Stainless Steel Coil Tube (Coiltube) — Technical Product Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered continuous-length tubing product, manufactured in a coiled configuration for efficient storage, transportation, and downstream processing. Produced by Wenzhou Jixing Metal Materials Co., Ltd, this product is designed to meet the demanding requirements of industrial heat exchange systems, HVAC (Heating, Ventilation, and Air Conditioning) applications, chemical processing, food-grade equipment, and fluid conveyance systems.
The coil tube is supplied in a continuous helical form, eliminating the need for field welding at supply length, thereby reducing installation labor, minimizing leak points, and ensuring structural integrity throughout the service life of the system. The product is particularly suited for applications requiring high corrosion resistance, thermal stability, and hygienic standards.
2. Material and Properties
2.1 Base Material Grades
- ASTM A213 / ASME SA-213 — Standard specification for austenitic stainless steel tubing
- ASTM A269 — Specification for welded austenitic stainless steel tubing
- EN 10216-5 — European standard for seamless stainless steel tubes
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
2.2 Commonly Available Grades
- 304 (UNS S30400) — General-purpose austenitic grade with excellent corrosion resistance
- 304L (UNS S30403) — Low-carbon variant for improved weldability and reduced sensitization risk
- 316 (UNS S31600) — Molybdenum-bearing grade with superior resistance to pitting and crevice corrosion
- 316L (UNS S31603) — Low-carbon 316 for demanding chloride environments
- 321 (UNS S32100) — Titanium-stabilized grade for high-temperature service
- 310S (UNS S31008) — High-temperature oxidation-resistant grade
2.3 Mechanical Properties (Typical — Grade 304)
- Tensile Strength: ≥ 515 MPa (75 ksi)
- Yield Strength (0.2% offset): ≥ 205 MPa (30 ksi)
- Elongation: ≥ 40% (in 50 mm / 2 in)
- Hardness: ≤ 217 HB (Brinell)
- Density: 8.0 g/cm³
- Thermal Conductivity: 16.3 W/(m·K) at 100°C
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /°C (20–100°C)
2.4 Chemical Composition (Typical — Grade 304)
| Element | C (Carbon) | Mn (Manganese) | P (Phosphorus) | S (Sulfur) | Si (Silicon) | Cr (Chromium) | Ni (Nickel) | N (Nitrogen) | Fe (Iron) |
|---|---|---|---|---|---|---|---|---|---|
| Max / Min (%) | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–10.5 | — | Balance |
3. Specifications
| Parameter | Specification / Range |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 159.0 mm (1/4" – 6") |
| Wall Thickness | 0.5 mm – 8.0 mm (0.020" – 0.315") |
| Coil Length (Continuous) | Up to 500 m (1,640 ft) per coil, custom lengths available |
| Coil Inner Diameter | 450 mm – 1,200 mm (adjustable per order) |
| Surface Finish | Machined, Polished (2B), Electropolished (Ra ≤ 0.5 μm), Pickled & Passivated |
| Tolerance (OD) | ±0.10 mm (standard), ±0.05 mm (precision grade) |
| Tolerance (Wall) | ±10% of nominal wall thickness |
| Manufacturing Method | Seamless (Cold Drawn / Hot Rolled) or Welded (ERW / TIG) |
| Temperature Range | −196°C to +870°C (Grade 304); up to +1,150°C (Grade 310S) |
| Maximum Working Pressure | Determined by OD, wall thickness, and grade per ASME B31.3 |
| End Treatment | Plain cut, beveled, threaded, or with pre-formed fittings |
| Coating / Passivation | Passivated (nitric acid or citric acid), optional PTFE inner coating |
4. Manufacturing Process
4.1 Seamless Coil Tube Production
- Raw Material Selection — Ingot or billet procurement from certified stainless steel mills; 100% chemical composition verification via spectroscopic analysis.
- Hot Rolling / Forging — Billet heated to 1,150–1,200°C and hot-rolled or forged into a hollow billet (pierce).
- Hot Extrusion — Hollow billet extruded through a die to achieve preliminary tube dimensions.
