Hygienic-Grade Precision Seamless Stainless Steel Coil Tube — GB/T 3639
1. Product Overview
The Hygienic-Grade Precision Seamless Stainless Steel Coil Tube, manufactured by Wenzhou Jixing Metal Materials Co., Ltd, is a high-precision tubing product conforming to the Chinese National Standard GB/T 3639 (Precision Seamless Steel Tubes). Designed for the most demanding applications in the food, pharmaceutical, and biotechnology industries, this coil tube delivers exceptional dimensional accuracy, superior surface finish, and stringent cleanliness levels that meet hygienic processing requirements.
Unlike conventional stainless steel tubing, this product is specifically engineered to eliminate dead legs, minimize microbial harborage points, and ensure complete fluid transfer efficiency. The coil configuration provides logistical advantages including reduced cutting waste, simplified handling, and efficient downstream processing through automated forming and cutting equipment.
2. Material & Properties
The coil tube is fabricated from austenitic stainless steel grades selected for their corrosion resistance, weldability, and biocompatibility. The primary material grades include:
- 304 (06Cr19Ni10) — General-purpose hygienic applications with excellent corrosion resistance
- 316 (06Cr17Ni12Mo2) — Enhanced resistance to chlorides and aggressive chemical environments
- 316L (022Cr17Ni12Mo2) — Low-carbon variant for superior weldability in sanitary systems
Key Material Properties
| Property | Specification |
|---|---|
| Carbon (C) Maximum | 0.08% (304); 0.03% (316L) |
| Chromium (Cr) | 18.0–20.0% |
| Nickel (Ni) | 8.0–11.0% |
| Molybdenum (Mo) | 2.0–3.0% (316/316L) |
| Tensile Strength (Rm) | ≥ 520 MPa |
| Yield Strength (Rp0.2) | ≥ 205 MPa |
| Elongation (A50mm) | ≥ 40% |
| Surface Roughness (Ra) | ≤ 0.4 μm (electropolished); ≤ 0.8 μm (passivated) |
| Maximum Surface Defects | None exceeding 0.5 mm in any dimension |
3. Specifications
| Parameter | Specification / Range |
|---|---|
| Standard | GB/T 3639 (Precision Seamless Steel Tubes) |
| Outer Diameter (OD) | 6.0 mm – 108.0 mm |
| Wall Thickness (WT) | 0.5 mm – 4.0 mm |
| OD Tolerance | ± 0.05 mm (Precision Grade A) |
| Wall Thickness Tolerance | ± 0.02 mm (Precision Grade A) |
| Coil Length | 50 m – 300 m (continuous) |
| Coil Inner Diameter | 150 mm – 400 mm |
| Coil Weight | 50 kg – 500 kg per coil |
| Surface Treatment | Electropolished / Passivated / Mirror Polish |
| End Condition | Plain ends, deburred, or with protective caps |
| Hygienic Surface Quality | Free of pits, cracks, seams, or oxide inclusions |
| Cleanliness Grade | Class A — Free of residual oils, particulates, and contaminants |
4. Manufacturing Process
The production of hygienic-grade precision seamless coil tube follows a rigorously controlled multi-stage process to ensure compliance with GB/T 3639 dimensional tolerances and hygienic surface standards:
- Raw Material Selection & Inspection — Certified stainless steel ingots undergo spectroscopic analysis to verify chemical composition within specified grade limits.
- Hot Rolling & Annealing — Billet stock is hot-rolled to approximate dimensions and subsequently annealed to achieve a uniform austenitic microstructure.
- Precision Cold Drawing — Tubes are cold-drawn through precision-die systems to achieve the tight dimensional tolerances (± 0.05 mm OD, ± 0.02 mm WT) mandated by GB/T 3639.
- Pneumatic Expanding & Sizing — Internal surfaces are expanded using air-pressure die systems to eliminate internal burrs and ensure uniform wall thickness.
- Electrochemical Polishing (ECP) — The tube interior and exterior are subjected to electrochemical polishing to achieve a surface roughness of Ra ≤ 0.4 μm, removing micro-crevices where microorganisms could reside.
