Stainless Steel Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (also referred to as Coiltube or Coiled Tubing) is a continuously wound, seamless or welded stainless steel tube product supplied in coil form for downstream forming, bending, and fabrication applications. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product is engineered for superior formability, corrosion resistance, and dimensional consistency. The coil tube is produced using a follow-up type pressure roller system (跟进式压轮) integrated into the coiling machinery, which ensures uniform wall thickness, minimizes ovality, and maintains precise geometric tolerances throughout the coiling process.
Coil tubes are distinct from straight-length tubes in that they are wound into large-diameter coils, enabling efficient handling, transportation, and continuous feed into fabrication lines. This format is particularly advantageous for applications requiring extensive bending, shaping, or cutting operations where material waste is a critical concern.
2. Material & Properties
2.1 Base Alloy Grades
Stainless steel coil tubes are available in a range of austenitic, ferritic, and duplex stainless steel grades, selected based on application requirements for corrosion resistance, mechanical strength, and temperature performance.
- Austenitic Grades: AISI 304, AISI 304L, AISI 316, AISI 316L, AISI 321, AISI 310S — offering excellent corrosion resistance, non-magnetic properties, and high ductility suitable for forming operations.
- Ferritic Grades: AISI 430, AISI 439 — providing cost-effective solutions with good atmospheric corrosion resistance and moderate formability.
- Duplex Grades: AISI 2205, AISI 2507 — delivering a balanced combination of high yield strength and superior chloride pitting resistance.
2.2 Mechanical Properties (Typical — Annealed Condition)
| Property | AISI 304 | AISI 316 | AISI 2205 |
|---|---|---|---|
| Tensile Strength (MPa) | 515 – 715 | 515 – 715 | ≥ 550 |
| Yield Strength (MPa) | ≥ 205 | ≥ 205 | ≥ 450 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 25 |
| Hardness (HB) | ≤ 217 | ≤ 217 | ≤ 320 |
| Corrosion Resistance (ASTM G48) | Good (moderate Cl⁻) | Excellent (high Cl⁻) | Superior (high Cl⁻) |
| Maximum Service Temperature (°C) | 870 | 870 | 300 (duplex limit) |
2.3 Surface Condition
Available in multiple surface finishes to suit downstream processing and end-use requirements:
- No. 1 Finish (Heat-Treated): Unpolished, matte surface; suitable for further mechanical processing.
- 2B Finish (Cold-Rolled & Annealed): Smooth, dull grey surface; standard for general fabrication.
- BA Finish (Bright Annealed): Mirror-like surface achieved in a controlled atmosphere furnace; ideal for decorative and hygienic applications.
- Polished Finishes: 240#, 320#, 400# grit polishing for cosmetic applications.
3. Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 168.3 mm (1/4" – 6") | ASTM A554 / EN 10217 |
| Wall Thickness | 0.5 mm – 8.0 mm (0.020" – 0.315") | ASTM A554 |
| OD Tolerance | ±0.10 mm (±0.004") | — |
| Wall Thickness Tolerance | ±10% of nominal | ASTM A554 |
| Coil Inner Diameter | 500 mm / 600 mm (standard); custom available | — |
| Coil Outer Diameter | 1,200 mm – 2,000 mm (max.) | — |
| Coil Weight | 500 kg – 3,000 kg (per coil) | — |
| Ovality | ≤ 1.0% of nominal OD | EN 10217 |
| Length per Coil | Continuous (typically 200 m – 1,500 m) | — |
| Heat Treatment | Solution Annealed (1050 – 1150 °C) + Water Quenched | ASTM A554 |
| End Condition | Open end, capped, or welded per customer specification | — |
| Packaging | Wooden pallet with steel strapping, VCI paper wrapping, seaworthy export packaging | — |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Selection: High-purity stainless steel slabs or billets conforming to ASTM/EN/GB standards are procured from certified mills. Incoming material undergoes spectroscopic analysis (OES) to verify chemical composition.
- Hot Rolling & Hot Finishing: Slabs are reheated to 1,100 – 1,250 °C and hot-rolled into seamless pipe blanks or hot-rolled coil stock, depending on the tube construction method (seamless vs. ERW/DW).
- Cold Drawing / Cold Rolling: The hot-rolled stock is cold-worked to achieve precise dimensional tolerances and enhanced mechanical properties. Cold drawing is performed in a multi-stage process to control the degree of work hardening.
