, downward welding; automatic welding uses" 1.2mm flux cored wire, upward welding, and adopts water circulation cooling system. This set of equipment can weld all kinds of pipes over 168mm.
When using this equipment for the first time, the welding quality was difficult to guarantee, and some welding defects appeared. This is analyzed from the process point of view: the air holes are mainly generated during the bottom welding, and the back up is not timely and stays in the filling layer when filling the cover surface welding. Therefore, the gas flow and dry elongation must be strictly controlled within the specified range during the bottom welding, otherwise the gas protection effect is not good. When filling the cover surface welding, reduce the swing speed appropriately and increase the residence time on both sides to ensure that the pores of the root weld pass have more overflow time.
Both sides of the base metal weld should be cleaned of oil rust and dirt, preheated according to requirements, and the welding wire should be dried. This helps to prevent the generation of stomata.
When the bottom welding is not fully penetrated or fused, the roots are prone to not fully penetrated or fused. The main reason is that the pairing gap is too small, it is not easy to penetrate; the angle of the welding gun is not adjusted in time (including the lateral angle and the longitudinal angle), so that the two sides of the weld bead are not fused; the joint part is not handled properly, it is likely to be on both sides of the root weld Unfused. Therefore, when welding, the welder's attention should be highly concentrated, and the welding gun should be correctly operated. The joint part must be polished, sharpened at the center of the weld bead, and then the arc is directly welded on the weld bead.
During bottom welding, the heat input in the specification parameters should be set as large as possible, so as to ensure the energy input at the time of arc starting and avoid the occurrence of under-welding.
The interlayer fusion that occurs during the welding of the filling cover surface is mainly due to the excessively deep included angle at the welding toe portion during the bottom welding, which results in the failure to fully fuse the included angle during the filling welding and the failure of both sides of the weld bead Fuse. Therefore, when an excessively deep angle occurs during welding, the surface of the root bead must be properly polished, the angle should be removed before filling, and the arc residence time on both sides of the weld bead should be appropriately increased.
Because the fillet is welded upwards, when the welding trolley is welded at the bottom of the pipe, the spatter will fall onto the nozzle; when the trolley is welded to the top of the pipe, the splash will sometimes fall down and fall into the molten pool, causing welding . Therefore, the nozzle should be sprayed with an appropriate amount of anti-spatter agent before welding. During the welding process, pay attention to the spatter on the nozzle and clean it in time.
During the bottom welding with slag inclusion, the groove is too narrow, the gap is too small, the current is too large, etc., forming too deep rut marks, which will prevent the slag from floating. When filling welding, welding current and welding speed is too small, will produce slag inclusions. Therefore, if there are rut marks in the base welding, it must be polished. When filling welding, increase welding voltage and wire feed speed appropriately.
Through the use of pipeline automatic welding machine, the welding efficiency is greatly improved. Welding a "500mmx12mm joint reduces the time by half compared to manual welding. The specification parameters during the welding process are easy to control, less spatter, the weld is beautifully formed, and the labor intensity of the welder is greatly reduced.
In short, China's petroleum engineering construction welding automation has developed well, and it will surely become a new one in important engineering construction projects.
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