1、 Common quality problems of steel structure engineering: spatter, undercut, weld beading

 　　1.Suitable welding environment shall be selected;

 　　2.Welding materials must be kept properly to prevent moisture or peeling off of coating;

　　3.Adjust the welding angle, change the mode of strip transportation, readjust the welding current and welding speed;

 　　4.Try to reduce overhead welding or vertical welding, and use flat welding.

 2、 Common quality problems of steel structure engineering: crater, air hole and welding slag

 　　1.During welding, arc striking plate must be added to prevent crater;

 　　2.Before welding, the weld joint must be cleaned thoroughly, and there shall be no oil stain and other sundries;

 　　3.The flux, welding wire and welding rod must match the base metal, and the quality shall meet the standard;

 　　4.In multi-layer welding, the upper layer slag must be removed before the lower layer welding.

 3、 Common quality problems in connection of steel structure engineering: different tightening degree, uneven length of exposed nut of connecting rod with the same thickness

 　　1.Before installation or assembly, the deformation of the connecting parts shall be corrected to be straight. When tightening the bolts, it shall be carried out symmetrically from the middle to the outer side according to the correct procedures. The tools for using the fasteners must be consistent with the specifications of the bolts. It is strictly forbidden to use the joint force of two people or the method of increasing the arm rectangle with the sleeve to prevent over tightening or uneven stress; 

　　2.The length of bolts used shall meet the design requirements, and the length shall not be changed arbitrarily;

 　　3.In case of deviation of hole diameter or hole distance, it is necessary to punch or repair the hole and re make the hole. It is strictly prohibited to use gas welding or electric welding for expansion.

 Common quality problem: the torque value of high-strength bolt after tightening does not meet the requirements

 　　1.The contact friction surface of components must be treated in accordance with the design requirements and construction specifications, and the treated surface shall be protected with corresponding measures, and shall not be painted or stained;

 　　2.When tightening high-strength bolts, corresponding special spanners must be used.

 4、 Common quality problems in hoisting of steel structure engineering: foundation bolt displacement and screw damage

 　　1.Before embedding the anchor bolts, the setting out and positioning must be accurate. After rechecking, the concrete shall be poured. During the pouring process, a special person must be assigned to check the positioning of the anchor bolts;

 　　2.After pouring, the anchor bolt must be protected by box, box and other measures to prevent damage of screw thread;

 　　3.During hoisting, the steel column must be placed slowly to prevent bending or damage to the thread.

 Common quality problems: serious deformation of hoisting components and non-conforming installation dimensions caused by camber change

 　　1.Before hoisting, the components must be deformed and corrected;

　　2.When hoisting long components, measures must be taken to prevent instability, so as to ensure that the camber value does not change during hoisting;

 　　3.During the installation, if any deviation is found in the installation dimension, effective corrective measures must be taken, and it is not allowed to install by force or change the connection position or dimension without permission. 

 5、 Common quality defects in painting of steel structure engineering: coating quality does not meet the requirements

 　　1.During the derusting treatment of the component surface, it must be treated according to the design or construction specifications, and the quality must reach the required quality level;

 　　2.For the paint that is easy to precipitate, it must be stirred before use to prevent precipitation, resulting in uneven coating;

 　　3.The paint of the two manufacturers shall not be mixed as much as possible. If it needs to be mixed, it can only be used after passing the test;

 　　4.When proportioning, it is necessary to determine the type and quantity according to the test, and it is not allowed to mix driers and diluents at will, so as to prevent abnormal fast drying or slow drying, resulting in cracks, sags, wrinkles and other defects.