JP4788717B2 - Lateral submerged arc welding method and apparatus - Google Patents

Description

  The present invention relates to a lateral submerged arc welding method and apparatus for performing submerged arc welding on plate members abutted on each other in a lateral welding posture.

  Conventionally, submerged arc welding is known in which a welding wire and a base material are covered with a flux and an arc is generated in the flux to weld the base material (for example, see Patent Document 1). As a method of welding the horizontal joint horizontally by the submerged arc welding, there is a transverse submerged arc welding.

  As shown in FIG. 10, in the horizontal submerged arc welding, the two upright plate members 91 and 91 are butted up and down. An X-shaped groove portion 92 (X groove) is formed on the plate material 91, and a flux table 93 is provided below the groove portion 92. A flux F covering the groove portion 92 of the plate material 91 is sprayed on the flux table 93. A welding wire 95 is fed into the flux F from the welding torch 94, and an arc is generated between the tip of the welding wire 95 and the plate material 91 (groove portion 92) to weld the groove portion 92. .

  Here, when the submerged arc welding method is applied sideways, in order to prevent the molten metal from escaping to the back side of the plate (base material) due to the arc force during the first layer welding with respect to the X groove (or V groove). A temporary backing material 96 made of copper or ceramic is used.

  The backing material 96 prevents the molten metal from coming out to the back side, and the first layer weld metal 97 is formed.

JP-A-3-13274

  However, in the case of the method using the temporary backing material 96 described above, the penetration of the first layer welding is often insufficient, and oxidation of the back side portion of the groove portion 92 (the portion contacting the backing material 96) or copper When the backing material 96 is used, there is a problem that the back side of the groove portion 92 deteriorates due to the formation of a copper compound.

  Therefore, in order to form a sound joint, it is necessary to scrape off the first layer weld metal 97 by arc air gouging or the like until the sound weld metal is seen from the back side after the front side welding is completed.

  Moreover, inspection such as PT inspection (penetration flaw inspection) is necessary to confirm whether a sound weld metal has come out on the back side surface, which is very troublesome in the work process.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a lateral submerged arc welding method and apparatus capable of solving the above-described problems, preventing deterioration of the back side of the groove portion, and obtaining a good reverse wave bead.

  In order to achieve the above-mentioned object, the present invention butts the plate members up and down, forms a groove portion on at least one surface of the plate material, welds the groove portion sideways while covering the groove portion with a flux, In the horizontal submerged arc welding method for joining plate members together, a backside flux is sprayed on the groove back surface portion located on the back side of the groove portion to be welded, and the groove back surface portion is covered with the back side flux in advance, and the opening is opened. When arc welding the front part, the groove part is welded while applying heat to the back side flux to prevent deterioration of the groove back surface welded part.

  Preferably, when the groove portion is arc-welded, the back side flux is melted by heat from the arc to form a slag that covers the groove back surface portion.

  Preferably, a groove gap that is spaced apart vertically is provided in the groove portion, and when the groove portion is arc-welded, heat from the arc is applied to the backside flux through the groove gap.

  Preferably, a front side groove portion that forms the groove portion is formed on one surface of the plate material, and a back side groove portion that forms the groove back surface portion is formed on the other surface of the plate material, and the front side The said back side groove part is welded after welding of a groove part.

  Preferably, the plate material is made of low-temperature steel, and the welding wire used for the arc welding is made of a high Ni alloy.

  In order to achieve the above-mentioned object, the present invention butts the plate members up and down, forms a groove portion on at least one surface of the plate material, welds the groove portion sideways while covering the groove portion with a flux, In a lateral submerged arc welding apparatus for joining plate members together, a flux backing means for spreading a backside flux on the groove back surface portion located on the back side of the groove portion to be welded and covering the groove back surface portion with the flux And a welding means for welding the groove portion while arc welding the groove portion while applying heat from the arc welding to the backside flux to prevent deterioration of the groove back surface welded portion. Is.

  According to this invention, the outstanding effect that the deterioration of the back side of a groove part can be prevented and a favorable back bead can be obtained is exhibited.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The lateral submerged arc welding apparatus (hereinafter referred to as a welding apparatus) of this embodiment is applied when manufacturing a storage tank that stores a low-temperature liquid such as LNG, for example.

  The schematic structure of the storage tank of this embodiment will be described based on FIG.

