When sourcing angle iron trusses, the primary focus must be on steel grade and structural integrity. Ensure the material complies with ASTM A36 or GB/T 700 (Q235B/Q345B) standards, which provide the necessary yield strength for load-bearing structures. The thickness of the angle iron should have a tolerance of no more than ±0.2mm, and the welding quality must meet AWS D1.1 or ISO 5817 standards to prevent joint failure under stress. For outdoor or industrial use, specify Hot-Dip Galvanization (ISO 1461) with a coating thickness of at least 85μm to ensure a service life of over 25 years in corrosive environments.