316L Low-Carbon Molybdenum Stainless Steel Coil Tube — Corrosion-Resistant Austenitic Grade
Product Overview
The 316L Low-Carbon Molybdenum Stainless Steel Coil Tube (Product No. 5) is a premium-grade austenitic stainless steel tubing supplied in continuous coil form by Wenzhou Jixing Metal Materials Co., Ltd. Engineered under the austenitic corrosion-resistant classification, this coil tube combines the inherent ductility and weldability of austenitic stainless steels with the exceptional resistance to pitting, crevice corrosion, and intergranular corrosion conferred by its unique low-carbon and molybdenum-enhanced chemistry.
Designed for the most demanding industrial environments, the 316L coil tube is the preferred material choice for pharmaceutical, food and beverage processing, seawater desalination, and ultra-pure water piping systems where material integrity, hygiene compliance, and long-term corrosion resistance are non-negotiable.
Key Differentiator: The synergistic combination of ultra-low carbon content (≤0.03% C) and molybdenum addition (2.0–2.5% Mo) provides simultaneous protection against pitting corrosion and intergranular sensitization — a dual defense mechanism unmatched by standard 304 or 316 grades in high-chloride and high-temperature welding applications.
Material & Properties
Chemical Composition (ASTM A213 / EN 10216-5)
| Element | Specification Range (%) | Typical Value (%) |
|---|---|---|
| Carbon (C) | ≤ 0.030 | ≤ 0.020 |
| Manganese (Mn) | ≤ 2.00 | ≤ 1.50 |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.030 |
| Sulfur (S) | ≤ 0.030 | ≤ 0.015 |
| Silicon (Si) | ≤ 1.00 | ≤ 0.75 |
| Chromium (Cr) | 16.00 – 18.00 | 17.00 |
| Nickel (Ni) | 10.00 – 14.00 | 12.50 |
| Molybdenum (Mo) | 2.00 – 2.50 | 2.20 |
| Nitrogen (N) | — | ≤ 0.10 |
| Iron (Fe) | Balance | Balance |
Mechanical Properties (Annealed Condition, ASTM A213)
| Property | Requirement |
|---|---|
| Tensile Strength | ≥ 485 MPa (≥ 70,000 psi) |
| Yield Strength (0.2% Offset) | ≥ 170 MPa (≥ 24,700 psi) |
| Elongation (50 mm gauge length) | ≥ 40% |
| Hardness (Brinell) | ≤ 217 HB |
| Thermal Conductivity (20°C) | 14.6 W/(m·K) |
| Specific Heat (20°C) | 500 J/(kg·K) |
| Linear Expansion (20–100°C) | 17.2 × 10⁻⁶ /°C |
| Maximum Service Temperature | 870°C (1,598°F) |
Corrosion Resistance Profile
- Pitting Resistance: Molybdenum content elevates the pitting resistance equivalent number (PREN) to approximately 24–26, providing superior resistance in chloride-containing environments compared to 304L (PREN ~18–19).
- Intergranular Corrosion Resistance: Carbon content reduced to ≤0.03% eliminates chromium carbide precipitation at grain boundaries during welding and heat treatment, preventing sensitization even in the 450–850°C range.
- Crevice Corrosion Resistance: Enhanced by the Mo addition, the material maintains passive film integrity in tight geometries and under deposits where oxygen is depleted.
- General Corrosion Resistance: Effective in dilute sulfuric, phosphoric, and citric acids, as well as neutral and mildly alkaline solutions at ambient to moderate temperatures.
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Material Grade | 316L (UNS S31603 / 1.4404 / 0Cr17Ni12Mo2) |
| Classification | Austenitic — Corrosion-Resistant Type |
| Manufacturing Method | Seamless / Welded (per customer requirement) |
| Outer Diameter (OD) | 6.00 – 50.80 mm (0.236 – 2.000 in) |
| Wall Thickness | 0.50 – 3.00 mm (0.020 – 0.118 in) |
| Coil Length | Up to 1,000 m per coil (custom lengths available) |
| Surface Finish | Pickled & Passivated (2B), Bright Annealed (BA), or Polished |
| Surface Roughness (Ra) | ≤ 0.8 μm (BA finish); ≤ 0.4 μm (electropolished, on request) |
| Delivery Condition | Annealed (Solution Annealed), Soft Annealed |
| Applicable Standards | ASTM A213/A213M, ASME SA-213, EN 10216-5, GB/T 14976, JIS G3459 |
| Coil Packaging | Wooden pallet with moisture-proof wrapping and export-grade steel banding |
| Minimum Order Quantity | 1,000 kg per grade (negotiable) |
Manufacturing Process
The production of 316L stainless steel coil tube at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorously controlled multi-stage process ensuring metallurgical purity, dimensional accuracy, and surface integrity:
- Raw Material Selection: Virgin 316L stainless steel billets or strip are sourced from certified mills with full chemical traceability. Incoming materials undergo spectroscopic analysis to verify compliance with ASTM A213 chemical requirements.
- Hot Rolling / Extrusion: Billets are hot-rolled or extruded to form seamless tube blanks at temperatures between 1,150°C and 1,250°C. For welded variants, precision cold-rolled strip is used as the base material.