  As shown in FIG. 1, the illustrated storage tank 70 is a double-shell tank, and includes an inner tank 71 for storing a cryogenic liquid, an outer tank 72 surrounding the inner tank 71, and these inner tanks 71. And a cold insulation layer 73 (perlite grains or the like) provided between the outer tub 72 and the outer tub 72.

  The inner tank 71 includes a dome-shaped ceiling portion 74, a cylindrical side surface portion 75 extending downward from the ceiling portion 74, and a bottom portion 76 that covers the side surface portion 75 from below.

  The ceiling portion 74, the side surface portion 75, and the bottom portion 76 are formed by joining together a plurality of plate materials (steel plates). The plate material is made of low-temperature steel such as 9% Ni steel, for example.

  As shown in FIG. 2, each plate material (hereinafter referred to as a side plate) 77 forming the side surface portion 75 has an arc-shaped outer shape. The side plates 77 are arranged in a ring shape in the circumferential direction and overlapped in the vertical direction (vertical direction) so as to be combined into a cylindrical shape as a whole, and the end portions in the circumferential direction and the end portions in the vertical direction of the side plates 77 are mutually connected. Joined by welding.

  In this embodiment, the edge part (vertical joint) of the circumferential direction of the side plate 77 is joined by TIG welding, and the ring bodies 81 and 82 are formed, and the ring bodies 81 and 82 (side plate 77) are step by step from the bottom. In addition to being assembled, the end portions (horizontal joints) of the assembled ring bodies 81 and 82 in the vertical direction are welded by lateral submerged arc welding along the circumferential direction for each step.

  In order to perform the horizontal submerged arc welding, the welding apparatus of this embodiment is used.

  A schematic structure of the welding apparatus according to the present embodiment will be described with reference to FIGS. In the following description, the side on which the side plate 77 is welded is referred to as the front side, and the opposite side is referred to as the back side. A virtual line along the end of the side plate 77 to be welded is referred to as a weld line L. In the horizontal submerged arc welding of the inner tank 71 described above, the weld line L is set between the lower edge of the uppermost ring body 81 and the upper edge of the uppermost ring body 82.

  The welding apparatus 1 is an apparatus main body (welding means) 2 for performing submerged arc welding, a moving means 3 that holds the apparatus main body 2 and moves the apparatus main body 2 along the welding line L, and is disposed on the back side of the side plate 77 for welding. And a flux backing means 5 for covering the back side of the weld line L (welded location) with a flux (hereinafter referred to as a back side flux) BF.

  As shown in FIGS. 3 and 4, the moving means 3 includes a frame 11 that holds the apparatus main body 2 and a traveling roller 12 provided on the frame 11.

  The frame 11 extends longer than the side plate 77 in the vertical direction. A traveling roller 12 is disposed on the upper portion of the frame 11, and the traveling roller 12 engages with an upper end portion (upper edge of the ring body 81) of the uppermost side plate 77. When the traveling roller 12 travels on the upper edge of the ring body 81, the frame 11 and the apparatus main body 2 move in the circumferential direction along the ring body 81.

  The apparatus main body 2 includes a welding torch 15 that holds and guides the welding wire 14, a welding power source 16 for supplying a welding current between the welding torch 15 (welding wire 14) and the side plate 77 (base material), and welding. A wire feeding device 18 that supplies the welding wire 14 to the torch 15, a control device 19 that controls the welding power source 16, the wire feeding device 18, and the like, and a flux (hereinafter referred to as a front side flux) on the welding line L (welding location). ) A flux supply device 20 for dispersing FF is provided.

  The welding torch 15 is arranged at the same height as the welding line L at the lower part of the frame 11. A conduit tube 21 that protects and guides the welding wire 14 and a power cable 22 that extends from the welding power source 16 are connected to the welding torch 15, respectively, extending from a feeding motor 26 (described later) of the wire feeding device 18.

  As shown in FIG. 5, the welding torch 15 is supported by the frame 11 via a welding torch adjusting means 24 for adjusting the position and angle of the welding torch 15. By the welding torch adjusting means 24, the height of the welding torch 15 (position in the vertical direction), the distance between the welding torch 15 and the side plate 77, the inclination angle (retraction angle) of the horizontal direction (welding direction) of the welding torch 15, the vertical direction The tilt angle (rotation angle wa, see FIG. 8) and the like are respectively adjusted.

  Returning to FIG. 3, the wire feeding device 18 includes a wire reel 25 around which the welding wire 14 is wound in a coil shape, and a feeding motor 26 for pulling out the welding wire 14 from the wire reel 25 and feeding it to the welding torch 15. Is provided. The feed motor 26 is provided with a wire straightening device (not shown) for straightening the welding wire 14 drawn from the wire reel 25.

