1) Construction preparation

a. Operating conditions: The pipeline trench surface has been completed; the pipeline well is made of bricks.
b. Material requirements: The pipelines of various specifications and models are complete.
c. Main equipment: cutting machine, electric welding machine, polishing machine, electric hammer, etc.

2) Quality requirements

The allowable deviation of the vertical installation of the riser is 3mm per meter, and the allowable deviation of more than 5m does not exceed 8mm. The allowable deviation per meter of pipes installed horizontally is 1mm.
3) Pipe installation

1. Production and installation of pipe supports:
According to the drawing design, pipe positioning is carried out, and seamless steel pipe supports are prefabricated according to the site conditions. Drape the wires from the 25th floor and secure the brackets.

2. Pipeline installation:
The material is cut according to the design and on-site, and then the groove is beveled with a grinder, and the bevel angle is 60°~65°. Fix the processed pipe on the bracket, the gap between the two pipes is 1.5mm~2.5mm, and then weld.

There should be no bends at the welded joints, and the joints should not be misaligned during assembly. The welding position is generally 4 spot welding. After checking and straightening, try to use the free conversion method for welding.

4) Quality requirements

1. No branch pipe shall be welded at the welding seam, and no welding seam shall be allowed at the elbow;
2. The weld is straight and full, and the weld surface has no defects such as burn-through, cracks, obvious nodules, slag inclusions, and pores.
3. The welding waveform is uniform, and the pipe-to-port alignment deviation does not exceed 20% of the pipe wall thickness and does not exceed 2mm.

5) Safety Precautions

1. The shell of the electric welding machine must be well grounded, and the welding tongs and the welding handle must be well insulated.

2. Wear protective equipment when using the welding machine.