1G, 2G, 3G, 4G, 5G, 6G in welding terms?

Guide

Everyone basically knows what 1G, 2G, 3G, 4G, 5G networks mean. In fact, in the machinery industry, there is also a division standard for 1G, 2G, 3G, 4G, 5G, and 6G. This standard is the division of the weld position in the welding industry. Let's take a look today.

1. The position of the groove weld is divided into: 1G, 2G, 3G, 4G, 5G, 6G to distinguish between flat welding, horizontal welding, vertical welding, overhead welding, horizontal horizontal welding, and pipe inclination 45 degree fixed welding. .

2. Sheet fillet welds are divided into: 1F, 2F, 3F, 4F, respectively, ship type welding, horizontal welding, vertical welding, overhead welding.

3. Tube sheet or tube fillet welds are divided into: 1F, 2F, 2FR, 4F and 5F, respectively 45 degree rotation welding, horizontal welding (pipe axis vertical), tube axis horizontal (rotation) welding, butt welding tube axis level ( Fixed) welding.

Flat welding

Introduction to flat welding: 1G is flat welding

Welding characteristics:

1. The weld metal mainly relies on its own weight to the molten pool.

2. The shape of the molten pool and the metal of the molten pool are easy to maintain and control.

3. Welding the same thickness of the metal, the welding current in the flat welding position is larger than the current in other welding positions, and the production efficiency is high.

4. The slag and the molten pool are prone to mixing, especially when welding the fillet weld, the slag is easily advanced to form slag inclusions.

* Acidic electrode slag and molten pool are not easy to distinguish; basic electrode is relatively clear;

5. Welding parameters and improper operation are easy to form defects such as welding, undercut and welding deformation.

6. When the back side of the single-sided welding is freely formed, the first weld seam is likely to have an image such as uneven penetration process and poor back molding.

Welding points:

1. According to the plate thickness, a larger diameter electrode and a larger welding current can be used for welding.

2. When welding, the welding rod and the welding piece are at an angle of 60~80°, which controls the separation of molten slag and liquid metal to prevent the slag from appearing ahead.

3. When the plate thickness is ≤6mm, the butt joint welding generally opens the I-shaped groove. The front weld should be short-arc welded with φ3.2~4 welding rod, and the penetration depth can reach 2/3 of the thickness; before the back cover, It is possible to clear the roots (except important structures), but the slag should be cleaned up and the current can be larger.

4. If the slag and molten pool metal are not clearly mixed in the butt welding, the arc can be elongated, the welding rod can be tilted forward, and the action of pushing the slag to the back of the molten pool can be prevented to prevent slag formation.

5. When welding horizontal inclined welds, it is advisable to use up-slope welding to prevent the slag and molten pool from moving forward and avoid slag inclusion.

6. When using multi-layer multi-pass welding, it should be noted that the number of weld beads and welding sequence should be selected, and each layer should not exceed 4~5mm.

7. T-shaped, angled, lapped flat-angle welded joints. If the thickness of the two plates is different, adjust the angle of the welding rod to deflect the arc to the side of the thick plate so that the two plates are evenly heated.

8. Correct selection of the method of transport

When the welding thickness is ≤6mm, the I-type groove is butt-welded. When double-sided welding is used, the front weld is linear and slightly slower; the back weld is also linear, and the welding current is slightly larger and faster. some.

The thickness of the plate is ≤6mm. When opening other types of groove, multi-layer welding or multi-layer multi-pass welding can be used. The first layer of bottom welding should use small current welding rod, small standard current, linear type or zigzag moving rod. welding. For the filling layer welding, a larger diameter electrode and a short arc welding with a larger welding current can be used.

When the size of the fillet of the T-joint flat fillet is <6mm, single-layer welding can be used, and the method of linear, oblique ring or zigzag can be used. When the size of the solder fillet is large, multi-layer welding or multi-layer multi-pass welding is recommended. The bottom welding is carried out by a straight line method, and the filling layer may be provided with an oblique zigzag or a diagonal ring.

Multi-layer multi-pass welding should generally be welded by straight-line method.

Horizontal welding

Introduction to horizontal welding: 2G is horizontal welding

Welding characteristics:

1. The molten metal is easy to fall on the groove due to its own weight, causing undercut defects on the upper side and teardrop-type welds or incomplete penetration defects on the lower side.