  Here, as described above, in the present embodiment, the side plate 77 that forms the base material is 9% Ni steel, so that the welding wire 14 is made of a high Ni alloy (by weight, Ni 60 to 80%). used.

  The control device 19 is connected to the traveling roller 12, the feeding motor 26 and the welding power source 16, respectively. The traveling roller 12 has a control signal for welding speed, the feeding motor 26 has a control signal for wire supply speed, and a welding power source. Control signals for welding current and welding voltage are respectively output to 16.

  The flux supply device 20 includes a flux hopper 30 in which a granular front side flux FF is accommodated (stored), and a flux belt for holding the front side flux FF supplied from the flux hopper 30 at a welding line L (welding location). 31 and a collection means (in the illustrated example, a collection blower) 32 for sucking and collecting the front side flux FF from the flux belt 31.

  The flux hopper 30 and the recovery blower 32 are disposed at the upper part of the frame 11, and the flux belt 31 is disposed at the lower part of the frame 11.

  A supply hose 34 that extends downward to the flux belt 31 is provided in the flux hopper 30, and a recovery hose 35 that extends downward to the flux belt 31 is provided in the recovery blower 32.

  The flux hopper 30 or the supply hose 34 is provided with means (not shown) for adjusting the supply amount of the front side flux FF that is dropped by gravity and is supplied to the flux belt 31. The recovery blower 32 is connected to the flux hopper 30 to return the front side flux FF recovered from the flux belt 31.

  As shown in FIG. 5, the illustrated flux belt 31 includes a front pulley 38 disposed in front of the welding torch 15 in the welding direction (hereinafter referred to as the front) and a rear in the welding direction of the welding torch 15 (hereinafter referred to as the rear). And a heat-resistant (non-combustible) endless belt 40 that spans between the front pulley 38 and the rear pulley 39 and that receives the front-side flux FF.

  The front pulley 38 and the rear pulley 39 are rotatably supported by a support member 41 fixed to the frame 11, and the endless belt 40 abuts the side plate 77 at one end in the width direction. The flux belt 31 is engaged with the side plate 77 by friction so that the relative speed between the endless belt 40 and the side plate 77 is maintained at substantially zero when the welding apparatus 1 is moved (during welding), or The front and / or rear pulleys 38 and 39 are driven in conjunction with the movement of the welding apparatus 1.

  A supply port of the supply hose 34 is disposed above the front portion of the flux belt 31. In the illustrated example, a supply nozzle 42 that forms a supply port is attached to the end of the supply hose 34. The supply nozzle 42 is disposed at a distance between the front pulley 38 and the welding torch 15 and above the endless belt 40. The supply nozzle 42 is supported by the frame 11 via a supply nozzle adjustment means 43 for adjusting the front-rear position (interval with the welding torch 15) and the height position (interval with the endless belt 40) of the supply nozzle 42. The

  A recovery port of the recovery hose 35 is disposed above the rear part of the flux belt 31. Specifically, a recovery nozzle 44 that forms a recovery port is attached to the end of the recovery hose 35. The collection nozzle 44 is disposed rearward from the welding torch 15 and close to the upper surface of the endless belt 40. Similar to the supply nozzle 42, the recovery nozzle 44 is also supported by the frame 11 via a recovery nozzle adjusting unit (not shown).

  The front side flux FF is a melting flux that is melted by an arc and contains a deoxidizing agent (has a deoxidizing effect). For example, PFN-4 (manufactured by Kobe Steel) or Flux 10H (manufactured by Nippon Steel & Sumikin Welding Industries) is preferable as the front side flux FF.

  As shown in FIG. 2, the restraining means 4 is provided on the back side of the side plate 77. The restraining means 4 of the present embodiment is configured by a plurality of strong backs 46 arranged at intervals along the weld line L on the back side of the side plate 77.

  As shown in FIG. 6, the strong back 46 is made of a substantially rectangular plate material that is long in the vertical direction, and a notch 48 is formed on one of the edges (vertical sides) in the width direction. The strong back 46 is fixed to the upper and lower side plates 77 with the notch 48 positioned at the height of the weld line L. For example, the edge of the strong back 46 on the side where the notch 48 is provided is temporarily joined to the upper and lower side plates 77 in advance by welding or the like.

  The flux backing means 5 of the present embodiment is constituted by a flux receiving member 51 provided on the back side of the side plate 77 and extending along the weld line L.

