316L Stainless Steel Coil Tube — Mo-Containing Austenitic Grade for Cost-Optimized Procurement
Product Overview
The 316L Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered, cold-worked austenitic stainless steel tubing supplied in coil form. This product is engineered around the critical alloying element Molybdenum (Mo), which constitutes approximately 15%–20% of the total material cost in 316L-grade tubing. The coil format offers superior formability, reduced waste during downstream fabrication, and enhanced production efficiency for end-users across chemical processing, pharmaceutical, food-grade, and marine engineering sectors.
Given the inherent volatility of global molybdenum commodity pricing, this product line incorporates a flexible pricing mechanism designed to protect both supplier and buyer against market disruptions. When molybdenum price fluctuations exceed defined thresholds, the price-lock cycle is shortened accordingly to ensure cost transparency and supply continuity.
Material & Properties
The 316L grade is a low-carbon variant of 316 austenitic stainless steel, distinguished by its elevated molybdenum content (2.0%–3.0% by weight), which provides exceptional resistance to pitting and crevice corrosion, particularly in chloride-containing environments.
- Microstructure: Fully austenitic (face-centered cubic, FCC), non-magnetic in the annealed condition
- Carbon Content: ≤ 0.03% (reduced to prevent intergranular corrosion during welding)
- Molybdenum (Mo) Contribution: 2.0%–3.0% — responsible for ~15%–20% of total material cost; primary driver of enhanced corrosion resistance in aggressive media
- Chromium (Cr): 16.0%–18.0% — provides passive oxide layer formation
- Nickel (Ni): 10.0%–14.0% — stabilizes austenitic structure
- Corrosion Resistance: Superior to 304L in sulfuric acid, phosphoric acid, and seawater environments
- Temperature Range: Continuous service from cryogenic temperatures (−196°C) up to 870°C (non-load-bearing)
Specifications
| Parameter | Specification / Range |
|---|---|
| Material Grade | SUS 316L / ASTM 316L / UNS S31603 |
| Mo Content (wt%) | 2.0% – 3.0% |
| Mo Cost Share | 15% – 20% of total material cost |
| Outer Diameter (OD) | Φ6.0 mm – Φ159.0 mm |
| Wall Thickness | 0.3 mm – 6.0 mm |
| Coil Length | Custom (typically 5 m – 50 m per coil) |
| Surface Finish | No.4 brushed / BA (Bright Annealed) / 2B / Polished (Ra ≤ 0.4 μm) |
| Tolerance (OD) | ±0.05 mm (precision grade) / ±0.10 mm (standard grade) |
| Tolerance (Wall) | ±10% of nominal |
| Standard | ASTM A269 / ASTM A270 / GB/T 12771 / EN 10217 |
| Heat Treatment | Solution annealed at 1010°C – 1120°C, followed by water quench |
| Price-Lock Cycle (Normal) | 30 – 60 days |
| Price-Lock Cycle (Mo Volatility >15%) | 7 – 15 days (shortened per contractual agreement) |
Manufacturing Process
- Raw Material Sourcing: Virgin stainless steel billets or wire rod are procured with certified Mo, Cr, and Ni compositions. Molybdenum ingots are sourced from multiple suppliers to mitigate single-source supply risk.
- Piercing & Extrusion: Billets are heated to 1200°C–1250°C and pierced to form seamless tube blanks.
- Rolling & Drawing: Multi-pass cold rolling and drawing operations achieve target OD and wall dimensions with tight tolerances.
- Intermediate Annealing: Periodic solution annealing during cold work prevents work hardening and maintains ductility.
- Final Annealing & Pickling: Tubes are solution-annealed at 1010°C–1120°C, water quenched, and subjected to acid pickling to restore full corrosion resistance and passive film integrity.
- Surface Finishing: Optional polishing, brushing, or bright annealing in controlled-atmosphere furnaces.
- Coiling & Packaging: Tubes are wound onto precision coils with protective inter-layer wrapping and moisture-barrier outer packaging.
- Quality Inspection: 100% ultrasonic testing (UT), hydrostatic pressure testing, dimensional verification, and spectroscopic chemical analysis (OES/ICP).
Applications
- Chemical Processing: Heat exchangers, reactor tubing, piping systems handling sulfuric acid, hydrofluoric acid, and other aggressive chemical media
- Pharmaceutical & Biotechnology: Sanitary-grade process tubing, CIP (Clean-In-Place) systems, fermentation vessel internals
- Food & Beverage Industry: Dairy processing lines, brewing equipment, food-grade transfer tubing
- Marine & Offshore: Seawater cooling circuits, desalination plant components, subsea instrumentation housings
- Energy Sector: Solar thermal collector tubes, fuel cell components, geothermal well casings
- Medical Devices: Endoscope tubing, implant-grade precision tubing (where applicable)
Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System
- ISO 14001 — Environmental Management System
- EN 10204 3.1 Certificate — Material test certificate per batch
- ASTM / ASME Compliance — Full conformance to American standards
- CE Marking — European conformity for pressure equipment (PED 2014/68/EU)
- Mill Test Reports (MTR) — Provided with every shipment, including chemical composition, mechanical properties, and heat treatment records
- NACE MR0175 / ISO 15156 — Available for sour service applications
Unique Selling Points
- Cost Transparency via Mo-Linked Pricing: A structured pricing framework that explicitly accounts for the 15%–20% molybdenum cost share, with dynamically adjustable price-lock cycles during periods of commodity volatility — reducing procurement risk for end-users.
- Coil Format Efficiency: Continuous coil supply eliminates butt-weld joints between tube segments, reducing material waste by up to 12% compared to straight-length delivery and enabling seamless automated forming operations.
- Multi-Grade Flexibility: Available in 316L, 316LMo (elevated Mo for extreme chloride environments), and custom-balanced compositions tailored to specific corrosion service conditions.
- Full Traceability: Each coil is serialized with complete metallurgical provenance, from raw ingot to finished product, enabling full supply chain auditability.
Procurement Note: Given that Molybdenum (Mo) represents 15%–20% of the total material cost for 316L stainless steel coil tube, buyers are advised to incorporate commodity-linked pricing clauses and shortened price-lock periods (7–15 days) when Mo market volatility exceeds ±15% quarter-over-quarter. Wenzhou Jixing Metal Materials Co., Ltd. provides monthly Mo price index updates to support informed procurement planning.