Sanitary Stainless Steel Coil Tube — ASTM A270
Product Overview
The Sanitary Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a premium-grade tubular product designed and fabricated in strict accordance with ASTM A270 — the American standard for Sanitary Tubing and Pipe for Instrumentation, Food Processing, and Chemical Service. This product line encompasses both seamless and welded coil tubes engineered specifically for hygienic, food-grade, pharmaceutical, and chemical processing environments where surface integrity, corrosion resistance, and cleanliness are paramount.
As a coil tube product, the sanitary stainless steel tubing is supplied in continuous coiled form, offering significant advantages in downstream fabrication including reduced waste, lower labor costs, and enhanced production efficiency for tube bending, cutting, and forming operations.
Material & Properties
The sanitary coil tubes are manufactured from high-purity austenitic stainless steel grades, most commonly 304 (UNS S30400) and 316L (UNS S31603), selected for their exceptional resistance to intergranular corrosion, pitting, and crevice attack under aggressive chemical and biological environments.
- Chemical Composition: Carbon content is tightly controlled (≤0.08% for 304; ≤0.03% for 316L) to ensure resistance to sensitization during welding and heat treatment processes.
- Mechanical Properties: Tensile strength of ≥515 MPa (75,000 psi) with elongation ≥40%, ensuring adequate formability for cold working operations including coiling, bending, and deep drawing.
- Corrosion Resistance: The high chromium (≥18%) and nickel (≥8%) content provides a robust passive oxide layer, with 316L additionally containing 2–3% molybdenum for enhanced chloride resistance.
- Hygienic Surface Finish: Inner surface roughness (Ra) is maintained at ≤0.5 μm (20 μin) for standard sanitary applications, with electropolished variants achieving Ra ≤0.25 μm (10 μin) for critical pharmaceutical and bioprocessing use.
Specifications
| Parameter | Specification |
|---|---|
| Governing Standard | ASTM A270 / A270M |
| Product Form | Coil Tube (Continuous Coiled Length) |
| Manufacturing Method | Seamless & Welded (ERW / Orbital TIG) |
| Applicable Grades | 304, 304L, 316, 316L, 321, 310S |
| Outside Diameter (OD) | 1/8" (3.18 mm) – 6" (152.4 mm) |
| Wall Thickness | 0.4 mm – 12.7 mm (Schedule 5S through 80S) |
| Inner Surface Roughness (Ra) | ≤0.5 μm (Standard); ≤0.25 μm (Electropolished) |
| Outer Surface Finish | Mirror Polished (Ra ≤0.4 μm) or Brushed |
| Weld Finish | Ground & Polished Flush; No Visible Weld Line |
| Passivation Treatment | Citric Acid or Nitric Acid Passivation per ASTM A967 |
| Coil Inner Diameter | 300 mm – 1,200 mm (Customizable) |
| Coil Weight | Up to 2,500 kg per coil |
| End Condition | Plain End, Beveled, or Custom Trimmed |
| Heat Treatment | Solution Annealed & Pickled (SAP) |
| Packaging | Wooden Pallet with Moisture-Proof Film Wrapping |
Manufacturing Process
The production of sanitary stainless steel coil tubes follows a rigorous, multi-stage manufacturing protocol designed to ensure dimensional accuracy, surface integrity, and hygienic compliance throughout the entire process chain:
- Raw Material Selection: Virgin or certified remelt stainless steel billets or strip are sourced with full chemical composition traceability, verified through spectroscopic analysis (OES) and certified mill test reports.
- Seamless Production (Ring Rolling & Extrusion): For seamless coil tubes, hot-rolled rings or extruded billets are cold-drawn through precision dies to achieve the target OD and wall thickness with tight tolerances (±0.05 mm).
- Welded Production (ERW / Orbital TIG): Precision cold-rolled strip is fed through resistance welding (ERW) or orbital TIG welding equipment with inert gas (argon) shielding to produce a continuous, defect-free weld seam.
- Weld Seam Grinding & Polishing: The internal weld seam is mechanically ground and progressively polished using diamond and alumina abrasives to achieve a flush, smooth surface with Ra ≤0.5 μm, eliminating potential bacterial harborage points.
