Nozzle Processing before Welding

In the daily pipeline welding, in order to obtain the high quality welding effect, the welding preparation work is also a very important step besides the good welding equipment and the welder. What do we need to do?


(1) clean up the rust, dirt and grease at the nozzle.
(2) the cross section of the steel pipe with steam welding or mechanical cutting should be straight to ensure the concentricity of the pipe to be completed, and the cutting and welding before the burrs or accessories are removed.
(3) when the three holes on the pipe are opened, they should be carried out in the mouth, and the residual residue in the pipe should be removed. The saddle opening height should not be less than 1 /
(4) to ensure that the pipe wall can be completely welded in the welding process, the nozzles should be made into grooves, and the grooves can be selected according to the wall thickness.
(5) pipes with wall thickness less than 3.5mm of less than 3.5mm are not trench, the gap is 1 to 2mm. The pipes with wall thickness greater than 3.5mm must be ditches, the gutter angles are generally 30 to 35 degrees, the edges of the obtuse angle are 1 to 2 millimeters, and the gap is 1 to 3 mm.
(6) the groove forming can be processed by gas cutting (artificial bevel) or groove machine. After the groove is processed, the slag and iron oxide should be removed and the steel mesh is used until the metallic luster is exposed.
(7) the thickness of the two wall tube wall is not more than 10% of the wall thickness, and the maximum is not more than 3mm (the difference of two wall thickness). Otherwise, the treatment is related to the thickness of the tube to be treated.
(8) during welding, the distance between two adjacent pipe joints shall not be less than 200mm, and the minimum value shall not be less than the nominal diameter of the pipeline.