Materials must enter factory along with Mill Test Certification, invoice, physics test report. After entry, there will be a double check from skilled workers. Only materials which pass the checking can be accepted. Rejects will not be allowed to entering factory.
Quality standard of steel structure components: 
1. Material preparing. Cutting sheets has no crack, dust, layered, default above 1mm.
2. Cutting precision. Roughness, uneven level, melting should be according with regulation. 
3. Drilling. Well shaped, and without burr.
4. Objection of welds. The objections of welds must be not deadly welds. 
5. Welding dreg. Welding dreg must be cleaned out and surface objections must be solved according to regulation.  
6. Frame appearance. There must be no distortion and there is no scar, smear and etc in frame surface.
7. High-strength bolt surface. There must be no ferric oxide, burr, scar, wrong smear, etc in the surface.
8. Marks. Marks must be complete, centre, precision position and fresh color. 
9. Painting objections. There is no cast, defaults and skip.
10. Painting appearance. The painting must be equal, and there is no discrepancy in color, no wrinkle in surface. The alterative paint coat due to cutting, welding or firing must be solved. The coating is no less than 120μm.