2. The molten metal is easily separated from the slag, which is slightly like vertical welding.

Welding points:

1. The butt joints of the horizontal welding are generally V-shaped or K-shaped, and the butt joints with a thickness of 3~4mm can be welded on both sides of the I-type groove.

2. The small-diameter welding rod is used, the welding current is smaller than that of the flat welding, and the short-arc operation can better control the molten metal flow.

3. When welding thick plates, it is advisable to use multi-layer multi-pass welding in addition to the bottom weld.

4. When multi-layer multi-pass welding, pay special attention to controlling the overlap distance between the weld beads. For each lamination, the welding should be started at 1/3 of the previous weld to prevent unevenness.

5. Depending on the situation, maintain an appropriate electrode angle and the welding speed should be slightly flat and uniform.

6. Use the correct method of transport.

For the type I butt joint welding, the front weld seam adopts the method of reciprocating linear transporting; the slightly thicker part should adopt the linear or small oblique ring moving strip, and the back side adopts the linear type moving strip, the welding current can be appropriately increased.

When other gaps are used for butt welding, when the gap is small, the bottom welding can be carried out by linear transport; when the gap is large, the bottom layer is made of reciprocating straight line, and when the other layers are multi-layered, the inclined ring can be used. For multi-layer multi-pass welding, straight-line transport strips should be used.

Vertical welding

Introduction to vertical welding: 3G is vertical welding

Welding characteristics:

1. The molten pool metal and slag fall down due to their own weight and are easy to separate.

2. When the temperature of the molten pool is too high, the molten metal can easily form defects such as welding, undercut and slag inclusion, and the weld is not flat.

3. The root of the T-joint weld is likely to form an incomplete penetration.

4. The degree of penetration is easy to grasp.

5. Welding productivity is lower than flat welding.

Welding points:

1. Maintain the correct electrode angle;

2. The vertical welding is commonly used in production, and the special welding rod is used for the vertical welding to ensure the quality of the weld. The welding current is up to 10~15% lower than that of flat welding, and a smaller electrode diameter (<φ4mm) should be used.

3. Short arc welding is used to shorten the distance from the droplet transfer to the molten pool.

4. Use the correct method of transport.

When the T-type groove is butt jointed (usually used for thin plates), it is usually welded by straight, zigzag and crescent-shaped strips. The maximum arc length is not more than 6mm.

When other types of grooved butt joint vertical welding are opened, the first layer of welds is often welded with a crescent-shaped and triangular-shaped bar with a small amount of swing welding. Subsequent layers can be used in crescent or zigzag.

When the T-joint is vertically welded, the welding rod should have proper residence time on both sides and the top corner of the weld. The swing amplitude of the welding rod should not be greater than the width of the weld. The operation of the moving rod is similar to that of other groove forms.

When welding the cover layer, the shape of the weld surface is determined by the method of transport. For the weld surface, a crescent-shaped moving strip can be used for the slightly higher requirements; the flat surface can be used with a zigzag moving strip (the intermediate concave shape is related to the dwell time).

Overhead welding

Introduction to the back welding: 4G is the overhead welding

Welding characteristics:

1. The molten metal falls due to gravity, and the shape and size of the molten pool are not suitable for control.

2. It is difficult to transport the strip, and the surface of the weldment should not be flattened.

3. It is prone to defects such as slag inclusion, incomplete penetration, weld bead and poor weld formation.

4. The molten weld metal splashes and spreads, which is easy to cause burns.

5. The overhead welding is less efficient than other locations.

Welding points:

1. Butt welds are welded up. When the weldment thickness is ≤ 4mm, the I-type groove is used, and the welding rod of φ3.2mm is selected. The welding current should be moderate; when the welding thickness is ≥5mm, multi-layer multi-pass welding should be adopted.

2. T-joint welds for overhead welding. When the welding feet are less than 8mm, single-layer welding should be used. When the welding feet are larger than 8mm, multi-layer multi-pass welding is adopted.

3. According to the specific situation, adopt the correct method of transport:

When the size of the solder fillet is small, the linear or linear reciprocating transport strip is used, and the single layer welding is completed; when the solder fillet size is large, the multi-layer welding or the multi-layer multi-pass welding strip can be used, and the first layer should be linearly transported. For the remaining layers, the oblique triangle or oblique ring type can be used.

Regardless of the method of transport, the excessive weld metal to the molten pool should not be excessive.

The horizontal fixed port of the pipe is the 5G position.

Pipe 45° oblique weld is 6G position

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