- Passivation Treatment — A controlled acid passivation process removes free iron and contaminants from the surface, forming a stable chromium oxide passive layer that enhances corrosion resistance.
- Cleanliness Processing — Tubes undergo ultrasonic cleaning in deionized water, followed by drying with filtered nitrogen, ensuring zero residual particulates or organic contamination.
- Coiling & Packaging — Finished tubing is coiled on precision mandrels, wrapped in protective film, and packed in hygienic-grade packaging to maintain cleanliness through storage and transit.
5. Applications
The hygienic-grade precision seamless coil tube is purpose-built for industries where product purity, process reliability, and regulatory compliance are paramount:
- Pharmaceutical Manufacturing — Transfer of sterile fluids, CIP (Clean-in-Place) and SIP (Sterilize-in-Place) systems, bioreactor connections, and clean steam lines compliant with GMP (Good Manufacturing Practice) standards.
- Food & Beverage Processing — Milk processing lines, beer brewing systems, juice transfer, dairy equipment, and bottling plant piping conforming to FDA and EU food-contact regulations.
- Biochemical & Biotechnology — Cell culture media transfer, fermentation systems, chromatography columns, and analytical instrument tubing requiring ultra-low particulate and extractable levels.
- Medical Devices — Tubing for dialysis equipment, medical gas systems, and implant manufacturing where biocompatibility and surface integrity are critical.
- Semiconductor & Ultra-Pure Fluid Systems — Ultra-pure water (UPW) distribution, chemical delivery systems, and high-purity gas lines requiring 18.2 MΩ·cm resistivity-grade fluid transfer.
- Cosmetics & Personal Care — Transfer of active ingredients, emulsions, and finished products in production lines requiring hygienic processing conditions.
6. Quality Certifications & Compliance
Every coil tube product undergoes comprehensive quality assurance and carries the following certifications and compliance credentials:
| Certification / Standard | Description |
|---|---|
| GB/T 3639 | Chinese National Standard — Precision Seamless Steel Tubes (Dimensional & Mechanical Requirements) |
| GB 4806.9 | Chinese National Food Safety Standard — Food Contact Materials (Stainless Steel) |
| ISO 9001:2015 | Quality Management System Certification |
| ISO 14001:2015 | Environmental Management System Certification |
| ISO 22000 / HACCP | Food Safety Management System Certification |
| CE Marking | European Conformity for pressure equipment and food-contact applications |
| 3-A Sanitary Standard | Dairy, Food & Beverage Equipment (where applicable) |
| EN 10217 / ASTM A213 | International equivalent standards for seamless stainless steel tube |
7. Unique Selling Points
- Ultra-Precision Dimensions: Tolerances of ± 0.05 mm on outer diameter and ± 0.02 mm on wall thickness ensure perfect fit in automated hygienic fittings and sanitary connectors without the need for field adjustment.
- Hygienic Surface Excellence: Electropolished surfaces with Ra ≤ 0.4 μm eliminate micro-crevices and pitting, preventing biofilm formation and ensuring effective CIP/SIP decontamination cycles.
- Guaranteed Cleanliness: Full ultrasonic cleaning and nitrogen-drying protocol ensures zero residual contaminants, meeting the most stringent pharmaceutical and semiconductor purity requirements.
- Cost-Efficient Coil Configuration: Continuous coil format reduces material waste by up to 30% compared to cut-length pipe, lowers labor costs, and enables automated downstream processing.
- Full Traceability: Each coil is accompanied by a mill test certificate (MTC), chemical analysis report, and dimensional inspection data, enabling complete batch traceability throughout the supply chain.
- Multi-Grade Availability: Simultaneous offering of 304, 316, and 316L grades from a single supplier simplifies procurement and ensures consistent quality across diverse application requirements.
Wenzhou Jixing Metal Materials Co., Ltd — Committed to delivering hygienic-grade precision seamless stainless steel coil tube that meets the highest international standards for dimensional accuracy, surface integrity, and process cleanliness, enabling our customers to achieve uncompromised product quality in their most critical applications.