1. Quality requirements of pipeline welding

a. Before installation, the pipes should be blown one by one to ensure that the inside of the pipe is clean;

b. The pipeline welding work shall be carried out by the welder approved by the labor bureau;

c. The pipeline welds shall be inspected according to the requirements of "Supervision Regulation on safety technology of hot water boiler";

d. The steel pipe shall be welded in half according to the center line of the pipe to prevent additional stress caused by heat concentration. Arc striking is not allowed on the non welding surface of the weldment. After each layer is welded, the welding slag and coating shall be removed by steel brush and ladle hammer, and the appearance inspection shall be carried out. If any defect is found, it must be removed and re welded.

e. For unqualified welding parts, repair welding measures shall be taken, and the repair times of welds at the same part shall not exceed two times.

f. Weld surface quality inspection: the weld surface shall be complete, the height shall not be lower than the base metal surface, and the weld width shall be 2-3mm beyond the edge of the groove.

2. Pipeline installation process

The installation process of the pipeline shall be horizontal and vertical. The elevation, slope and aspect of the pipeline shall meet the requirements of the design drawings. The matching tools shall be used when the pipeline is connected, and the strong matching is not allowed. The interface position shall avoid the wall and external casing. When the pipeline passes through the wall, the wall bushing shall be installed, and the gap shall be filled with asbestos rope.

The pipe supports and hangers shall be installed, fixed and adjusted according to the design requirements and specific site conditions. The position shall be correct, the installation shall be smooth and firm, and the normal thermal expansion of the pipe shall not be affected.