Nozzle operations before welding

When welding steel pipe, nozzle should do the following preparations:

(1) Removal of rust, dirt and grease at the interface.

(2) When using the steam pipe welding or mechanical cutting, straight section should ensure that, in order to ensure concentricity of the pipeline welding is completed, the cut should be removed before welding day glitches or attachments.

(3) When the opening tee holes in the pipe, it should be repaired mouth, residue should be cleaned inside the tube, saddle height of not less than the diameter of the opening half.

(4) In order to ensure that the wall of the welding process can be fully penetration, the nozzle should be made to groove, groove forms can be selected depending on wall thickness.

(5) Pipe wall thickness less than 3.5㎜following may beveling counterparts gap of 1 to 2 mm, the pipe wall thickness greater than 3.5mm must open groove, groove angle is generally 30°~ 35°blunt edge of 1 to 2 mm, a gap of 1 to 3 mm counterparts.

(6) It can be gas cutting groove forming (artificial opening groove) or groove machined groove after processing should remove slag dust and iron and steel file trim, until the exposed metallic luster.

(7) Different thickness welded pipe, pipe wall thickness difference between the two may not exceed 10% of the small wall thickness, maximum of 3mm (refers to two tube wall thickness difference), otherwise deal with a large thickness of the tube processing.

(8) When welding, the two adjacent pipe joints shall be spaced not less than 200mm, the minimum should not be less than the nominal diameter of the pipe.