The purlin installation shall be suspended after the installation of steel support ties, horizontal supports and inter column supports and the adjustment of the main body of the steel structure. The purlin bracket shall be welded on the steel beam according
to the dimensions shown in the figure, and the purlin bracket shall be welded and fixed according to the line. The welding position of purlin brackets in the same column shall be in a straight line and perpendicular to the steel beam column.
For the roof with a slope less than 1:12.5, pay attention to eliminate the roof irregularity caused by the deflection of steel beam during purlin installation. The tension bar between purlins plays a stabilizing role on the purlin. During installation,
the nuts at each end of the tension bar on both sides of the purlin shall be tightened to straighten the purlin. The welding operation must be stopped by the certified welder.
E4303 welding rod with diameter of 3.2 is adopted; The welding machine adopts AC welding machine with welding current of 100 ~ 130a. Before welding, check the quality certificate of welding rod and adjust the welding machine current. Check the quality
of the surface of the welding part, and welding can be carried out before it is qualified. Electrodes shall be stored in a monotonous and well ventilated place.
The weld size shall be constructed according to the construction drawings. Prevent outdoor welding in rainy days. Visual inspection of weld appearance quality shall be suspended after welding. The welding wave of the weld shall be uniform, and there shall
be no cracks, incomplete fusion, slag inclusion, undercut, burn through and other defects. After welding, the coating shall be cleaned, and two coats of