  The flux receiving member 51 is made of an angle material with an L-shaped cross section. The flux receiving member 51 is arranged so that one flange (receiving flange) 52 is substantially perpendicular to the back surface of the side plate 77 and the other flange (guide flange) 53 extends upward from the receiving flange 52. . The receiving flange 52 contacts the side plate 77 (back surface) below the welding line L.

  The flux receiving member 51 is disposed in the notch 48 of the strong back 46, and spacers (for example, wedge-shaped members) 54 and 54 are sandwiched between the notch 48 and the flanges 52 and 53, respectively. Fixed.

  The back side flux BF is spread on the receiving flange 52 of the flux receiving member 51 and is held by the guide flange 53 so as not to fall from the side. The back side flux BF is the same type as the front side flux FF.

  Next, a lateral submerged arc welding method (hereinafter referred to as a welding method) of the present embodiment by the above-described welding apparatus 1 will be described with reference to FIGS.

  As shown in FIGS. 7 and 9, the welding method of the present embodiment is applied to double-sided welding of the side plate 77, and an X-shaped groove portion 61 (X groove) is formed on the side plate 77. The X-shaped groove portion includes a front groove portion 62 formed on the front side where welding is performed first, and a back side groove portion 63 where welding is performed after the front groove portion 62 is welded.

  In the welding method, the side plates 77 (plate materials) are butted up and down, and the front side groove portion 62 and the back side groove portion 63 are formed on both sides of the side plates 77, respectively, and the front side groove portion 62 is made of the front side flux FF. The side plates 77 are joined side by side while being covered, and in this embodiment, the back side groove portion 63 (groove portion back surface portion) located on the back side of the front side groove portion 62 to be welded first, When the back side groove portion 63 is covered with the back side flux BF in advance by spraying the back side flux BF and the front side groove portion 62 is arc-welded, heat from the arc welding is applied to the back side flux BF to provide the back side groove portion 63. The front groove portion 62 is welded while protecting the surface.

  Specifically, when arc welding the front side groove portion 62, the back side flux BF is melted by the heat of the arc to form the slag BS, and the weld metal WM of the back side groove portion 63 is covered by the slag BS. It protects and prevents deterioration (oxidation etc.) of the back side groove part 63. FIG.

  Therefore, in this embodiment, the groove portion shape and the target position of the welding wire 14 are set so that the arc heat from the welding wire 14 sufficiently reaches the back side flux BF.

  FIG. 8 shows an example of the groove portion shape and the target position of the welding wire 14.

  As shown in FIG. 8, the groove portion 61 of the upper side plate 77 is formed in a taper shape in which the plate thickness (length in the left-right direction in FIG. 8) becomes narrower as the lower end portion of the upper side plate 77 is lowered. At the same time, a route 64 extending in a substantially horizontal direction is formed at the lower end (upper end).

  Similarly, the groove portion 61 of the lower side plate 77 is formed by forming the upper end portion of the lower side plate 77 in a tapered shape and forming a route 64 at the upper end thereof. In the illustrated example, the taper of the groove 61 in the upper side plate 77 is set larger than the lower taper.

  A groove gap G is provided between the upper side plate 77 and the lower side plate 77 (route 64) so as to be vertically separated.

  In FIG. 8, t is the plate thickness, dw is the distance from the upper route 64 to the tip of the welding wire 14, dr is the route interval (the length of the groove gap G), and wa is the welding wire 14 (welding torch for the route 64). 15) The inclination angle (rotation angle).

  The side plate 77 of this embodiment has a plate thickness t of 11.9 to 50 mm.

  For this plate thickness t, the route interval dr is set to about 0.5 to 2.5 mm. This is because if the root interval dr is less than 0.5 mm, the arc is difficult to escape to the back side, and the back side flux BF is insufficiently melted. On the other hand, if the root interval dr exceeds 2.5 mm, the front side groove portion 62 is not sufficiently melted. It is.

  The rotation angle wa is set to about 10 ° to 25 °, more preferably 15 ° to 20 °. This is because when the rotation angle wa is less than 10 °, the arc is excessively pulled out to the back side and the front side groove portion 62 is not sufficiently melted. On the other hand, when the rotation angle wa exceeds 25 °, the back side flux BF is insufficiently melted. is there.

  The tip of the welding wire 14 is disposed above the upper route 64, and the distance dw is set to about 0.5 to 1.5 mm, more preferably 1 mm. This is because if the distance dw is out of the range of 0.5 to 1.5 mm, the backside flux BF is insufficiently melted.