- Cold Drawing — Tube drawn through precision dies to achieve final OD and wall thickness within tight tolerances; multiple passes for high-precision grades.
- Intermediate Annealing — Solution annealing at 1,050–1,100°C followed by water quench to restore ductility between cold-drawing passes.
- Coiling — Continuous tube wound onto a coil mandrel using a CNC-controlled coiling head to maintain uniform curvature and avoid deformation.
- Pickling & Passivation — Acid cleaning (HNO₃/HF blend) to remove scale, followed by passivation treatment to form a stable chromium oxide layer.
- Non-Destructive Testing (NDT) — 100% eddy current testing and hydrostatic pressure testing per ASTM A315.
- Final Inspection & Packaging — Dimensional verification, surface inspection, coil wrapping with protective film, and wooden crate or steel drum packaging.
4.2 Welded Coil Tube Production
- Strip Slitting — Cold-rolled stainless steel strip slit to precise width and thickness.
- Forming & Welding — Strip formed into a tube shape and continuously welded (TIG/ERW) at high speed.
- Weld Annealing — Solution heat treatment to relieve residual stresses in the weld zone.
- Precision Sizing — Final cold sizing to achieve dimensional tolerances.
- Coiling, Cleaning, and Inspection — As per seamless process above.
5. Applications
- HVAC & Heat Exchange Systems — Chilled water coils, condenser tubes, evaporator coils, and fan coil unit (FCU) internal tubing where continuous coil form reduces installation joints.
- Chemical Processing — Reactor internals, heat exchanger bundles, and process piping in corrosive environments (acids, chlorides).
- Food & Beverage Industry — CIP (Clean-in-Place) compatible tubing for dairy, brewery, and pharmaceutical processing lines.
- Power Generation — Boiler tubes, superheater elements, and condensate return lines in thermal and nuclear power plants.
- Oil & Gas — Subsea umbilicals, wellhead tubing, and offshore heat exchanger coils.
- Automotive — Turbocharger manifolds, fuel system lines, and exhaust components.
- Medical Devices — Endoscopy tubing, infusion lines, and surgical instrument shafts requiring electropolished surfaces.
6. Quality Certifications and Standards Compliance
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System
- ASME "S" Stamp — Authorized for pressure-containing applications
- EN 10204 3.1 — Material test certificates per European standard
- NACE MR0175 / ISO 15156 — Compliance for sour service environments (Grade 316L)
- 3-A Sanitary Standards — For food and pharmaceutical grade applications
- PED (Pressure Equipment Directive 2014/68/EU) — CE marking for European market
- SGS / Bureau Veritas Third-Party Inspection — Available upon request
7. Unique Selling Points
Continuous Coil Configuration: Eliminates field-weld joints, reducing leak risk and installation cost by up to 30% compared to straight-length tubing.
Full Traceability: Every coil is batch-traceable from raw material heat number through final NDT records, providing complete supply chain documentation.
Customization Capability: Tailored OD, wall thickness, coil length, surface finish, and end treatment to meet project-specific engineering requirements.
Advanced NDT: 100% inline eddy current and hydrostatic testing ensures zero-defect delivery.
Multi-Grade Availability: Inventory of 304, 316L, 321, and 310S grades enables rapid response to diverse corrosion and temperature demands.
8. Ordering Information
| Order Parameter | Required Information |
|---|---|
| Material Grade | Specify UNS designation (e.g., S30400, S31603) |
| Dimensions | OD × Wall Thickness (mm or inches) |
| Coil Length | Total meterage or weight per coil |
| Surface Finish | 2B / Electropolished / Passivated / Custom Ra value |
| End Treatment | Plain / Beveled / Threaded / Pre-fitted |
| Applicable Standard | ASTM / EN / GB / ASME / Custom |
| Certification Requirement | EN 10204 3.1 / 3.2 / MTC / Third-party inspection |
For detailed quotations, technical drawings, and sample evaluation, please contact Wenzhou Jixing Metal Materials Co., Ltd directly with your project specifications.