Stainless Steel Coil Tube (Coiltube) — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a continuous-length hollow cylindrical product manufactured in a coiled configuration, produced by Wenzhou Jixing Metal Materials Co., Ltd. (Product Code No. 1422). This product is designed for seamless, continuous processing in downstream fabrication operations including bending, forming, cutting, and welding. The coiled format eliminates the need for butt-welding multiple straight-length tubes, thereby reducing material waste, minimizing joint defects, and improving production efficiency in high-volume manufacturing environments.
Coiltubes are widely employed in heat exchanger manufacturing, chemical processing, pharmaceutical equipment, food-grade piping systems, automotive exhaust systems, and architectural applications where corrosion resistance, hygienic integrity, and mechanical reliability are paramount.
2. Material & Properties
2.1 Available Material Grades
- AISI 304 / ASTM A213 TP304 — General-purpose austenitic stainless steel with excellent corrosion resistance and formability.
- AISI 304L / ASTM A213 TP304L — Low-carbon variant (C ≤ 0.03%) suitable for welded applications and high-temperature service.
- AISI 316 / ASTM A213 TP316 — Molybdenum-bearing grade offering superior resistance to chlorides, pitting, and crevice corrosion.
- AISI 316L / ASTM A213 TP316L — Low-carbon molybdenum grade for enhanced weldability and cryogenic applications.
- AISI 321 / ASTM A213 TP321 — Titanium-stabilized grade resistant to intergranular corrosion at elevated temperatures (450–850 °C).
2.2 Mechanical Properties (Representative Values)
| Property | AISI 304 | AISI 316 | Test Standard |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 520 MPa | ≥ 515 MPa | ASTM A370 / EN 10002-1 |
| Yield Strength (Rp0.2) | ≥ 205 MPa | ≥ 205 MPa | ASTM A370 / EN 10002-1 |
| Elongation (A50) | ≥ 40% | ≥ 40% | ASTM A370 |
| Hardness (HV10) | ≤ 210 | ≤ 210 | ISO 6507 |
| Corrosion Resistance (ASTM A967) | Pass | Pass | ASTM A967 Passivation |
2.3 Chemical Composition (Typical, wt%)
| Element | C | Mn | P | S | Si | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|---|
| 304 | ≤ 0.08 | ≤ 2.00 | ≤ 0.045 | ≤ 0.030 | ≤ 1.00 | 18.00–20.00 | 8.00–10.50 | — | ≤ 0.10 |
| 316 | ≤ 0.08 | ≤ 2.00 | ≤ 0.045 | ≤ 0.030 | ≤ 1.00 | 16.00–18.00 | 10.00–14.00 | 2.00–3.00 | ≤ 0.10 |
3. Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | Φ 3.0 – Φ 168.3 mm (customizable) | ASTM A213 / EN 10216-5 |
| Wall Thickness (WT) | 0.25 – 8.00 mm | ASTM A213 |
| Coil Length | 100 – 1000 m per coil (standard); up to 2000 m on request | Internal specification |
| Coil Inner Diameter | Φ 200 / Φ 400 / Φ 600 mm | — |
| Surface Finish | 2B (No. 2 Bright Annealed), BA (Bright Annealed), No. 4 Brushed, No. 8 Mirror | ASTM A480M |
| Manufacturing Process | Seamless (Piercing + Pilger / Capillary) or Welded (ERW / Laser Welded + Internal Polishing) | ASTM A213 / EN 10216-5 |
| Heat Treatment | Solution Annealing (1050–1150 °C) followed by water quench; optional Pickling & Passivation | ASTM A967 |
| Dimensional Tolerance | OD: ±0.05 mm; WT: ±0.02 mm (precision grade); ±5% (standard grade) | ASTM A213 / EN 10216-5 |
| Packaging | Wooden pallet or steel frame; moisture-proof wrapping; seaworthy export packaging available | ISO 4180 |
4. Manufacturing Process
4.1 Seamless Coiltube Production
- Raw Material Receiving & Inspection — Hot-rolled coil (HRC) or cold-rolled coil (CRC) from certified mill sources undergoes incoming inspection for chemical composition (spectrometric analysis), mechanical properties, and surface quality.
- Blanking & Coil Forming — Flat strip is precision-cut to required width and fed into the forming station where progressive roller dies progressively shape the strip into a tubular profile.
- Welding (if applicable) — For welded coiltubes, high-frequency resistance welding (ERW) or laser welding joins the seam with sub-millimeter heat-affected zones. Internal weld bead removal is performed via mechanical grinding or electrochemical polishing for seamless internal surfaces.
- Continuous Annealing — The formed tube passes through a continuous annealing furnace (CAF) at 1050–1150 °C in a controlled reducing atmosphere (endothermic gas or vacuum) to achieve full solution treatment, grain refinement, and stress relief.
