Who can summarize the essential differences and characteristics of U-shaped grooves and XV-shaped grooves?

I am not a welder, but I also want to know. Please tell me in terms of the welding workload and difficulty, thank you.

The X-shaped groove is a double-sided groove, while the VU is a single groove. The single groove is used for plates that are not too thick, while the double groove is used for thicker plates. The V-shaped groove is easy to process, so it is commonly used. Too thick plates cannot be penetrated well during RT inspection, so double grooves are used and tested twice.

The groove forms of welded joints are as follows: Type I: This groove is a vertical corner edge, mainly used for steel structures with low pressure, as well as thin plates and seal welding. That is, the two ends of the interface are generally vertical and unpolished corners. ； Suitable for thin welding base metal. U-shaped: The root of this groove is relatively thin and is mainly used for thick-walled high-pressure pipelines, etc. That is, the interface needs to be polished into a U shape ； Suitable for thicker welding base metal. X type: that is, the interface needs to be polished into an X shape ； Suitable for thicker welding base metals. V type: that is, the interface needs to be polished into a V shape ； Suitable for relatively thin welding base metal. How to choose a bevel: In addition to ensuring weld penetration, the groove can also play a role in adjusting the proportion of base metal and filler metal, thereby adjusting the performance of the weld. The selection of the groove type is mainly determined based on the plate thickness and the welding method used, and also takes into account the size of the welding workload, welding material consumption, groove processing costs and welding construction conditions, etc., to improve productivity and reduce costs. According to the regulations of GB985-88, the groove forms commonly used in arc welding include no groove (I-shaped groove), Y-shaped groove, double Y-shaped groove, U-shaped groove, etc. When manual arc welding plates are butted with a thickness of more than 6mm, bevels are generally required. For important structures, bevels are required when the plate thickness exceeds 3mm. Workpieces with the same thickness often have several groove types to choose from. Y-shaped and U-shaped grooves only need to be welded on one side and have better weldability, but the angle deformation after welding is large and the consumption of welding rods is also larger. Double Y-shaped and double-sided U-shaped grooves are welded on both sides. They are heated evenly, have small deformation, and consume less welding rods. When the plate thickness is the same, double Y-shaped grooves save about 1/2 of the welding material than Y-shaped grooves, but they must be welded on both sides, so they are sometimes limited by the structural shape. U-shaped and double-sided U-shaped grooves have wider roots, are easy to penetrate, and consume less welding rods. However, the cost of groove preparation is high, and they are generally only used in important thick plate structures subject to dynamic loads.

People nowadays are getting lazy. Just look for any reference book on welding, and there will be an introduction to beveling. Besides, you can also tell something from the shapes of these letters.

You can read it clearly in GB/T985-2008!

U-shaped or V-shaped grooves are single grooves. U-shaped groove processing is more difficult than V-shaped grooves. When the thickness of the cylinder is relatively large, U-shaped grooves are used to avoid making the notch too large. When the thickness of the cylinder is thicker, X-shaped or double U-shaped grooves can be used. The equipment using this groove must have the possibility of internal welding. For specific thickness or which groove type to use under what working conditions, please refer to HG20583

Groove form (1) Butt joint: Butt joints are the most commonly used and most complete joint form among various welding structures. For example, the longitudinal and circumferential welds of boiler drums are butt joints. Generally speaking, when welding parts below 6 mm in manual arc welding and 14 mm in automatic welding, V-shaped grooves are used. V-shaped grooves are more convenient to process, but the workpiece is prone to deformation after welding. ； When the thickness of the steel plate is 12 to 60 mm, X-shaped groove can be used. ； U-shaped and double U-shaped grooves have less welding metal and less welding deformation. However, the processing of this kind of groove is more complicated and is generally only used in more important structures with larger plate thickness. For example, the circumferential seams of power station boiler drums welded by arc welding often use this form. In industrial boiler manufacturing, due to limitations of processing conditions, V-shaped grooves and asymmetric X-shaped grooves are generally used. For small-diameter drums where it is inconvenient to use automatic welding on the inside, V-shaped grooves are often used. 　　(2) T-shaped connector: When the plate thickness is less than 30 mm, the groove does not need to be made. If the joint needs to bear load, the groove form should be selected according to the thickness of the steel plate and the structural strength requirements. Single-sided V-shaped, K-shaped or double U-shaped grooves can be selected to ensure welding penetration. For boilers with working pressure ≥9.8 MPa, when the drum or header is connected to the pipe by a fillet weld, a groove must be made on the pipe end or drum or header regardless of the thickness. 　　(3) Corner joint: The connection between the drum and the head in small boilers belongs to this form. According to the thickness of the weldment and the preparation of the groove, the corner joint can be divided into four forms: no groove, single-sided V-shaped, V-shaped and K-shaped. 　　(4) Lap joint: The advantage of lap joints is that they do not require beveling, and the size requirements for joint assembly are not strict. 　　To sum up, choosing a reasonable welding joint groove form can not only increase the welding speed, improve welding conditions, reduce labor intensity, but also easily ensure the welding quality. Sufficient attention should be paid to the pressure vessel manufacturing process.

Excuse me, do the groove forms on both sides of the X-shaped groove have to be symmetrical? For example, the V-shaped groove on one side is deep and the V-shaped groove on the other side is shallow. Is this considered an X-shaped bevel or a double V-shaped bevel? What are the differences and connections between X-shaped grooves and double V-shaped grooves? :)

During design, the groove dimensions on both sides of the X-shaped groove are always completely symmetrical, but may not be completely symmetrical during actual processing. The depth of the two sides of the V groove is different. Before assembly, it is a processing deviation, and after assembly, it is a wrong edge. The blunt edge of the X-shaped groove is in the middle of the groove, and the blunt edge of the double V-shaped groove is on the outside or inside of the groove.

If you are designing, you don’t need to know the characteristics of several grooves, because which groove to use can be determined by the welding process qualification.； If you are engaged in welding, this is the most basic knowledge