  The groove portion shape, the rotation angle wa, and the target position of the welding wire 14 are not limited to those described above, but the thickness of the side plate 77, the material of the side plate 77 (base material) and the welding wire 14, the welding speed, and welding. It is appropriately set in consideration of current and voltage.

  Next, the example which applied the welding method of this embodiment to the welding of the side part 75 of the inner tank 71 of FIG. 1 and FIG. 2 is demonstrated.

  As shown in FIG. 2, the side surface portion 75 of the inner tank 71 is formed by forming a ring body 81 with a plurality of side plates 77 and stacking the ring bodies 81 on each stage. The ring bodies 81 are joined together by multilayer welding of both surfaces (inner peripheral surface and outer peripheral surface) of the side plate 77. In the illustrated example, multilayer welding of the ring body 81 is performed from the outer peripheral surface side, and the welding method of the present embodiment is used in the initial layer welding in the multilayer welding.

  Specifically, first, a new ring body 81 is assembled on the existing ring body 81, and these ring bodies 81 are temporarily fixed. A plurality of strong backs 46 are arranged at intervals in the circumferential direction on the inner peripheral side of the temporarily fixed ring body 81, and the flux receiving member 51 is fixed to the strong backs 46.

  Next, the back side flux BF is spread on the receiving flange 52 of the flux receiving member 51. The back side flux BF may be spread over the entire circumference of the ring body 81 in advance, or may be partially spread according to the progress of the front side welding.

  Next, the frame 11 that holds the apparatus main body 2 is attached to the outer peripheral side of the ring body 81, and the ring body 81 is first layer welded while moving the apparatus main body 2 along the ring body 81.

  Specifically, as shown in FIG. 7, the back side of the side plate 77 (the inner peripheral side of the ring body 81) completely covers the back side groove portion 63 with the back side flux BF, and the front side (ring body 81) of the side plate 77. The outer peripheral side) is arc-welded from the front side with the front side groove portion 62 and the tip of the welding wire 14 completely covered with the front side flux FF.

  By the arc of the arc welding, the front side flux FF and the back side flux BF are melted, and the heat input portions of the front side groove portion 62 and the back side groove portion 63 are covered by the slag FS, BS (see FIG. 9), The first layer weld metal WM is formed on the front groove portion 62.

  Here, since the side plate 77 is made of low temperature steel (9% Ni steel), deterioration due to oxidation is likely to occur during welding. In this embodiment, the back side groove portion 63 is covered with slag BS by the back side flux BF to prevent oxidation. In addition, since the back side groove portion 63 is deoxidized by the deoxidation reaction of the back side flux BF due to the heat of the arc, a good back bead is formed on the back side of the side plate 77.

  After the end of the first layer welding, the back side flux BF is removed on the back side of the side plate 77 to adjust the shape of the bead, and the back bead is ground by a grinder. On the other hand, the front side of the side plate 77 is continuously subjected to multilayer welding for a predetermined pass.

  After the multi-layer welding on the front side of the side plate 77 (the outer periphery side of the ring) is completed, the strong back 46 is rearranged from the inner periphery side to the outer periphery side, and the frame 11 and the apparatus body 2 are rearranged from the outer periphery side to the inner periphery side. Multi-layer welding is performed on the inner peripheral side, and the side surface portion 75 of the inner tank 71 is formed as described above.

  As described above, according to the lateral submerged arc welding method and apparatus of the present embodiment, it is possible to prevent deterioration of the back side of the groove portion 61 and to obtain a good backside bead.

  That is, the back surface groove portion 63 is completely covered with a normal flux (particularly not for the back groove portion) conventionally used in the submerged arc welding method using a temporary backing material made of copper or ceramic. By spraying as much as possible and performing normal welding from the surface in that state, a beautiful first layer weld metal is formed.

  The first layer weld metal formed by the method of this embodiment has sufficient penetration, the weld metal surface on the back side has a metallic luster, is hardly oxidized, is smooth, and is sound even if it is smooth with arc air gouging. A weld metal is obtained.

  In actual construction, it is necessary to slightly mold with a grinder etc. to form a good bead for the next welding from the back side, but arc air gouging etc. is performed to obtain a sound weld metal as before. It is not necessary, and compared to the grinder process for removing oxide after gouging and forming the back side groove part, only a simple grinder process is required in the present embodiment. .

  In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.

