Precision Seamless Stainless Steel Coil Tube — Sanitary Grade (GB/T 3639)
Product Overview
The Precision Seamless Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a high-precision, sanitary-grade tubing product designed to meet the rigorous requirements of GB/T 3639 (Precision Seamless Steel Tubes). Supplied in continuous coil form, this product combines exceptional dimensional accuracy with superior surface finish and cleanliness, making it ideal for applications demanding strict hygienic standards.
Unlike conventional cut-length tubing, coil tubes are delivered in continuous lengths, enabling customers to minimize waste, reduce welding joints, and optimize fabrication efficiency. The seamless construction ensures uniform material integrity throughout the tube wall, eliminating the potential contamination risks associated with welded seams.
Unique Selling Points
- Sanitary-Grade Surface Quality: Precision cold-drawn and polished to achieve mirror-like internal and external surfaces, minimizing product retention and facilitating thorough cleaning and sterilization.
- Continuous Coil Supply: Eliminates the need for butt-welding between tube segments, reducing contamination points and improving production throughput.
- Tight Dimensional Tolerances: Manufactured to meet the stringent tolerance requirements of GB/T 3639, ensuring interchangeability and compatibility with precision fittings and automated assembly systems.
- Seamless Construction: Guarantees metallurgical homogeneity, superior corrosion resistance, and structural integrity compared to welded alternatives.
- High Cleanliness Standards: Controlled manufacturing environment with rigorous decontamination protocols to meet pharmaceutical and food-grade requirements.
Material & Properties
Available Grades
- 304 / 304L (06Cr19Ni10 / 022Cr19Ni10): The most widely specified grade for general sanitary applications, offering excellent corrosion resistance, formability, and weldability.
- 316 / 316L (06Cr17Ni12Mo2 / 022Cr17Ni12Mo2): Enhanced molybdenum content provides superior resistance to pitting and crevice corrosion in aggressive chemical environments.
- 321 (06Cr18Ni11Ti): Titanium-stabilized grade suitable for elevated-temperature applications where sensitization resistance is critical.
- 904L (00Cr20Ni25Mo4Si2): High-alloy grade for extreme corrosion environments including strong oxidizing acids.
Key Mechanical Properties (304L Reference)
| Property | Specification |
|---|---|
| Tensile Strength | ≥ 520 MPa (75,400 psi) |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (29,700 psi) |
| Elongation | ≥ 40% |
| Hardness (HV) | ≤ 220 |
| Density | 7.93 g/cm³ (0.285 lb/in³) |
| Thermal Conductivity (20°C) | 16.3 W/(m·K) (9.4 BTU/hr·ft·°F) |
| Maximum Service Temperature | 870°C (1,598°F) |
Surface Finish Options
- Electropolished (EP): Ra ≤ 0.25 µm (0.010 µin) — recommended for pharmaceutical, biotech, and dairy applications.
- Passivated: Chemical passivation treatment to maximize natural chromium oxide protective layer.
- Polished (Internal/External): Ra ≤ 0.4 µm (0.016 µin) — suitable for food processing and beverage applications.
Specifications
| Parameter | Specification |
|---|---|
| Governing Standard | GB/T 3639 (Precision Seamless Steel Tubes) |
| Classification | Chinese National Standard — Sanitary Grade |
| Outer Diameter (OD) | Φ6.0 – Φ114.3 mm (0.236" – 4.500") |
| Wall Thickness | 0.30 – 6.0 mm (0.012" – 0.236") |
| OD Tolerance | ±0.05 mm (±0.002") |
| Wall Thickness Tolerance | ±0.03 mm (±0.001") |
| Roundness | ≤ 0.05 mm (0.002") |
| Coil Inner Diameter | Φ150 mm / Φ300 mm (5.91" / 11.81") |
| Coil Length | Custom (typically 50 – 300 m / 164 – 984 ft per coil) |
| End Condition | Open / Closed / Beveled |
| Heat Treatment | Solution Annealed + Water Quenched |
| Packaging | Wooden crate or export-grade steel drum with moisture barrier |
Manufacturing Process
- Raw Material Selection: Virgin or certified remelt stainless steel billets/slabs from reputable mills, with full chemical composition verification via spectroscopic analysis.
- Hot Rolling: Billets are heated to forging temperature (1,100–1,200°C / 2,012–2,192°F) and pierced through a mandrel to produce seamless hot-rolled tubes.
