Stainless Steel Coil Tube (Coil Tube) — Wenzhou Jixing Metal Materials Co., Ltd.

1. Product Overview

The Stainless Steel Coil Tube (Product No. 1376) is a precision-engineered continuous coil form of stainless steel tubing manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is supplied in a coiled configuration, offering maximum material utilization, reduced cutting waste, and seamless integration into automated forming and fabrication lines. Coil tubes are widely recognized in industrial applications for their uniform dimensional accuracy, superior surface finish, and consistent metallurgical properties throughout the coil length.

Unlike straight-length tubing, coil tubes provide continuous material supply that minimizes butt-weld joints, thereby enhancing structural integrity and reducing potential leak points in pressure-containing systems. This makes them particularly suitable for hydraulic, pneumatic, heat exchanger, and fluid transport applications where reliability and corrosion resistance are paramount.

2. Material & Properties

2.1 Common Alloy Grades

2.2 Mechanical Properties (Typical — Annealed Condition, Grade 304L)

Property Value Standard Reference
Tensile Strength (Rm) ≥ 515 MPa (74,700 psi) ASTM A213 / A269
Yield Strength (Rp0.2) ≥ 205 MPa (29,700 psi) ASTM A213 / A269
Elongation (A50mm) ≥ 35% ASTM A213 / A269
Hardness (HBW) ≤ 200 ASTM E10
Specific Gravity 8.00 —
Thermal Conductivity (at 100°C) 16.3 W/(m·K) —
Linear Thermal Expansion (20–100°C) 17.3 × 10-6 /K —

2.3 Corrosion Resistance

Stainless steel coil tubes exhibit exceptional resistance to atmospheric corrosion, intergranular corrosion, and stress corrosion cracking (SCC), particularly in grades containing molybdenum (e.g., 316L). The low-carbon "L" designations (304L, 316L) provide enhanced resistance to sensitization during welding and high-temperature service.

3. Specifications

Parameter Specification Range Standard
Outer Diameter (OD) Φ 3.0 mm – Φ 219.1 mm (⅛" – 8") ASTM A269 / A213
Wall Thickness (WT) 0.3 mm – 12.7 mm (0.012" – 0.500") ASTM A269 / A213
OD Tolerance ± 0.05 mm – ± 0.50 mm (per diameter range) ASTM A213 Table 3
WT Tolerance ± 10% (min. ± 0.05 mm) ASTM A269 / A213
Coil Inner Diameter (ID) Φ 300 mm – Φ 1,500 mm Customer Specification
Coil Weight 500 kg – 3,000 kg per coil Customer Specification
Surface Finish No. 1 (Cold Rolled), 2B (Bright Annealed), BA (Bright Annealed), No. 4 (Brushed), HL (Hairline), Mirror (8K) ASTM A480 / ASME SA-480
Pickling & Passivation H2SO4/HNO3 pickling followed by nitric acid passivation ASTM A967
Heat Treatment Full Annealing (Solution Annealing) at 1050°C – 1150°C with water or air quench ASTM A213
End Condition Plain end, beveled end, threaded end, or capped end Customer Specification
Packaging Wooden crate, steel strapping, VCI (Vapor Corrosion Inhibitor) film, moisture-proof wrapping ISO 11607

4. Manufacturing Process

4.1 Process Flow Diagram

  1. Raw Material Receiving & Inspection: Ingot or billet material is received and subjected to spectrographic analysis for chemical composition verification (PMI — Positive Material Identification).
  2. Hot Rolling: Billet is reheated to 1,150°C – 1,250°C and hot-rolled into seamless tube blanks or ERW (Electric Resistance Welded) strip.
  3. Piercing & Enlarging: For seamless tubing, the hot billet is pierced through a mandrel and enlarged to the desired OD range.
  4. Cold Drawing / Cold Rolling: The hot-rolled tube is cold-drawn through precision dies or cold-rolled to achieve final OD, WT, and dimensional tolerances. This process enhances surface finish and mechanical properties.
  5. Solution Annealing: Tubes are annealed in a protective atmosphere (hydrogen or nitrogen) furnace at 1,050°C – 1,150°C to relieve cold-work stresses, restore ductility, and ensure uniform microstructure.
  6. Pickling & Passivation: Surface oxide scale is removed via acid pickling; a protective chromium oxide passive film is established through nitric acid passivation per ASTM A967.
  7. Hydrostatic Testing: Each tube is pressure-tested at 1.5× the maximum allowable working pressure (MAWP) to verify integrity and absence of porosity or defects.
  8. Coiling: Continuous tube is wound onto a coil former with controlled tension to prevent ovality, kinking, or springback. Coil geometry is verified for uniform pitch and ID.
  9. Final Inspection & Packaging: Dimensional verification, surface inspection, and mechanical testing are conducted before packaging for shipment.

4.2 Key Process Controls

5. Applications

5.1 Industrial Applications

5.2 Advantages of Coil Form

Continuous Supply: Eliminates butt-weld joints, reducing leak risk and improving system reliability.

Material Efficiency: Minimizes cutting losses — up to 15–20% material savings compared to straight lengths.

Automation Compatibility: Integrates seamlessly with automated tube-cutting, bending, and forming machinery.

Consistent Properties: Continuous production ensures uniform metallurgical properties along the entire coil length.

6. Quality Certifications

6.1 International Standards Compliance

Standard Scope
ASTM A213 Seamless and welded austenitic stainless steel tubing for high-temperature service
ASTM A269 Seamless, welded, and wrought austenitic stainless steel tubing for chemical and heat-exchange equipment
ASTM A480 / ASME SA-480 Sheet and plate for chemical and general applications (surface finish reference)
ASTM A967 Pickling and passivation of stainless steel parts
ASME BPVC Section VIII Pressure vessel and piping code compliance
EN 10216-5 European standard for seamless stainless steel tubes
GB/T 12771 Chinese national standard for austenitic stainless steel welded tubes
ISO 9001:2015 Quality Management System certification
ISO 14001:2015 Environmental Management System certification
ISO 45001:2018 Occupational Health and Safety Management System

6.2 Testing & Certification Services

7. Unique Selling Points