  For example, in the above-described embodiment, welding is performed on the groove portion formed in an X shape, but the present invention is not limited thereto, and for example, the groove portion may be formed in a V shape. Moreover, it is not limited to double-sided welding, and single-sided welding may be used.

  The backside flux BF can be sprayed as long as the backside groove portion 63 is hidden by the flux, and any spraying method may be used for this purpose.

  That is, the flux backing means 5 is not limited to the flux receiving member 51, and may be configured by, for example, a flux hopper 30, a flux belt 31, and a recovery blower 32 used for spreading the front side flux FF. In that case, it is desirable to dispose the flux belt 31 on the back side of the side plate 77 and provide the flux belt supply and recovery hoses for the flux belt on the flux hopper 30 and the recovery blower 32, respectively.

  Further, the back side flux BF can be reused similarly to the front side flux FF normally used on the front side.

  Moreover, in the above-mentioned embodiment, although the back side flux BF was sprayed so as to completely cover the back side groove portion 63, the back side flux BF in an amount that the slag BS by the back side flux BF covers the weld metal is not limited thereto. Just spray. For example, it can be considered that the back side flux BF is dispersed up to the height of the route 64 on the upper side of the groove portion 61.

FIG. 1 is a schematic structural diagram of a storage tank to which a lateral submerged arc welding method and apparatus according to an embodiment of the present invention is applied. FIG. 2 is a partial perspective view of the inner tank of the storage tank and the lateral submerged arc welding apparatus of the present embodiment. FIG. 3 is a side view of the lateral submerged arc welding apparatus of the present embodiment. FIG. 4 is a front view of the lateral submerged arc welding apparatus of the present embodiment. FIG. 5 is a side view of the torch and flux belt of the lateral submerged arc welding apparatus of the present embodiment. FIG. 6 is a front view of the strongback and flux receiving member of the present embodiment. FIG. 7 is a view for explaining the lateral submerged arc welding method of the present embodiment. FIG. 8 is a diagram for explaining a groove shape and a target position of the welding wire in the lateral submerged arc welding method of the present embodiment. FIG. 9 is a view for explaining formation of a weld metal by the lateral submerged arc welding method of the present embodiment. FIG. 10 is a diagram for explaining a conventional lateral submerged arc welding method using a backing material.

Explanation of symbols

1 Welding device (horizontal submerged arc welding device)
2 Main unit (welding means)
3 moving means 4 restraining means 5 flux backing means 14 welding wire 15 welding torch 31 flux belt 77 plate material 62 front side groove part FF front side flux BF back side flux 63 back side groove part (groove back surface part)

Claims (4)

With the match plate between the upper and lower, to form a front groove portion on the surface side thereof the plate material, a backside groove portion is formed on the back side, between the front-face groove portion and backside groove portion In the lateral submerged arc welding method in which a groove is provided that is spaced apart in the vertical direction, and is welded sideways while covering the front side groove portion to be welded with a front side flux, and the plate members are joined together,
Below the upper Symbol backside groove portion provided with a flux backing means, covered with previously said back flux the backside groove portion by spraying the back flux containing deoxidizing agent to the flux backing means,
When arc welding the front groove, the tip of the welding wire is positioned in the front groove adjacent to the groove gap, and heat from the arc is applied to the back flux through the groove gap. The transverse direction characterized by melting the back side flux and welding the front side groove part while forming a slag covering the back side of the molten metal in the back side groove part to prevent deterioration of the back side groove part. Submerged arc welding method. After welding of the upper SL front groove portion, sideways submerged arc welding method according to claim 1 for welding the rear groove portion. The lateral submerged arc welding method according to claim 1 or 2 , wherein the plate material is made of low-temperature steel, and the welding wire used for the arc welding is made of a high Ni alloy. With the match plate between the upper and lower, to form a front groove portion on the surface side thereof the plate material, a backside groove portion is formed on the back side, between the front-face groove portion and backside groove portion In the lateral submerged arc welding apparatus that provides a gap gap that is spaced apart vertically and welds the front side groove part to be melted sideways while covering it with a front side flux, and joins the plate members together,
Disposed below the upper Symbol backside groove portion, and tofu Lux backing means back flux is sprayed covering the rear groove portion in backside flux containing deoxidizing agent,
When arc welding the front groove portion, the tip of the welding wire is positioned in the front groove portion adjacent to the groove gap, and heat from the arc welding is applied to the back flux through the groove gap. with melting the backside flux, sideways submerged arc welding apparatus is characterized in that a welding means that formed form a slag which covers the rear surface side of the molten metal in the rear groove portion.

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