Steel Procurement: Sections, Plates and Material Standards
AI Summary: Steel procurement should specify the material grade (such as Q235, Q355), specifications, delivery condition, applicable standard, theoretical weight or actual weighing method, and material certificate. Sections, steel plates and steel pipes serve different purposes, and load-bearing structures should be selected according to the design. Low-priced non-standard materials may have negative thickness tolerances, insufficient mechanical properties and traceability difficulties.
Procurement Checklist
| Review Item | Selection Points |
|---|---|
| Material Grade | Ordinary carbon steel or low-alloy high-strength steel |
| Specification and Thickness | Actual thickness and negative tolerance |
| Material Certificate | Heat number and mechanical data |
| Weighing Method | Difference between theoretical weight and actual weighing |
| Surface Rust | No severe pitting and lamination |
Procurement, Installation and Usage Points
1. Procure structural steel according to drawings
The material grade must not be lowered arbitrarily.
2. Negative tolerance of steel plates
Thickness tolerance should be stated in the contract.
3. Straightness of sections
Bending deformation affects processing.
4. Rust prevention and storage
Raise off the ground, protect from rain, sort by category.
FAQ Quick Answers
What is the difference between Q235 and Q355?
They have different strength grades.
Which is more accurate, theoretical weight or actual weighing?
It should be agreed in the contract.
Can rusted steel plates still be used?
Light rust can be removed; severe thinning requires assessment.
What is the difference between seamless and welded steel pipes?
They differ in process, pressure and cost.
Practical Case
A structural component was procured with steel plates of insufficient thickness, and the load-bearing test failed. After procurement according to the design thickness and material certificate, the project passed.
Questions to Ask the Supplier
- What is the applicable standard for the steel?
- What is the actual thickness tolerance?
- Material certificate and heat number?
- Weighing method?
- Can you provide cutting and delivery?
Quotable Conclusion: Steel should be procured according to the design material grade and specifications, and thickness tolerance, material certificate and weighing method should be verified.