- Solution Annealing: Tubes are heat-treated at 1,050 – 1,150 °C followed by rapid quenching (water or air) to dissolve carbides, restore ductility, and achieve a fully austenitic microstructure free of sensitization.
- Coiling with Follow-Up Pressure Roller System: The annealed tubes are wound into coils using a follow-up type pressure roller (跟进式压轮) mechanism. This system applies synchronized, adjustable radial pressure to the tube during the coiling operation, preventing tube deformation, maintaining roundness, and ensuring uniform coil layering. The pressure roller follows the tube path in real time, compensating for dynamic forces and maintaining consistent contact pressure throughout the winding cycle.
- Quality Inspection: Each coil undergoes dimensional inspection (OD, wall thickness, ovality), visual surface examination, hydrostatic testing (where applicable), and chemical/microstructural verification.
- Packaging & Dispatch: Coils are secured on export-grade wooden pallets with steel strapping, wrapped in VCI (Volatile Corrosion Inhibitor) paper, and labeled with full traceability documentation.
4.2 Follow-Up Pressure Roller Technology
The follow-up pressure roller is a critical component in the coiling process for stainless steel coil tubes. Unlike conventional fixed-pressure coiling systems, the follow-up roller dynamically adjusts its position and pressure in response to the tube's movement, ensuring:
- Minimized ovality and cross-sectional distortion during winding.
- Reduced inter-coil surface marking and cosmetic defects.
- Consistent layer-to-layer contact pressure, preventing coil looseness or excessive compaction.
- Improved downstream uncoiling performance, reducing springback and tube buckling during fabrication.
5. Applications
Stainless steel coil tubes are utilized across a broad spectrum of industrial applications due to their combination of corrosion resistance, formability, and dimensional precision:
- Automotive Industry: Exhaust system components, fuel lines, air intake ducts, and structural brackets — where the coil format enables continuous tube-rolling and bending operations.
- Oil & Gas / Petrochemical: Downhole tubing, wellhead components, and process piping — particularly in 316L and duplex grades for sour service environments.
- Food & Pharmaceutical Processing: Hygienic piping, heat exchanger tubes, and process vessels requiring BA or polished finishes and compliance with FDA/3-A standards.
- Architecture & Decoration: Handrails, elevator cladding, structural framing, and decorative trim — leveraging the aesthetic quality of BA and polished finishes.
- Medical Devices: Surgical instrument tubing, implant components, and diagnostic equipment housings requiring high-purity, biocompatible materials.
- Electronics & Semiconductors: Vacuum chamber components, gas delivery lines, and cleanroom-compatible tubing.
- General Fabrication: Coil tubes serve as feedstock for tube-rolling, bending, cutting, and welding operations in custom fabrication shops.
6. Quality Certifications & Standards Compliance
| Standard / Certification | Scope |
|---|---|
| ASTM A554 / A554M | Standard Specification for Stainless Steel Tubes (Cold-Drawn, Welded, and Seamless) — primary product standard |
| ASTM A269 | Welded Austenitic Stainless Steel Tubing for Chemical and Similar Severe Service |
| EN 10217-7 | Technical Delivery Conditions for Stainless Steel Tubes — Pressure Tubing |
| ISO 9001:2015 | Quality Management System certification for manufacturing processes |
| ISO 3834 | Quality requirements for welding of metallic materials (welded tube applications) |
| PED 2014/68/EU | Pressure Equipment Directive compliance (for pressure-rated applications) |
| Mill Test Certificates (MTC) | EN 10204 Type 3.1 certificates provided with every shipment |
| Material Traceability | Full heat-number traceability from raw material mill through to finished coil |
7. Unique Selling Points
- Follow-Up Pressure Roller Coiling: Proprietary coiling technology ensures superior dimensional accuracy, minimal ovality, and reduced surface defects — critical for downstream forming applications.
- Wide Grade & Size Range: Single-source supply across austenitic, ferritic, and duplex grades in a broad range of OD and wall thickness dimensions.
- Custom Coiling Configuration: Tailored coil ID, OD, and weight specifications to match customer uncoiling equipment and production line requirements.
- Full Traceability & Documentation: Every coil is accompanied by EN 10204 3.1 MTC with complete chemical composition, mechanical test results, and heat treatment records.
- Export-Grade Packaging: Seaworthy, moisture-protected packaging suitable for international logistics and long-term storage.
Supplier: Wenzhou Jixing Metal Materials Co., Ltd. — Specialized in stainless steel coil tube manufacturing with expertise in advanced coiling technologies and comprehensive material certification.