Thick-Wall Stainless Steel Coil Tube (1.5 mm – 3.0 mm+)
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
Product Category: Product Specifications → Geometric Parameters → Wall Thickness Series
Designation: Thick-Wall Coil Tube (Coiltube)
1. Product Overview
The Thick-Wall Stainless Steel Coil Tube represents a premium-grade coiled pipe product engineered for demanding industrial applications where structural integrity, high-pressure resistance, and exceptional wear durability are paramount. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product line delivers wall thicknesses ranging from 1.5 mm to 3.0 mm and beyond, distinguishing it from standard thin-wall coil tubes and positioning it as a specialized solution for critical infrastructure and heavy-duty engineering projects.
Unlike conventional coil tubes designed primarily for fluid conveyance or general-purpose tubing, the thick-wall variant is specifically optimized to withstand elevated internal pressures, resist mechanical abrasion, and provide robust structural support in applications where failure tolerance is minimal. The coil (spool) configuration offers logistical advantages including reduced handling costs, efficient storage, and on-site forming flexibility without the need for additional welding or joining.
2. Material & Properties
2.1 Base Material Composition
The thick-wall coil tube is typically fabricated from austenitic stainless steel grades, most commonly:
- AISI 304 (UNS S30408): Chromium-Nickel austenitic stainless steel offering excellent corrosion resistance, formability, and weldability.
- AISI 316 (UNS S31603): Molybdenum-enhanced austenitic stainless steel providing superior resistance to pitting and crevice corrosion, particularly in chloride-rich environments.
- AISI 321 (UNS S32100): Titanium-stabilized grade suitable for elevated-temperature service and environments requiring resistance to intergranular corrosion.
2.2 Key Mechanical Properties
- Tensile Strength: ≥ 515 MPa (AISI 304, annealed condition)
- Yield Strength: ≥ 205 MPa (0.2% offset)
- Elongation: ≥ 40% (minimum, at break)
- Hardness: ≤ 217 HB (annealed condition)
- Operating Temperature Range: −196°C to +870°C (depending on grade)
2.3 Corrosion Resistance
- Excellent resistance to atmospheric, chemical, and aqueous environments
- Outstanding performance in acidic and alkaline solutions
- Non-magnetic in the annealed condition (austenitic grades)
- Conforms to ASTM A270, ASTM A312, EN 10216-5, and GB/T 12771 standards for corrosion performance
3. Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Wall Thickness | 1.5 mm – 3.0 mm (extendable to 3.0 mm+ upon request) | GB/T 12771, ASTM A312 |
| Outer Diameter (OD) | 6.0 mm – 219.0 mm (typical range for coil tube) | ASTM A270, EN 10217-7 |
| Inner Diameter (ID) | Calculated per OD and wall thickness tolerance | ±10% of specified wall thickness |
| Coil Length | 5 m – 200 m (customizable per order) | Manufacturer specification |
| Coil Inner Diameter | 300 mm – 600 mm (standard) | ISO 4035 |
| Surface Finish | Pickled & Annealed (PA), 2B, No. 1, or custom (No. 4, Mirror) | ASTM A270 Table 5 |
| Heat Treatment | Annealed at 1050–1150°C followed by controlled cooling | ASTM A312, Section 8 |
| Pressure Rating | Up to 30 MPa (PN300) at room temperature (grade-dependent) | EN 10204, ASME B31.3 |
| Wall Thickness Tolerance | ±10% (standard) or ±5% (close tolerance) | GB/T 12771, ASTM A312 |
| Maximum Working Pressure (MWOP) | Calculated per Barlow formula: P = 2St/D | ASME B31.3, EN 13480 |
| Material Grades | AISI 304, 304L, 316, 316L, 321, 310S, 904L, Duplex 2205 | ASTM A213, A269, A270 |
4. Manufacturing Process
The production of thick-wall stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous, multi-stage manufacturing process ensuring dimensional accuracy, metallurgical quality, and mechanical performance:
- Raw Material Selection: Hot-rolled stainless steel strip (coil) is sourced from certified mills, with full chemical composition analysis (spectrometry) and mechanical property verification prior to acceptance.
- Edge Milling & Cleaning: The strip edges are milled to remove scale, oxidation, and imperfections. The surface is then cleaned to ensure uniform forming characteristics.
- Forming (Coiling): The prepared strip is fed through a series of progressive forming rolls that gradually bend and shape the flat strip into a tubular configuration. For thick-wall applications, the forming sequence is carefully calibrated to prevent wrinkling, cracking, or excessive work hardening at the longitudinal seam.
-
Seam Welding: A longitudinal seam weld is applied using either:
- High-Frequency Induction Welding (HF): Preferred for production efficiency and consistent weld quality.
- Pulsed TIG Welding: Used for applications requiring superior weld integrity and minimal heat-affected zone.
