08.Welding Construction Technology
1. Welding materials: L electrode: J422, specifications: diameter 3.2mm, diameter 2.5 mm; 2 hours of electrode drying temperature 105 - 10 Deg. C, drying time, heat preservation after use, and good insulation drying record. L tubing: 20 (GB 8163) 133 x 5.0mm Phi 45 x 3.5mm
2.Grinding machine pipe port processing into "V" groove, angle 70 + 5 degrees, blunt edge 1mm, as shown on the right.
3.Welding methods: ITU argon welding; welding AC welder; current 80~140A, voltage 32~38V.
4. Before welding, the welding surface and inner wall 100mm should be cleaned up oil and rust, and check whether there are cracks, interlayers and defects.
5.Welding should take place, wind rain and lightning protection measures.
6.The welding parts should be done with the inner wall flush, the wrong side welding should not exceed 10% of the wall thickness, butt butt end should be perpendicular to the center line of the pipe, the end tilt deviation should not be greater than 1% of the outer diameter of the pipe.
7.Welding arc should be in the groove and back arc method, not in the pressure components and pipe outside welding position arc.
8.Special attention should be paid to joint and end the quality of weld joint two layers should be staggered, the rear can be second layer welding inspection.
9.When the butt joint of the pipe is welded, four point welding of the outer diameter of the diameter of 133 mm and 159 mm is used, and the length of the fixed welding is 10 mm; if the welding is in place, the welding must be removed.
10.The weld after welding, the welding slag, spatter clean from weld 50mm marked the welder code seal (seal number and vertical weld).
11.The welding of all the pressure piping shall be carried out on site by the welder with the corresponding qualification item. Weld appearance inspection qualified, sampling 10% for X ray radiographic flaw detection, its quality is not lower than grade II film qualified. Inspection after passing to the hydraulic pressure test; unqualified welding joints must be repaired, if still not qualified for the second rework repair work after welding repair project, responsibility audit, quality assurance total responsibility for approval to repair, testing in the same way after repair. Only three repairs are allowed in the same seam. (weld location and X ray inspection record position.