- Solution Annealing: Tubes are reheated to 1,050–1,100°C (1,922–2,012°F) and rapidly water-quenched to achieve a uniform austenitic microstructure and relieve residual stresses.
- Pickling & Descaling: Removal of oxide scale through controlled acid pickling to expose the clean metallic surface.
- Cold Drawing: Tubes are drawn through precision dies to achieve final OD, wall thickness, and tight dimensional tolerances in accordance with GB/T 3639.
- Intermediate Annealing: Periodic solution annealing during multi-pass drawing to restore ductility and prevent work-hardening fracture.
- Precision Polishing: Internal and external surfaces are polished using multi-stage abrasive processes to achieve the required Ra values for sanitary service.
- Electropolishing (Optional): Electrochemical dissolution of surface irregularities to achieve Ra ≤ 0.25 µm with enhanced corrosion resistance.
- Passivation: Final chemical passivation using nitric or citric acid solutions to form a protective chromium oxide film.
- Cleaning & Inspection: Ultrasonic testing for wall thickness verification, visual inspection, dimensional measurement, and cleanliness assessment.
- Coiling & Packaging: Tubes are coiled onto precision mandrels, wrapped with protective film, and secured in export-grade packaging.
Applications
- Pharmaceutical & Biotechnology: Process piping, CIP (Clean-In-Place) systems, fermentation tanks, and hygienic transfer lines requiring 3-A Sanitary Standards compliance.
- Food & Beverage Processing: Dairy processing equipment, brewing systems, juice and wine production lines, and hygienic pump housings.
- Medical Devices: Surgical instrument tubing, dialysis equipment, and implant manufacturing feedstock.
- Chemical Processing: Reactor internals, heat exchanger tubes, and corrosive fluid transfer systems.
- Electronics & Semiconductor: Ultra-pure fluid delivery systems and vacuum components requiring high purity and tight tolerances.
- Automotive & Aerospace: Precision fuel lines, hydraulic tubing, and structural components requiring high strength-to-weight ratios.
Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| GB/T 3639 | Chinese National Standard for Precision Seamless Steel Tubes — primary governing specification |
| ISO 9001:2015 | Quality Management System certification ensuring consistent production quality |
| ISO 14001 | Environmental Management System certification |
| ASME BPE (Compatible) | Bioprocessing Equipment standards for surface finish and cleanliness |
| 3-A Sanitary Standards | Dairy and food processing sanitary design and construction compliance |
| CE Marking | European Conformity for market access in EEA |
| EN 10217-7 | European standard for cold-drawn seamless stainless steel tubes (equivalent reference) |
| ASTM A213 / A269 | American material specification equivalence available upon request |
Quality Assurance Measures
Every coil of precision seamless stainless steel tube undergoes comprehensive quality verification prior to shipment. This includes 100% ultrasonic wall thickness testing, spectrometric chemical analysis, dimensional verification at multiple intervals, visual surface inspection under controlled lighting, and cleanliness assessment per ISO 14644 protocols. Full material traceability is maintained from mill heat number through final coil identification, with mill test certificates (MTC) provided per EN 10204 Type 3.1 upon request.
Testing & Inspection Capabilities
- 100% ultrasonic thickness testing (UT) along the tube length
- Chemical composition analysis via optical emission spectrometry (OES)
- Hydrostatic or pneumatic pressure testing at 2× working pressure
- Surface roughness measurement (Ra) at multiple locations
- Hardness testing (Vickers) per sampling plan
- Tensile testing of sample coupons per lot
- Intergranular corrosion testing (ASTM A923 Method 1A) for stabilized grades
- Visual and dimensional inspection per GB/T 3639 acceptance criteria
Technical Support & Customization
Wenzhou Jixing Metal Materials Co., Ltd. offers comprehensive technical support including:
- Custom OD and wall thickness combinations outside standard ranges
- Special surface finish specifications tailored to customer requirements
- Coil length optimization based on customer consumption rates
- End preparation services (beveling, capping, plug welding)
- Technical consultation on material selection and design validation
- Sample provision for customer qualification and testing
For detailed quotations, sample requests, or technical inquiries regarding our Precision Seamless Stainless Steel Coil Tube product line conforming to GB/T 3639 sanitary grade standards, please contact our engineering team for personalized solutions tailored to your specific application requirements.