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saw pipe,stainless steel screen pipe,fbe pipe

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Welded Pipe-Submerged arc welding process: single-sided welding of butt joints,boiler tubes,casing tubing,smls pipe
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Welded Pipe-Submerged arc welding process: single-sided welding of butt joints

Date:2022-09-28View:280Tags:saw pipe,stainless steel screen pipe,fbe pipe

Welded Pipe-Submerged arc welding process: single-sided welding of butt joints

In submerged arc welding butt welding, the weldment can be provided with V-shaped, I-shaped and U-shaped grooves, which can not only ensure the penetration depth, but also control the fusion ratio and forming. The I-shaped groove can penetrate the weldment below 20mm at one time. When the plate thickness exceeds 14 ~ 16mm and penetration is required, V-shaped and U-shaped grooves shall be opened on one side. Several common methods of single-sided welding are as follows:


Single side submerged arc welding for root sealing or root backing

Due to the limitation of welding structure, it is not easy to use double-sided welding. Electrode arc welding can be used at the root, and then submerged arc welding can be used to ensure the weld depth.

The groove can be made on the weldment, and the bottom layer can be welded by electrode arc welding to ensure that the root is welded on one side and formed on both sides, and then the filler layer and cover layer can be welded by submerged arc welding.

Submerged arc welding single side welding double side forming

The weldment shall be fully welded at one time with strong welding current to achieve the purpose of forming. In order to weld the weld at one time and form on both sides, reliable gaskets shall be used to support the liquid metal in the molten pool to prevent the molten metal from burning through. In order to ensure the weld quality, the gaskets shall maintain their own shape under the high temperature of the molten pool to avoid burning through and prevent the liquid metal from flowing out, Control the weld width and residual height evenly. The gaskets used now include copper pad, flux pad and ceramic pad.

Copper pad: pure copper is used as the pad with good thermal conductivity. It is an ideal pad material. The copper pad is a forming groove with the same shape as the back of the weld.

During welding, flux is spread in the groove of the copper pad to play the role of flux pad and protect the copper pad from the direct effect of arc. This process is not sensitive to the assembly quality of weldments and flux support. It is divided into fixed type and mobile type according to the size and attachment mode of the copper pad.

The length of the fixed copper pad is longer than the weld length. During welding, the copper pad is fixed and can be fixed with an electromagnetic platform to make the copper pad stick to the weldment. Due to the limitation of the length of the copper pad, the weld cannot be too long.

The length of the movable copper pad is slightly longer than the length of the welding pool. During welding, it slides with the welding head at the bottom of the weld, also known as the copper slider. The copper slider is tightly fixed on the back of the weld by the tension spring on the welded joint through the root gap of the weldment.

The length of the sliding block will not limit the welding length. Due to the small length of the copper sliding block, poor heat dissipation and easy oxidation, it shall be cooled with water, and the weld groove shall have sufficient clearance and specially designed welding head.

Flux pad: the flux pad set off by the self weight of the weldment. The size and uniformity of the supporting force of the weld pad and the uniformity of the root gap determine the weld formation.

The flux pad can prevent the loss of molten pool metal. The use of fine-grained flux can not ensure the uniformity of support force if the flux particle size is uneven, and the formation of back weld is uneven, which will lead to welding defects.

Copper pad method and flux pad method are applicable to fixed welding and flat welding positions. Ceramic pad method is used for welding without fixed curved surface.