- Piercing and Sizing (Seamless): The hot tube blanks are pierced and subsequently hot-finished to achieve the target outer diameter and wall thickness with tight tolerances.
- Cold Drawing / Reduction: Tubes undergo multiple passes of cold drawing through precision tungsten carbide dies to achieve the final dimensions within ±0.05 mm tolerance. This process also improves surface finish and mechanical properties.
- Welding (Welded Variant): For welded coil tube, high-frequency induction welding (HF-IW) or orbital TIG welding is employed. The weld zone is subsequently ground and inspected to ensure full penetration and minimum weld residual stress.
- Solution Annealing: Tubes are heat-treated at 1,050–1,100°C followed by rapid water quenching. This dissolves any precipitated carbides and restores full austenitic microstructure, ensuring maximum corrosion resistance and ductility.
- Pickling and Passivation: Annealed tubes are pickled in a controlled mixed acid bath (HNO₃/HF) to remove oxide scale, followed by passivation in dilute nitric acid to restore the protective chromium oxide film.
- Coiling: The finished tube is coiled at controlled tension and speed to prevent surface scratches, deformation, or stress marks. Each coil is wound on a precision mandrel with protective paper or plastic film between layers.
- Final Inspection: Every coil undergoes 100% dimensional verification (OD, wall thickness, straightness), surface inspection, and non-destructive testing (eddy current or hydrostatic test) prior to packaging.
Applications
The 316L coil tube is specifically engineered for applications where both corrosion resistance and hygienic performance are critical:
Pharmaceutical Industry
- CIP (Clean-in-Place) and SIP (Sterilize-in-Place) piping systems
- Process fluid transfer lines for active pharmaceutical ingredients (APIs)
- WFI (Water for Injection) and purified water distribution systems
- Vacuum lines and compressed air manifolds in aseptic manufacturing
Food and Beverage Processing
- Milk, juice, and beer processing lines requiring sanitary-grade tubing
- CIP acid circulation systems (citric acid, nitric acid cleaning)
- Steam lines and condensate return systems
- Wine and distillation equipment piping
Seawater Desalination
- Feed water piping and brine handling systems in reverse osmosis (RO) plants
- Multi-stage flash (MSF) and multi-effect distillation (MED) plant tubing
- Coastal facility piping exposed to high-chloride marine atmospheres
Ultra-Pure Water Systems
- Semi-conductor manufacturing ultra-pure water (UPW) distribution loops
- Electroplating and chemical processing systems
- Laboratory instrumentation and analytical equipment tubing
Additional Applications
- Chemical processing plants handling mildly corrosive media
- Marine and offshore engineering (subsea equipment, ballast systems)
- Medical device manufacturing (endoscopes, surgical instrument tubing)
- Environmental protection equipment (wastewater treatment, flue gas desulfurization)
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications and complies with the following standards for 316L coil tube production:
- ISO 9001:2015 — Quality Management System certification covering all production and supply chain processes
- ISO 14001:2015 — Environmental Management System ensuring environmentally responsible manufacturing
- CE Marking — Compliance with European directives for pressure equipment and construction products
- EN 10204 3.1 — Third-party certified material test documentation provided with each shipment
- ASTM / ASME Compliance — Full conformance to ASTM A213/A213M and ASME SA-213 material and testing requirements
- GB/T 14976 — Chinese national standard compliance for seamless and welded stainless steel tubes
- NACE MR0175 / ISO 15156 — Available upon request for sour service applications
- 3-A Sanitary Standards — Surface finish and construction suitable for food-grade applications
- REACH & RoHS Compliance — Documentation available confirming restricted substance compliance for EU market access
Each coil is accompanied by a mill test certificate (MTC) including full chemical analysis (spectrographic), mechanical test results, heat treatment record, and dimensional inspection report, traceable to the specific heat number and production lot.
Unique Selling Points
- Dual Protection Chemistry: The 316L grade uniquely combines ultra-low carbon (≤0.03%) for intergranular corrosion resistance with molybdenum (2.0–2.5%) for pitting resistance — eliminating the need for post-weld heat treatment in sensitization-prone applications.
- Coil Form Factor Advantage: Continuous coil supply eliminates butt-weld joints, reducing potential leak points by up to 90% compared to straight-length pipe in long-run installations, thereby improving system integrity and reducing maintenance costs.
- Hygienic Surface Quality: BA and electropolished finishes achieve surface roughness values of Ra ≤ 0.4 μm, meeting FDA and 3-A sanitary requirements without additional post-installation polishing.
- Full Traceability: Every coil is laser-marked with grade, heat number, and lot identifier, enabling complete supply chain traceability from raw material to final installation.
- Customization Capability: Wenzhou Jixing offers flexible customization of OD, wall thickness, coil length, surface finish, and packaging configuration to meet specific project requirements.
- Cost-Effective Alternative to Duplex: For many chloride-containing applications where duplex 2205 would be over-specified, 316L provides adequate corrosion resistance at a significantly lower material cost and with superior weldability.
Technical Support & Ordering
Wenzhou Jixing Metal Materials Co., Ltd provides comprehensive technical support including material selection guidance, application engineering consultation, and post-delivery quality assurance. For detailed quotations, sample requests, or custom specifications, contact our sales engineering team with your project requirements including target dimensions, quantity, surface finish, and applicable standards.