RU1324193C - Method of arc multi-pass welding of pipes - Google Patents

Description

(46) 07.02.3. Bull. Number 5

(21) 3972513/27

(22) 10.11.85

(72) V.V. Roshchin and B, A. Khavanov

(56) Copyright certificate of the USSR No. 270153, cl. B 23/31, 1966.

USSR copyright certificate No. 394175, cl. B .23 K 31/06, 1968.

S.N. Kisilev et al. Connection of pipes from dissimilar metals. M. Engineering, 1981, p. 33-34.

USSR author's certificate No. 1143554, class P 23 K 31/06, 1983.

(54) METHOD OF MULTIPLE ARC WAY 1TH PIPE WELDING

(57) The invention relates to methods of arc welding, mainly by a non-consumable electrode in a shielding gas environment without filler wire of butt joints of pipes of various metals, and can be used in power engineering and chemical engineering. com engineering, nuclear industry.

loyalty in other sectors of the national economy. The purpose of the invention is to improve the quality of the welded joint and the efficiency of the welding process by reducing the number of passes to obtain the required reinforcement and joint width. The method involves the preliminary implementation of the grooves on the back of the joint, the crimping passes, and then the main passage with the penetration of the joint for the entire weld. Waamuga thickness. . the extrusion pass is performed with through penetration of a part of the joint thickness welded by it to a groove, which is made of a predetermined depth. When welding

9 end joints of pipes with a diameter up to 40 mm

(L C grooves are made of a triangular cross-section, and when welding ring joints of pipes with a diameter of more than 40 mm - of a rectangular cross-section. As a result, the resistance of the joint to transverse shrinkage is reduced. 3 cp f-crystals, 6 ill.,

2 tab. 1 It relates to arc welding methods, mainly a non-consumable electrode in a gas medium without filler wire of butt joints of pipes made of various metals, and can be used in power engineering, chemical engineering, nuclear industry and 1 other industries. The purpose of the invention is to improve the quality of the connection and the efficiency of the Process by reducing the resistance of the transverse shrinkage of the seam during welding. FIG. Figure 1 shows stpps of pipes with a rectangular groove on the opposite side to welding; in FIG. 2.- the same, with a triangular-shaped groove; ; In FIG. 3 - the same, with a partially closed groove after crimping passes; in FIG. 4 - the same, with increased penetration depth; in FIG. 5 is the same after making a penetration pass through, having formed a reinforcement of the seam of width b and height, SJ in FIG. 6 - the same, with a through penetration. The method is carried out as follows. . At one of both ends of the pipes 1 to be welded, a complete groove 2 with a total width f (0.7-1.0) C, 1-) t and a depth I (-h), where 5 is the wall thickness of the pipe being welded, mm; h is the penetration depth of the first crimping passage, mm. The groove is made of a triangular profile. if the pipe diameter does not exceed 40 mm or rectangular, if the pipe diameter is more than 40 mm. Next, welding of the crimping passages 3 is carried out until the amplification of a predetermined value of 5 is formed, then welding of the pass 4 with through penetration and welding of the pass 5 with a penetration depth of 0.6 are welded. .0.8 (5. After completing the welding process, the joints are subjected to external inspection, measurement1, X-ray diffraction, metallographic studies and corrosion tests in 65% nitric acid solution at boiling point. 93 Example. 28x3 mm diameter pipes were welded. and 76xA mm from steel 12X18 110T on the SA-226 installation.The weld according to the technical documentation for pipes 28x3 mm should have a width of mm, height of reinforcement, 3 mm, and for pipes of 76x4 mm width and height of 6 mm. it is provided to carry out crimping passes with penetration depth, (mm), where tJ is the wall thickness of the pipe being welded in mm. Before welding, grooves were made on the back of each joint on pipes f 28x3 mm of triangular section, and on pipes / 76x4 mm of rectangular cross section. the grooves were made in accordance with the ratio, i.e., for pipes 28x3 mm, 5 J 3; 1.5-1.5 (mm), and for pipes 76x4 mm, 54 (mm), and the width of these grooves was made in in accordance with the relation (0.7-1.0) where S is the height of the reinforcement of the weld after making pressure passes in mm; b - the required width of the weld, mm, i.e. for pipes 1 / 28x3 mm 0.56-0.8 (mm), and for pipes 4 76x4 mm f 0.53-0.75 (mm). After assembling the joints, the crimping of the passages 3 was performed with through-penetration of part of the joint thickness they welded to the groove 2 in the following modes: 50 A, Vjg 8 m / h, V for pipes | 28x3 mm. J, 80 A, V, 10 m / h, and 11 V for pipe lengths Q 76x4 mm. Welding of the main passages 4 with the penetration of the joint over the entire weldable thickness 5 was carried out in a pulsed mode for pipes 4 28x3 mm: 90 A, / mp 2 C,, 0.8 s; for pipes 76x4 mm Jywn A, .y b5.c, t ,,, 0.6 s. After welding the main passage, each of the welded pipes performed an additional passage 5 with a penetration depth of 0.6-0.8 weld npi of the weld thickness of each joint. Dp

3132A1934

After the end of the welding process by biting ways. Data on all compounds passed the control are shown in the table. 1 and 2.

Table)

table 2

Claims (4)

It can be seen from the table that for the values of the coefficient of the width f of the groove corresponding to the values (0.7.,. 1.0, the required weld seam width b and the reinforcement S are achieved by the smaller number of welding passes compared to the known one, which indicates The efficiency of the process proposed for the multi-pass method of weld1G pipes Corrosion resistance of the weld, when performing an additional pass with a penetration depth (0.6 ... 08) is given in Table. 2. From the table. 2 it can be seen that the implementation of an additional pass 5 with a penetration depth (0.6-0.8) (mm), where § the thickness of the joint is welded, increases the corrosion resistance of the weld by 45-60%, Thus, the method of multi-pass arc welding pipes in comparison with the prototype allows to significantly increase the efficiency of the non-consumable electrode welding process by reducing the counteraction to transverse shrinkage, which significantly reduces the number of passes required to obtain the reinforcement and width of the weld required by technical specifications, which means Improves the productivity of the entire process and the quality of the weld. In addition, the implementation of an additional pass can significantly increase the corrosion resistance of the joint. Formula 1. The method of arc multi-pass pipe welding is practically non-melt. with a welding electrode without filler wire, in which grooves are made on the abutting edges from the side of the inner surface of the pipes, the joint is assembled and welded. first, crimping passes, and then the main passage with the joint penetrated to its entire thickness, which means that, in order to improve the quality of the joint and the process efficiency by reducing the resistance to transverse shrinkage of the seam during welding, the groove is made with depth l ((- h) and a width f (0.7.,. 1.0) is the height of reinforcement iijna after making the crimping passes, mm; -required width of the weld, mm; - the depth of penetration of the first crimping pass, mm;. - wall thickness of the pipe to be welded, mm, and each crimping pass made they are molten with through penetration of a portion of the welded joint thickness to the groove. 2 ,, The method according to claim 1, characterized in that when welding the ring butt joints of pipes with a diameter of up to 40 mm, the groove is made of a triangular section. 3. The method according to claim 1, which is related to the fact that when welding ring joints of pipes with a diameter of more than 40 mm, a groove is made of rectangular cross-section. 4. The method according to claim 1, characterized in that after the last welding of the main passage with penetration of the joint to the entire thickness to be welded, an additional passage is made from deep. penetration equal to O, 6 ... O, 8 of the joint thickness.  L v srig. 5 6