- Post-Weld Annealing: The formed and welded tube is annealed at temperatures between 1050–1150°C in a protective atmosphere (nitrogen or vacuum) to restore full austenitic microstructure, relieve residual stresses, and achieve specified mechanical properties.
- Pickling & Descaling: Surface oxide scale formed during annealing is removed through acid pickling (typically using a citric acid or nitric-hydrofluoric acid blend), yielding a clean, corrosion-resistant surface.
- Dimensional Calibration: The tube passes through a calibration (reduction) stand to achieve precise outer diameter and wall thickness tolerances. For thick-wall tubes, this step is critical to ensure uniformity around the circumference.
- Coiling & Packaging: The finished tube is coiled onto a mandrel of the specified inner diameter, securely strapped, and packaged with moisture-proof wrapping and protective end caps to prevent damage during transit.
5. Applications
The thick-wall stainless steel coil tube (1.5 mm – 3.0 mm+) is specifically engineered for high-performance applications where conventional thin-wall tubing would be insufficient. Key application domains include:
5.1 High-Pressure Systems
- High-pressure hydraulic and pneumatic line tubing
- Compressed gas transfer systems (oil & gas industry)
- Chemical process piping operating above 10 MPa
- Hydrogenation and ammonia synthesis plant tubing
- Power generation boiler feedwater and superheated steam lines
5.2 Wear-Resistant Service
- Slurry transport and pneumatic conveying systems
- Mineral processing and ore handling pipelines
- Wastewater treatment plant internals and effluent lines
- Food processing equipment requiring high mechanical durability
- Abrasive media blasting and shot peening equipment
5.3 Structural Support
- Architectural and structural framing (staircases, railings, handrails)
- Heavy-duty furniture and equipment frames
- Automotive and aerospace structural brackets and mounts
- Industrial machinery support structures and guardrails
- Marine and offshore structural components
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and holds the following certifications and complies with international standards:
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System — Design, manufacturing, and supply of stainless steel products |
| ISO 14001:2015 | Environmental Management System |
| EN 10204 3.1 | Material Inspection Certificate — Test reports with detailed results |
| EN 10204 3.2 | Material Test Report (Mill Certificate) — Available upon request |
| CE Marking | Compliance with European CE directives for pressure equipment |
| PED 2014/68/EU | Pressure Equipment Directive compliance (for pressure-rated applications) |
| ASME / NB | National Board registration for pressure vessel and piping components |
| ASTM A270 / A312 | Material and dimensional compliance for welded austenitic stainless steel tube |
| GB/T 12771 | Chinese national standard for welded austenitic stainless steel tubes |
| EN 10217-7 / EN 10216-5 | European standards for cold-drawn and hot-finished stainless steel tubes |
6.1 Quality Assurance Protocol
Every production batch undergoes the following quality control procedures:
- Chemical Analysis: Full spectrographic analysis of carbon, chromium, nickel, molybdenum, manganese, silicon, sulfur, and phosphorus content verified against grade specifications.
- Mechanical Testing: Tensile testing, hardness testing (Rockwell/Brinell), and bend testing performed per ASTM E8 and ASTM E10.
- Dimensional Inspection: Laser-based OD measurement, ultrasonic wall thickness gauging, and roundness verification at multiple intervals along the coil length.
- Non-Destructive Testing (NDT): 100% eddy current testing (ECT) or magnetic particle inspection (MPI) of the longitudinal seam weld to detect discontinuities, porosity, or incomplete fusion.
- Hydrostatic Pressure Testing: Applied pressure of 1.5× the design working pressure, held for minimum 5 seconds with zero leakage tolerance.
- Surface Quality Inspection: Visual and magnification inspection for surface defects, scratches, inclusions, or decarburization.
7. Unique Selling Points
"Engineered for Pressure. Built for Longevity. Coiled for Convenience."
- Extended Wall Thickness Capability: The 1.5 mm to 3.0 mm+ wall thickness range provides a significant margin of safety for high-pressure and high-stress applications, exceeding the capabilities of standard coil tube manufacturers.
- Pressure Performance: Thick-wall geometry delivers pressure ratings up to PN300 (30 MPa), enabling use in critical process industries without the need for additional reinforcement or thicker-walled seamless alternatives at higher cost.
- Wear Resistance: The combination of austenitic stainless steel metallurgy and substantial wall thickness provides outstanding resistance to erosive wear, extending service life in abrasive environments.
- Structural Versatility: The thick-wall profile offers high bending moment resistance and load-bearing capacity, making it suitable for structural applications that demand both corrosion resistance and mechanical strength.
- Coil Form Advantages: Delivered in coil configuration for superior logistics efficiency — reduced packaging volume, easier handling, and the ability to draw and form the tube on-site into complex geometries without butt welds.
- Full Traceability: Complete batch traceability from raw material mill certificate through final inspection, ensuring compliance with international regulatory and quality standards.