Installation of DSAW steel pipe

1. Repair mouth
In order to ensure the quality of the welding, the welding is carried out before the full inspection and correction, so that the pipe end, bevel angle, blunt edge, roundness, etc., are in line with the requirements of the interface size, individual steel pipe needs In the field to do groove processing, the use of gas welding cutting, remove the slag and then grinding with a grinding wheel.

Counter operation procedures are: check the interface connector size → clear chamber → determine and adjust the longitudinal seam of the steel pipe staggered position → the first structural steel pipe straight → adjust the gap size of the counterparts → leveling the mouth → straight → straight line → spot welding

2. Welding
Interface welding using arc welding, once down the base, two times to survive, each weld are welded once, each layer of welding lead-off arc to be staggered.

A. Pipe joints should be first before the mouth, slag, tube end of the groove angle, blunt edge, clearance, should meet the specifications; not in the gap between the gap welding or welding method to narrow the gap welding.
B. The mouth should be flush with the wall, the length of 300mm long ruler in the order of the inner wall of the interface in order to close the wrong port to allow partial inspection should be 0.2 times the wall thickness, and not more than 2mm.
C. The position of the longitudinal and circumferential welds shall meet the following requirements: The longitudinal weld shall be about 45 ° from the semicircle of the vertical line of the DSAW steel pipe; the welded seam of the reinforced steel pipe and the reinforcement ring shall be in the longitudinal direction Weld staggered, the spacing should not be less than 100mm; reinforcement ring pipe section of the circumferential weld should not be less than 50mm; pipe any location shall not have cross-shaped weld.
D. When positioning welding, the positioning of all weld pads (or grades) should be the same as the official welding, but the electrode diameter optional fine. The welding current of the positioning weld should be chosen to be larger than the formal welding, usually 10% -15% to ensure penetration.
E. Carbon steel pipe welding: weld quality must meet the relevant provisions of GB50268-97 4.2, the weld should be smooth, uniform width, root penetration, no obvious bump defects and undercut phenomenon, weld reinforcement should be higher than the tube Face about 2 mm, weld the edge of the groove 2-3 mm.
F. Pipe and flange welding, the pipeline should be inserted into the flange two-thirds, the flange and the pipeline should be vertical, the two coincides with the axis.