Passivation (Stainless Steel)
Passivation is a chemical treatment applied to stainless steel fasteners to remove free iron contamination and restore the natural chromium oxide passive layer. Applied per ASTM A967 and AMS 2700. Essential for stainless steel fasteners used in food, pharmaceutical, offshore, and chemical process environments where maximum corrosion resistance is required.
| Standard | ASTM A967 / AMS 2700 (referenced) |
| Base Material | Stainless Steel (304, 316, 316L, Duplex 2205, Super Duplex 2507) |
| Salt Spray | 1,000+ hours (316L after passivation) |
| Thickness | 2–5 nm (molecular passive layer — not measurable conventionally) |
| Applications | Food grade, pharmaceutical, offshore marine, chemical process, desalination |
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Passivation is a post-machining or post-fabrication chemical treatment applied to stainless steel fasteners to maximise their natural corrosion resistance. Stainless steel derives its corrosion resistance from a thin, self-regenerating chromium oxide (Cr₂O₃) passive layer on its surface. However, machining, forming, and handling operations can introduce free iron contamination that compromises this layer — making passivation a critical quality step.
Asia Bolts Industries performs passivation on all stainless steel fasteners (304, 316, 316L, 316Ti, 317L, 904L, Duplex 2205, Super Duplex 2507) per ASTM A967 and AMS 2700.
Passivation Process: 1. Pre-clean: Alkaline cleaning to remove oils, cutting fluids, and organic contamination 2. Acid Treatment: Immersion in nitric acid (HNO₃) or citric acid solution to dissolve free iron • Method 1: Nitric acid (20–45% concentration, 20–60 min at 21–49°C) • Method 2: Citric acid (4–10% concentration) — preferred eco-friendly alternative 3. Water rinse and dry 4. Verification: ASTM A967 copper sulphate test or high humidity test to confirm passive layer integrity
ASTM A967 Practice Classifications: • Nitric 1: 20–25% HNO₃ at 21–32°C • Nitric 2: 20–45% HNO₃ at 49–60°C • Citric 1–4: Varying citric acid concentrations and temperatures
Key Outcomes: • Removal of all free iron from surface • Restoration of chromium oxide passive layer • Significantly improved resistance to pitting corrosion in chloride environments • Compliance documentation for critical oil & gas, food, pharma applications
All passivated stainless fasteners from Asia Bolts are supplied with passivation practice designation, test method used, and material certification per heat/lot.
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Packaging Information
📦 Standard: Cartons, wooden boxes or pallets based on quantity and customer requirements
🎁 Custom: Polybag + carton on request
🚢 Export: Fumigated pallets available
📋 Each box includes inspection certificate
Delivery Information
📦 Lead Time: Stock items: 1-5 days | Custom manufacturing: 7-30 days
🚢 Shipping Methods: Air freight, sea freight, or land transportation. FOB, CIF, DDP terms available.
📋 Full export documentation provided with every shipment: Commercial Invoice, Packing List, MTC, Bill of Lading, and Certificate of Origin
☑ Saudi Aramco Approved: Recognized vendor for critical upstream and downstream projects.
🔩 Custom Manufacturing: We produce non-standard lengths and diameters based on your drawings.
🏅 Triple ISO + CE Certified: ISO 9001 Quality, ISO 45001 Safety, and ISO 14001 Environmental certification, plus CE marking for European market compliance.
🏭 32,260 sqm Facility: The largest fastener manufacturing complex in the Middle East, equipped with advanced CNC machinery and full in-house production capability.
🔬 In-House Testing Lab: Full material traceability from raw stock to finished product. Tensile, hardness, dimensional, and spectroscopic testing all performed on-site.
🚚 Global Delivery: Shipped to 70+ countries via established logistics networks. Flexible packaging, documentation and third-party inspection support available.
