SU1706798A1 - Method of obtaining added projection of butted joint edges in parts to be welded - Google Patents

Abstract

The invention relates to gas-shielded arc welding and can be used in various industries and in construction. The purpose of the invention is to improve the quality of the formation of root welds when welding butt joints of pipes of various materials. The essence of the method is as follows. The filler element is buried in the beveled edges of the joint by an amount not more than half its diameter. The melting of the filler element is carried out by a pulsed arc with a stepwise movement of the electrode during a pulse. The height of the filler protrusion is determined by the formula: q (l62-2a H / 4KI, where q is the height of the filler protrusion, mm; d is the diameter of the filler element, mm; a is the opening width of the beveled edges, mm; h is the height of the beveled edges; K - the form factor of the filler protrusion CE 0,69; 0, I - the width of the filler protrusion, mm The method can be used when welding joints of hard-to-be refined steels. 4 Il., 3 Table 10.

Description

The invention relates to welding, in particular to welded joints for gas-shielded arc welding, and can be used in various industrial fields and in construction when welding butt joints of pipes made of steel and alloys.

The purpose of the invention is to improve the quality of the root seam when reconciling butt joints of pipes from various materials.

Figure 1 presents a part of the cutting compounds with the laid filler element; figure 2 - the shape of the filler tab; Fig. 3 shows the installation of the filler element on pipes with a diameter of more than 325 mm and in the lower and ceiling positions; Fig. 4 is a diagram of the arrangement of the end of the tungsten electrode at the time of melting the filler element.

The method is carried out as follows.

The inner diameter of the helix from which the filler rings 1 are made to produce a filler protrusion on butt joints of pipes 2 and 3 with a diameter of less than 325 mm is taken to be 1.3-1.5 times smaller than the outer diameter of the cylindrical surface at the welding site. rings during assembly and welding. If the helix diameter is less than 1.3 times, the spring properties of the ring decrease, and when the helix diameter is less than

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more than 1.5 times the installation of the ring during assembly is difficult.

For butt joints of pipes with a diameter of more than 500 mm, when receiving the filler protrusion from the inside, the pipes, the inner diameter of the helix takes 1.3-1.5 times the outer diameter of the cylindrical surface at the welding site also to ensure the spring effect of the ring. When deviating from the specified dimensions, either the spring properties are also reduced, or the installation of the ring during assembly is difficult.

The chemical composition and diameter of the welding wire is selected depending on the required provision of the alloying of the root weld metal, the formation of the inner surface of the weld and the ease of welding of refined steels.

The filler element 1, installed in the bevelled edges of the groove, is melted by a pulsed arc of tungsten electrode 4 with step-by-step movement during a pulse, while having the end of electrode 4 in the region bounded by the surface of the pipe and the outer part of the filler element.

During the step-by-step movement of the welding arc during a pulse, a stable melting of the filler ring is ensured, with further ensuring that the melted portion of the filler ring solidifies before the welding arc during a pause, when the strength of the welding current decreases while the electrode is stationary. This is necessary to hold the filler ring on the surface to be welded without the use of special tools.

By positioning the end of the tungsten electrode 1 in the process of alloying the filler ring in the region bounded by the surface of the pipe and the outer part of the filler element, the arc length (Ig) is required for a stable fusion of the filler ring to obtain a filler ledge of a given size.

When the end of the electrode is located above the outer part of the filler element, the filler element may melt without melting with the edges of the filler. There is no need to locate the end of the electrode below the surface of the pipe, in addition, in this case, electrode closures and impaired process stability are possible.

The filler element 1 is embedded in the beveled edges by an amount not exceeding half the diameter of the wire.

The maximum depth of the filler element 1 (, 5d) is required when welding steels with poor weldability (refined steel) to ensure

the largest fraction of the metal of the filler element (with good weldability) in the weld pool when welding the root seam. With a greater depth of deepening, the width of the opening of the bevelled edges increases with a simultaneous increase in the area of the groove and a decrease in the non-buried part of the filler element, which directly provides the specified dimensions of the filler

protrusion. Therefore, the amount of deepening, equal to half the diameter of the wire, is maximum.

The minimum depth value is limited by the minimum possible edge opening value provided by mechanical treatment (, 4-0.6 mm); possible only for well-welded steels and when no alloying of the root weld metal is required.

