Circular pipe of large diameter progressively formed of flat stock, the pipe having a single longitudinal seam is seam-welded by preparing welding grooves such that the inner groove is smaller in size and angle than the outer groove, sequentially carrying out submerged arc welding on the inner welding groove, and large current MIG welding to then first layer of the outer welding edge and a submerged arc welding to a second layer thereof.

Thick welded steel pipe of large diameter and production thereof

The invention provides a manufacturing method of a small-inner-diameter hollow spindle, which comprises the following steps: dividing a small-inner-diameter spindle into a plurality of spindle sections, respectively carrying out sectional forging, welding into an integral body, and carrying out stress-relief annealing on the small-inner-diameter spindle to finish the outer circle and the inner circle, thereby obtaining the finished product. The inner side of the welding joint of every two adjacent spindle sections is an assembly seam/spigot, and the outer side is a welding seam bevel. The welding process comprises the following two steps: carrying out bottoming and root welding in an argon arc welding mode, and filling and capping in a submerged arc welding mode. The invention implements sectional processing of the small-inner-diameter hollow spindle of a hydroelectric generating set, thereby greatly lowering the manufacturing cost, shortening the production cycle of the small-inner-diameter spindle, ensuring the welding quality of the small-inner-diameter spindle and relieving the manufacturing bottleneck of the small-inner-diameter spindle.

Manufacturing method of small-inner-diameter hollow spindle

PURPOSE:To eliminate welding defects and to improve welding efficiency in the stage of subjecting the inside surface of the groove of a blank steel plate to multi-electrode submerged arc welding by specifying root pass conditions and sepcifying the angle of the butt part on the outside surface side and the quantity of welding heat input. CONSTITUTION:The inside surface side 2 of a blank steel plate 1 for a steel pipe having a prescribed thickness is beveled 4 at such an angle alpha (about 25-40 deg.) at which a groove depth of about 0.4-0.6 times the plate thickness is attained. Such plate 1 is formed and the ends are butted to each other. The outside surface side 3 is partially tack welded and the groove 4 on the inside surface side is subjected to multi-electrode submerged arc welding. The 1st electrode current is set at <=750A and the current of the 2nd and succeeding electrodes is set at 0.70-0.90 times the electrode current just before the same as root pass conditions in this stage. The root pass is accomplished in such a way that the relation between the angle theta at the butt part on the outside surface side and the quantity of welding heat input (H.I.kJ/cm) attains -3.67theta+69<=H.I.- 3.67theta+99, when theta<=10 deg., 32<=H.I..-36.7theta+99 when 10 deg.<=theta<=16 deg. and H.I. <=32 when 16 deg.<=theta. The quantity of heat input for the 2nd and succeeding leayers is set according to the plate thickness.

Welding method of thick walled steel pipe for bending roll with high efficiency

PROBLEM TO BE SOLVED: To provide the welded joint of a steel sheet having excellent brittle crack propagation resistance which is property that a brittle crack is hard to propagate in the longitudinal direction of the welded joint, and also, even when the brittle crack propagates, it terminates before long. SOLUTION: In the multipass butt-welded joint of a steel sheet having excellent brittle crack propagation resistance, one or more weld layers or weld passes are arranged between a front welding layer and a rear welding layer in a separately spaced state from each other, wherein each of the weld layes or welding passes has different properties from those of the surrounding materials and can inhibit and terminate the propagation of a brittle crack. COPYRIGHT: (C)2008,JPO&INPIT

Multipass butt-welded joint having excellent brittle crack propagation resistance, and welded structure

The invention relates to a production process for an extra-large aperture super wall thickness square steel pipe A steel flat plate blank material with specified plate thickness and length and matched with the size of a final product is used, and bent through a bending machine, then the operation of rolling, closing, and overlap welding are performed on the blank materials, and the blank material is welded and reshaped through straightening, so that a final extra-large aperture super wall thickness square steel pipe is formed The production process is not limited by parent metal, and production can be performed according to the requirements for sizes of different specifications of square steel pipes; Compared with other square steel pipe production process which needs hot working, the production process saves energy consumption, is simple, reduces procedures and improves production efficiency, so that the strength of the produced square steel pipe is improved to a great extent The process technology fills a gap of the production of the domestic extra-large aperture super wall thickness square steel pipes, and has an important social significance

Production process for extra-large aperture super wall thickness square steel pipe

PURPOSE: To weld the thick steel plate, having a superior low temperature toughness, with a high efficiency, by forming the root pass bead with HIG welding using the wire, restricted C, P, S by multielectrodes automatic welding and carrying out submerged arc welding by heat input quantity of the wire, having a specific composition. COPYRIGHT: (C)1978,JPO&Japio

Automatic arc welding method for high efficiency multielectrodes of low temperature high toughness steel

PURPOSE: to obtain high quality weld zone excellent in the low temperature toughness at high efficiency, by employing the thin wire with the high current at welding the thick walled steel pipe, by preparing the mixed gas atmosphere from the inert gas added with CO 2 , and by giving a fast fine oscillation to the arc. CONSTITUTION: At welding work for forming the thick walled steel pipe, by first executing the MIG welding for the root layer and then by executing the SAW welding for obtaining the flush weld as the final layer; the mixed shielding gas atmosphere is prepared by adding CO 2 to the main mass of the inert gas, and the thin welding wire of diameter 0.8W2.4mm is employed. The distance l(mm) between the feeding tip and the groove bottom is set at l>10d+5, and the welding current I is set against the wire diameter (d) at the range, 500d≥I≥500d-150. Furthermore, a fast oscillation of frequency 3W30 cycle/sec and amplitude 1W15mm is given to the arc. Hereby, the arc is generated in the state of being throttled to thin and stiffened, the resistance against the magnetic blowout is improved, the directivity of the arc in the direction of wire extension is improved, and the smooth appearance of beads is obtained. COPYRIGHT: (C)1980,JPO&Japio

Welding method for forming thick walled steel pipe

PURPOSE: To improve the low-temperature toughness of the weld zone in the thick walled steel pipe, by finishing the surface layer of the weld zone according to the submerged arc welding, after carrying out the MIG welding on the groove face, prepared into a specified shape, by supplying a large welding current to the thin wire and by giving a vibration to this thin wire. COPYRIGHT: (C)1978,JPO&Japio

Welding method for manufacture of thick walled steel pipe

PURPOSE: To form the weld zone superior in the low-temperature toughness depending onone-pass-welding worked from both surfaces of the weld zone, by welding under an optimum combination of the groove shape and the welding method, in the welding of the thick-walled large diameter steel pipe. COPYRIGHT: (C)1978,JPO&Japio

Kosaburo Otani

Papers

Automatic arc welding method for high efficiency multielectrodes of low temperature high toughness steel

Welding method for forming thick walled steel pipe

Welding method for manufacture of thick walled steel pipe

Welding method for manufacture of thick-walled large diameter welded steel pipe

Schweissverfahren zur herstellung von stahlrohren