316L EP Coil Tube for Chromatography & Ultrafiltration Systems
Wenzhou Jixing Metal Materials Co., Ltd presents a premium-grade 316L Electropolished (EP) stainless steel coil tube specifically engineered for biopharmaceutical chromatography and ultrafiltration process piping systems. This product is purpose-built to meet the stringent requirements of modern biologics manufacturing, where buffer compatibility across extreme pH ranges, minimal protein adsorption, and electrical conductivity integrity are non-negotiable performance criteria.
Product Overview
The 316L EP Coil Tube is designed as a dedicated process fluid conduit for chromatography columns, ultrafiltration/diafiltration (UF/DF) systems, and associated buffer delivery circuits within biopharmaceutical production lines. Unlike standard sanitary tubing, this coil tube undergoes a specialized electropolishing process that produces an ultra-smooth, passivated inner surface with exceptionally low protein adsorption characteristics — a critical requirement when handling sensitive protein therapeutics, monoclonal antibodies, and biologics at various stages of purification.
Engineered to withstand aggressive buffer solutions spanning pH 2 through pH 12, this coil tube ensures long-term chemical stability, corrosion resistance, and product purity without introducing metallic ion contamination or catalyzing protein denaturation. The coil configuration offers superior flexibility during system installation, reduces the number of fittings and welds required, and minimizes dead volume — all essential for maintaining process integrity and reducing cleaning validation complexity.
Material & Properties
- Base Material: ASTM A270 / EN 10217-7 grade 316L stainless steel (low-carbon variant with <0.03% carbon to prevent intergranular corrosion during welding)
- Chromium Content: 16.5–18.5% — provides baseline corrosion resistance and passive film formation
- Nickel Content: 10.0–14.0% — enhances ductility and resistance to pitting in chloride-containing environments
- Molybdenum Content: 2.0–3.0% — critical for resistance to chlorinated buffer solutions and reducing agents commonly used in chromatography
- Carbon Content: <0.03% — eliminates sensitization risk at elevated process temperatures
- Electropolished Surface Finish: Inner surface Ra ≤ 0.4 μm (16 μin), delivering a protein-adsorption-resistant, non-catalytic surface
- Passivation: Nitric acid or citric acid passivation per ASTM A967 / ASTM A380
Key Performance Advantages
- Full pH Range Compatibility (pH 2–12): Seamlessly handles acidic ion-exchange buffers (e.g., HCl, H₃PO₄ at pH 2–3), neutral buffers (e.g., PBS, Tris at pH 6.5–7.5), and alkaline buffers (e.g., NaOH, arginine at pH 10–12) without material degradation, leaching, or surface attack.
- Ultra-Low Protein Adsorption Surface: The electropolished inner surface minimizes protein binding and biofilm formation, preserving product yield, reducing carryover risk between batches, and facilitating CIP (Clean-in-Place) protocols.
- Electrical Conductivity Compatibility: The passivated, low-contamination surface does not interfere with in-line conductivity sensors or resistivity measurements — essential for buffer exchange monitoring and process analytical technology (PAT) in chromatography systems.
- Coil Form Factor: Reduces installation labor, minimizes the number of sanitary fittings and weld joints, decreases potential contamination points, and allows flexible routing in compact bioprocess skid configurations.
Specifications
| Parameter | Specification |
|---|---|
| Material Grade | 316L (UNS S31603 / 1.4404) |
| Product Form | Coil Tube (continuous coil delivery) |
| Surface Treatment | Electropolished (EP), Ra ≤ 0.4 μm (16 μin) inner surface |
| Applicable pH Range | 2 – 12 (acidic, neutral, and alkaline buffers) |
| Protein Adsorption | Ultra-low (EP passivated surface) |
| Conductivity Compatibility | Yes — no interference with in-line conductivity/resistivity monitoring |
| Maximum Operating Temperature | Up to 260°C (500°F) continuous |
| Available Outer Diameters | 3/8" (Ø9.5 mm) to 4" (Ø102 mm) — custom sizes available |
| Wall Thickness | 0.5 mm – 3.0 mm (customizable per application) |
| Coil Length per Spool | 10 m – 100 m (standard); custom lengths upon request |
| End Condition | Plain cut, beveled, or with sanitary fittings (Tri-Clamp, VCR, Swagelok, etc.) |
| Standard Compliance | ASTM A270, ASME BPE, EN 10217-7, DIN 11850, 3-A Sanitary Standards |
| Welding Suitability | Orbital TIG welding compatible (low-carbon 316L prevents sensitization) |
Manufacturing Process
The production of this 316L EP Coil Tube follows a rigorously controlled multi-stage manufacturing sequence:
- Raw Material Sourcing: Virgin 316L stainless steel bar stock from certified mills with full mill test reports (MTR) verifying chemical composition and mechanical properties per ASTM A270 / EN 10217-7.