In addition, with a small opening of the edges, the filler element is poorly retained in the edges of the groove, nor does it ensure reliable fusion of the filler element with the edges of the groove.

The optimal value of the depth (for normally welded steels) should be considered the value (, 3 d). In this case, the filler element is well retained in the beveled edges of the groove 2.3 and reliably fuses with the edges.

The height of the filler protrusion is chosen from the ratio

L- (G -2a h 9 4k-e

where a is the opening width of the beveled edges, mm;

h - the height of the beveled edges, mm; d is the diameter of the filler wire, mm;

e is the width of the filler protrusion, mm;

g is the height of the filler protrusion, mm;

K - coefficient taking into account the mode of welding and the shape of the filler protrusion; kЈ 0.69: 0.73.

The filler protrusion on the edges of the butt joint groove for welding is carried out in the following sequence,

The initial data for calculating the production of the filler protrusion of a given size and shape are determined by the tables and determined by the tables.

 A standard welding wire with a diameter of 1.6; 2.0; 2.5: 3.0 mm, which is selected depending on the thickness to be welded and the specified dimensions of the filler tab (Table 1).

The dimensions of the filler protrusion (d, e) are determined by the technological capabilities of argon-arc welding, as well as the technological need for the further high-quality formation of the root weld without meniscus with smooth fusion with the edges of the groove and are selected according to Table 2.

The values of the coefficient (K) calculated for various ratios of height (d) and width (e) of the filler protrusion are given in Table 1.

The size of the gap (c) in the assembled joint is indicated in the technological documentation for welding. Welded pipe joints for automatic argon-arc welding with a diameter of up to 325 mm are usually assembled without a gap (the maximum allowable gap is 0.3 mm). Therefore, this gap size when using a filler element with a diameter of more than 2.0 mm can be ignored, and for accurate calculations and when using a filler element with a diameter of less than 2.5 mm, they take the average value of the gap. The gap in welded joints of pipes over 325 mm is also taken into account by the average. The values of the average gap for different pipe diameters are given in Table 1.

The depth of penetration of the edges (c) in size is usually 50% of the size of the blunting (Pi), while the remaining part of the unmelted edges (t) (Fig.9.10) should not be less than 1 mm to provide a filler ledge of specified dimensions at compulsory incomplete penetration of the edges being welded, which is ensured by the choice of welding mode.

The opening width of the beveled edges (a) is determined by Table 3, preset by the angle (a) of the bevel of the edges at the corresponding depth of the filler element in the base metal, depending on the material to be welded and determined by Table 1.

Example. The method of obtaining the filler protrusion was tested when preparing the edges of the pipes for welding of steel grade. 08Х18Н10Т with a diameter of 25-325 mm with a wall thickness of 2-16 mm, edges of pipes from steel grade 20 with a diameter of 25-426 mm with a wall thickness of 2-24 mm and edges of pipes from steel of the brand 08Х18Н12Т with a diameter of 560 mm with a wall thickness of 34 mm.

Pipe $ 57x3.5 mm, steel grade 08Х18Н10Т.

Baseline data (taken from Tables 1–3): diameter of the filler wire, 5 mm, dimensions of the filler protrusion, 4 mm. , 8 mm (with KHD.69); gap size in connection .1 mm; edge penetration depth, 5 mm; the depth of the filler element in the beveled edges .5 d; opening width of bevelled edges, 55,875 mm; accept, 0 mm.

The filler ring is made of welding wire brand Sv-08H19N110G2B with a diameter of 2.5 mm. The diameter of the helix from which the ring is cut 40-46 mm (Table 1) and the dimensions of the beveled edges are determined using the dependence

tg a

a +2 ab

l cr - 4 keg - 4 be 42 +2 -4 0.1

1.73

l 2U - 4 -0,69 -4.4 -0,8-4 -0,1 -0,5

a 60 °; a 4.0mm. The joint is assembled with the filler ring laid without tacking.

The melting of the filler ring is performed without removing the assembly tool (centralizer).

