Welds are invisible once painted, yet they are the safety baseline of the whole structure. What really separates Class 1 from Class 2 welds?
In steel QC, welding is the most skill-intensive process — and the first one sacrificed in low bids.
Under GB 50205, welds are classified in three grades: Class 1 gets 100% ultrasonic testing (critical parts such as crane girder tension flanges); Class 2 gets 20% UT for standard members; Class 3 requires visual inspection only. Export projects under ISO 17635 or AWS D1.1 follow similar logic.
The most practical verification for buyers: ask the factory for welder qualification certificates (key positions must be certified) and UT reports, and include weld sampling in any third-party inspection checklist. All Xionglan export projects ship with complete welding quality documentation.
Shanghai Xionglan Steel Structure · Exported to 60+ countries · EN 1090 CE certified · Engineer reply within 24 hours
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