- Pickling & Passivation — The annealed tube is immersed in a mixed acid bath (HNO₃/HF or citric acid) to remove scale and form a protective chromium oxide passive film, enhancing corrosion resistance.
- Coiling & Pay-off — The finished tube is wound onto a mandrel with controlled tension to prevent deformation, kinking, or surface scratching.
- Final Inspection — 100% visual inspection, dimensional verification (OD, WT via ultrasonic measurement), hydrostatic pressure testing, and optional eddy-current or ultrasonic flaw detection.
4.2 Quality Control Milestones
| Inspection Stage | Method | Acceptance Criteria |
|---|---|---|
| Incoming Material | OES Spectroscopy + Mill Test Certificate (MTC) verification | ASTM A240 / EN 10088 compliance |
| In-Process (Weld Quality) | Ed current testing (ECT) | No cracks, incomplete fusion, or porosity |
| Post-Annealing | Hardness test (HV10) + Microstructure examination | Uniform austenitic structure; no martensite transformation |
| Final Product | Hydrostatic test + Dimensional measurement + Visual inspection | No leakage at 1.5× service pressure; dimensions within tolerance |
5. Applications
- Heat Exchangers & Boilers — Tubular bundles in shell-and-tube heat exchangers, condensers, evaporators, and boiler water tubes where thermal cycling and corrosive media exposure demand high durability.
- Chemical & Petrochemical Processing — Piping systems for transporting aggressive chemicals, acids, and hydrocarbons at elevated temperatures and pressures.
- Pharmaceutical & Bioprocessing — Clean-in-place (CIP) compatible piping for sterile fluid transfer; electropolished internal surfaces (Ra ≤ 0.4 μm) prevent bacterial adhesion.
- Food & Beverage Industry — Dairy processing, brewing, and beverage transfer lines requiring hygienic-grade surfaces and compliance with FDA/3-A standards.
- Automotive Industry — Exhaust system components, fuel lines, and sensor housings requiring corrosion resistance and high-temperature stability.
- Architectural & Decoration — Structural railings, handrails, and decorative elements with mirror or brushed finishes.
- Energy Sector — Solar thermal collectors, geothermal well casings, and nuclear-grade piping applications.
6. Quality Certifications & Standards Compliance
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| EN 10204 3.1 | Inspection Certificate — Material Test Certificate |
| ASTM A213 / A269 | Seamless and welded austenitic stainless steel tube specifications |
| EN 10216-5 | Non-alloy and stainless steel welded tubes — austenitic grades |
| ASME SA-213 / SA-269 | Pressure vessel and heat exchanger tube specifications |
| DIN EN 10088-2 | Technical delivery conditions for stainless steels |
| NSF / ANSI 61 | Drinking water system components (food-grade applications) |
| CE Marking | Compliance with European Pressure Equipment Directive (PED 2014/68/EU) |
| Mill Test Certificate (MTC) | Provided per EN 10204 3.1 with full chemical and mechanical data |
7. Unique Selling Points
Continuous Length Advantage: The coil format eliminates butt-weld joints, providing a seamless continuous tube that significantly reduces leak risk and material consumption in downstream fabrication. This results in cost savings of 5–12% compared to equivalent straight-length tube procurement.
- Multi-Grade Availability: A comprehensive range of austenitic grades (304, 304L, 316, 316L, 321) accommodates diverse service environments from atmospheric to highly aggressive corrosive media.
- Precision Dimensional Control: Advanced continuous annealing and precision forming technology ensures dimensional tolerances as tight as ±0.02 mm on wall thickness, critical for heat exchanger tube-sheet assembly.
- Surface Integrity: Optional electropolishing and passivation treatments deliver Ra ≤ 0.25 μm internal surface roughness, meeting pharmaceutical and food-grade hygienic requirements.
- Full Traceability: Every coil is accompanied by a complete Mill Test Certificate (EN 10204 3.1) with batch-specific chemical analysis, mechanical test data, and heat treatment records, enabling complete supply chain traceability.
- Customization Capability: Flexible production parameters allow customization of OD, wall thickness, surface finish, coil length, and packaging configuration to meet specific customer requirements.
- Environmental Compliance: Production processes adhere to ISO 14001 environmental management standards, with closed-loop acid recycling and zero liquid discharge (ZLD) treatment systems for pickling and passivation effluents.
8. Ordering Information
Customers are advised to specify the following parameters when placing orders:
- Material grade (e.g., AISI 316L)
- Outer diameter and wall thickness (mm)
- Required surface finish (2B, BA, No. 4, No. 8)
- Coil length requirement (m)
- Applicable standard (ASTM, EN, ASME, JIS)
- Special requirements (electropolishing, hydrostatic test pressure, packaging)
- Quantity and delivery schedule
For technical inquiries, sample requests, or custom specification development, contact the technical sales engineering team at Wenzhou Jixing Metal Materials Co., Ltd.