- Acid Pickling & Passivation: The tube is subjected to citric acid or nitric acid pickling to remove scale, oxide, and decarburized layers. A subsequent passivation treatment per ASTM A967 ensures a uniform, chromium-rich passive film for maximum corrosion resistance.
- Electropolishing (Optional): For ultra-clean applications, the tube undergoes electrochemical polishing to achieve Ra ≤0.25 μm with a pore-free, microscopically smooth interior surface.
- Dimensional Inspection & Testing: Each coil undergoes 100% visual inspection, ultrasonic testing (UT) for wall thickness verification, hydrostatic pressure testing (per ASTM A270, Section 7), and surface roughness profiling (laser-based profilometry).
- Coiling & Packaging: The finished tube is coiled onto precision steel mandrels, secured with stainless steel straps, wrapped in moisture-barrier film, and palletized for shipment.
Key Performance Highlights & Unique Selling Points
- ASTM A270 Full Compliance: Complete adherence to the American standard for sanitary tubing ensures acceptance in regulated industries worldwide, including FDA, USDA, and EU pharmaceutical compliance frameworks.
- Superior Surface Integrity: Inner surface Ra values of ≤0.5 μm (standard) or ≤0.25 μm (electropolished) significantly reduce biofilm formation risk and facilitate automated CIP (Clean-In-Place) and SIP (Sterilize-In-Place) operations.
- Flush Weld Finish: Ground and polished weld seams eliminate dead legs and crevices where microbial contamination could accumulate, critical for GMP (Good Manufacturing Practice) environments.
- Coil Form Efficiency: Continuous coil supply reduces cutting waste by up to 95% compared to cut-length tubing, lowering total cost of ownership for high-volume fabrication.
- ASTM A967 Passivation: Verified passivation treatment guarantees long-term corrosion resistance and surface stability in aggressive chemical environments.
- Full Traceability: Each coil is accompanied by a Certificate of Conformance (CoC), mill test reports, and heat number traceability documentation.
Applications
Sanitary stainless steel coil tubes conforming to ASTM A270 are indispensable in the following industrial sectors:
- Food & Beverage Processing: Dairy processing, brewing, juice and soft drink production, meat processing, and confectionery equipment where hygienic fluid transfer is required.
- Pharmaceutical & Biotechnology: Bioreactor piping, CIP/SIP systems, pharmaceutical water systems (WFI, PW), and cleanroom fluid conveyance under GMP conditions.
- Chemical & Petrochemical: Corrosive chemical transfer lines, reactor internals, and process instrumentation tubing.
- Medical Devices: Tubing for medical gas delivery, dialysis systems, and hospital fluid distribution networks.
- Beer & Beverage Equipment Manufacturing: Brewing process piping, fermentation tank connections, and packaging line fluid conveyance.
- Semiconductor & Electronics: Ultra-pure chemical delivery systems and wafer processing fluid lines.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that every coil tube product meets or exceeds international standards:
| Certification / Standard | Description |
|---|---|
| ASTM A270 / A270M | Sanitary Tubing and Pipe — Primary Product Standard |
| ASTM A967 | Chemical Passivation of Stainless Steel Parts |
| ISO 9001:2015 | Quality Management System Certification |
| ISO 14283 | Hygienic Design of Food Equipment — Surface Requirements |
| 3-A Sanitary Standards | American Dairy Sanitary Standards Compliance |
| EHEDG | European Hygienic Engineering & Design Group Compliance |
| NSF / ANSI 61 | Drinking Water System Components — Health Effects |
| CE Marking | European Conformity for Pressure Equipment (PED 2014/68/EU) |
| MTC / EN 10204 3.1 | Material Test Certificate — Third-Party Inspected |
Quality Assurance Commitment: Every production lot undergoes 100% hydrostatic pressure testing, visual surface inspection, dimensional verification, and chemical passivation verification. Optional third-party inspection by SGS, Bureau Veritas, or TÜV is available upon customer request.