- Piercing & Drawing: Hot-pierced billets are cold-drawn through precision tungsten carbide dies to achieve exact dimensional tolerances and consistent wall thickness throughout the coil length.
- Heat Treatment: Solution annealing at 1050–1100°C followed by controlled water quenching to ensure full austenitic microstructure and maximum corrosion resistance.
- Electropolishing: The tube interior is electropolished using a controlled DC electrolytic process that removes surface imperfections, eliminates cold-work hardening, and produces a uniform, smooth, passivated surface with Ra ≤ 0.4 μm. This step is critical for achieving low protein adsorption and conductivity compatibility.
- Acid Passivation: Post-EP passivation treatment per ASTM A967 to form a stable chromium oxide passive film that further enhances corrosion resistance and surface inertness.
- Coiling: The finished tube is coiled on precision mandrels to specified coil diameters, ensuring uniform bend radius and freedom from kinks or distortions.
- End Finishing & Fitting Installation: Tube ends are cut, beveled, or fitted with sanitary-grade connectors (Tri-Clamp, VCR, or equivalent) as specified by the end user.
- Final Inspection & Packaging: Each coil undergoes dimensional verification, surface roughness measurement, visual inspection, and optional borescope examination. Tubes are packaged in protective plastic wraps and wooden crates with accompanying material traceability documentation.
Applications
- Chromatography Systems: Buffer supply lines, column inlet/outlet connections, and post-column tubing for ion-exchange (IEC), size-exclusion (SEC), hydrophobic interaction (HIC), and affinity chromatography in biologics purification.
- Ultrafiltration/Diafiltration (UF/DF) Systems: Feed lines, permeate lines, and concentrate recirculation loops in tangential flow filtration (TFF) processes for protein concentration, buffer exchange, and desalting.
- Bioreactor Loop Piping: Process fluid transfer lines connecting bioreactors to downstream purification skids, where protein-sensitive, pH-variable media are handled.
- WFI/Process Water Lines: Suitable for pharmaceutical-grade water distribution circuits requiring low leachables and conductivity monitoring compatibility.
- Cell Culture Media Delivery: Gentle, non-adsorptive transport of growth media, supplements, and inducers in upstream processing.
- Gene Therapy & mRNA Production: Pipelines handling sensitive nucleic acid and lipid nanoparticle formulations requiring ultra-clean, low-adsorption surfaces.
Quality Certifications & Compliance
- Material Certification: Full EN 10204 3.1 mill test certificates for every batch, with chemical analysis and mechanical property verification.
- Surface Quality: Electropolished inner surface verified by surface roughness measurement (Ra ≤ 0.4 μm) and borescope inspection reports.
- Standards Compliance: ASTM A270, ASME BPE (Bioprocessing Equipment), EN 10217-7, DIN 11850, 3-A Sanitary Standards.
- Pharmaceutical Suitability: 316L grade with low carbon content meets FDA 21 CFR requirements for pharmaceutical contact materials; compatible with USP <665> and <661> leachable/extractable testing protocols.
- ISO Standards: Manufacturing facility operates under ISO 9001 quality management systems; product specifications aligned with ISO 15001 (hygienic design).
- Traceability: Full material lot traceability from mill certification through final delivery, supporting GMP audit requirements.
Why Choose Wenzhou Jixing Metal Materials Co., Ltd? With deep expertise in bioprocess-grade stainless steel tubing, Wenzhou Jixing delivers 316L EP coil tubes that combine exceptional corrosion resistance across the full pH 2–12 range, ultra-low protein adsorption surfaces, and verified conductivity compatibility — all in a flexible coil form that simplifies installation and reduces contamination risk in chromatography and ultrafiltration systems.