Modes of fusion ring type automatic STEP;

Pulse current, A65-70 Break current, A 20 Pulse duration, s 1.05 Pause duration, s 0.9 Pitch, mm 1.98 Arc length (distance of electrode from welded

surface) 0.6x (- .0.5 d)

Protective environmentArgon

After the melting of the filler element, the automat and the assembly tool are removed, since the joint is fixed by an annular tack. The dimensions and quality of the filler protrusion are controlled by a special device, 3-4.7 mm; 7-0.8 mm.

Similarly, pipe joints are assembled from steel grade 08Х18Н10Т, 08Х18Н12Т with a diameter of mm with a wall thickness of up to 6 mm, and also from steel of the VstZsp5, 10 and 20 steel with a wall thickness of up to 4.5 mm. A filler element in the joints of pipes with a diameter of 108-325 mm is fixed with tacks, the number of tacks is given in Table 2.

For low-carbon steels of the pearlitic class, an additive element of welding wire grade Mv-08G2S or Sv-08GSMT is used.

The specified dimensions of the filler protrusion depend on the requirements of the welding technology of the corresponding steel grade, wall thickness of the pipe parts, the diameter of the pipes and the spatial position of the joint during welding (Table 1). The filler protrusion is performed on the appropriate welding modes to obtain a predetermined penetration depth.

The use of the method is most advisable when performing in the rotary and non-rotatable positions of butt welded joints with reinforcement of the seam on the inner and outer side, eliminates defects such as pores and cracks in the welds, allows one-pass welding when performing welded joints from difficult-to-weld refined steels, allows welding joints with different outer diameters, as well as in the presence of a conical surface of one or both elements to be welded and with an inclined pipe elements (fittings).

The use of a compound with a filler ledge of the necessary alloying dramatically increases the efficiency of using automatic argon-arc welding in industry and construction, and especially in repairing the equipment of nuclear power plants, when it is necessary to shorten the residence time of personnel in the area with increased radiation.

Claims (1)

The invention of the method of obtaining a filler protrusion on the edges of a butt joint of parts for welding, in which a round filler element is placed on the bevelled edges of the groove and melted with a non-consumable electrode, in order to improve the quality of root formation. when welding butt joints of pipes made of different materials, the filler element is embedded in the beveled edges of not more than half its diameter, it is melted by a pulsed arc with traction movement of the electrode during the pulse, positioning the electrode end between the pipe surface and naruzh0 hydrochloric part filler member, and the height of protrusion of the filler is selected from ratios of lb2 -2 а h 94k-e where g is the height of the filler, mm; d is the diameter of the filler element, mm; a is the opening width of the beveled edges, mm; h - the height of the beveled edges, mm; k is the shape factor of the filler protrusion; , 69; 0.73 e is the width of the filler protrusion, mm five 0 08Х18НЮТ -M08Х18Н10Т (Sandvik) 08Х18Н10Т - 08Х18Н12Т 20  I - one; five 3; 7 - - - four; 8 2; 6 3; 7 3; 7 3; 7 3; 12 about 0.1 0.1 1.6 2.0 2.5 30 A9 60 FOR FOR FOR FOR FOR 38 - (5 А5 35 35 35 35 35 60 1.38 1.0 1.15 2.35 2.35 2.35 2.35 2.35 2.35 2.05 0.95 1.A5 2.1A 2.14 2.1A 2.14 2.14 1.1 1.6 2.2 A o 0.3 0.5 0.5 1.8 2.8  A, a 0.7 1.0 0.8 .1,0 .1,0 1.0 1.0 1.01, 0 1.0 0.7 , 0. , 0 , 0 , 0 , 0 , 0 , 0 0.73 0.73 0,69 0.7 0.7 0.7 0.7 0.7 0.7 0.7 OL71 0.7 0,69 0,69 0,69 0,69 0,69 0,69 0.6 0.7 0.6 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.6 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.25 0.3 0.5 0.3 0.3 0.3 0.3 0.3 0.3 0.3 ° .c 0.3 0.4 0.4 0.4 0.4 0.4 0.4 -j o SP J o so Table E table Continuation of table 3 Phie.1 B, 2 Edge with fusions Stable process Electrode Locking Editor S.Patrusheva W Fy Compiled by G. Tyutchenkova Tehred M.MorgentalKorrektor M.Demchik FIG. 2 Bb-cd-d 8 cd-f .f