Seamless Stainless Steel Coil Tube — Hot Pierced & Cold Rolled
Product Overview
The Seamless Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a premium-grade tubing solution produced through a traditional hot piercing and cold rolling seamless manufacturing process. Unlike welded coil tubes, this product delivers a continuous, weld-free tube wall that ensures superior mechanical integrity, exceptional corrosion resistance, and uniform material properties throughout the entire cross-section.
This coil tube is specifically engineered for applications demanding high-pressure resistance, thermal stability, and long-term reliability in demanding industrial environments. The seamless construction eliminates the inherent weak points associated with welded joints, making it an ideal choice for critical service applications where structural integrity and material homogeneity are paramount.
Material & Properties
The seamless coil tube is available in a range of austenitic and duplex stainless steel grades, including but not limited to:
- 304 / 304L — Excellent general corrosion resistance, widely used in food processing and chemical industries
- 316 / 316L — Superior resistance to chlorides and pitting corrosion, ideal for marine and chemical environments
- 321 / 347 — Stabilized grades with enhanced resistance to intergranular corrosion at elevated temperatures
- 310S — High-temperature oxidation resistance, suitable for furnace components and heat treatment equipment
- 904L / 2205 Duplex — Ultra-low carbon and high-alloy grades for aggressive chemical and offshore applications
Key material properties include:
- Non-magnetic (austenitic grades) or low magnetic permeability
- High tensile strength with excellent ductility
- Outstanding resistance to oxidation at temperatures up to 870°C (grade-dependent)
- Low carbon variants (L grades) available for enhanced weldability and reduced sensitization risk
Specifications
| Parameter | Specification |
|---|---|
| Manufacturing Method | Hot Piercing + Cold Rolling (Seamless) |
| Outer Diameter Range | 6 mm – 219 mm (custom sizes available upon request) |
| Wall Thickness Range | 0.5 mm – 12 mm (wide range — key advantage of seamless process) |
| Single Tube Length | Up to 30 m per piece (straight length) |
| Coil Formation | Achieved via precision butt welding and splicing of individual straight tubes |
| Surface Finish | Mill finish, polished (2B), pickled & passivated, or custom finishes |
| Available Grades | 304, 304L, 316, 316L, 321, 347, 310S, 904L, 2205 Duplex, and others |
| Standards Compliance | ASTM A213 / A269, ASME SA-213 / SA-269, EN 10216-5, GB/T 12771 |
| Delivery Condition | Annealed, Solution Heat Treated, or Cold Worked as specified |
| Order Quantity | Flexible — supports both standard and custom-length orders |
Manufacturing Process
Hot Piercing
The manufacturing process begins with high-quality stainless steel billets, which are heated to forging temperature and pierced using a mandrel-driven hot piercing mill. This step creates a hollow round bar (Hollow Bar or Hob) with the desired inner diameter and outer diameter proportions. The hot piercing stage establishes the initial tube geometry and ensures sound, defect-free material flow.
Cold Rolling
The hollow bar is then subjected to a series of cold rolling passes through progressively reducing roll sets. This cold working stage achieves the final dimensions with high dimensional accuracy (typically ±0.1 mm on diameter and ±0.05 mm on wall thickness), imparts beneficial work-hardening, and produces a smooth, uniform surface finish. Cold rolling also enhances mechanical properties through controlled grain refinement.
Post-Processing & Coil Formation
Following cold rolling, the tubes undergo stress-relief annealing or solution heat treatment to restore full ductility and achieve the desired metallurgical structure. The tubes are then straightened, cut to the specified length (up to 30 m per piece), and inspected for dimensional accuracy and surface quality.
To form the coil configuration, individual straight tubes are joined using high-precision orbital butt welding or flash butt welding, followed by internal and external weld inspection (including eddy current testing and visual examination) to ensure full penetration and defect-free joints. The welded assemblies are then coiled into the required coil diameter for convenient handling, storage, and downstream processing.
Key Selling Points
- Wide Wall Thickness Range: The seamless hot piercing + cold rolling process enables production of tubes across an exceptionally broad wall thickness spectrum (0.5 mm to 12 mm), offering unmatched flexibility for diverse application requirements that single-process methods cannot accommodate.
- True Seamless Integrity: Unlike welded coil tubes, this product features a continuous, weld-free tube wall, providing superior resistance to pressure, fatigue, and corrosion attack at the wall surface.
- High Dimensional Precision: Cold rolling delivers tight tolerances on both outer diameter and wall thickness, reducing downstream machining costs and improving fit-up accuracy.
- Multi-Grade Availability: A comprehensive selection of stainless steel grades ensures the right material solution for every application, from general industrial use to highly corrosive or high-temperature environments.
- Reliable Coil Configuration: The coil format facilitates efficient uncoiling, straightening, and automated processing, significantly improving production line throughput and reducing material waste.
- Full Traceability: Each batch is accompanied by mill test certificates (MTC) with full chemical and mechanical property documentation, ensuring complete material traceability.
Applications
The Seamless Stainless Steel Coil Tube is widely utilized across multiple industries where material integrity, corrosion resistance, and dimensional precision are critical:
- Chemical & Petrochemical Processing: Reactor piping, heat exchanger tubes, distillation columns, and process piping systems handling aggressive chemicals
- Food & Beverage Industry: Hygienic process piping, brewing equipment, dairy processing lines, and pharmaceutical-grade fluid transfer systems (FDA-compliant surface finishes available)
- Oil & Gas: Downhole tubing, wellhead components, and offshore platform piping systems
- Power Generation: Boiler tubes, superheater elements, condenser tubes, and nuclear-grade applications
- Automotive & Aerospace: Exhaust system components, fuel lines, hydraulic tubing, and structural elements
- Medical Devices: Surgical instrument tubing, endoscope shafts, and implant-grade applications
- Marine & Offshore: Seawater cooling systems, ballast water piping, and marine structural components
Quality Certifications & Testing
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality control throughout the entire manufacturing process. All products are manufactured in accordance with international standards and undergo comprehensive testing:
- Material Certification: EN 10204 Type 3.1 mill test certificates with full chemical composition and mechanical property data
- Dimensional Inspection: 100% dimensional verification using calibrated gauges and automated measurement systems
- Non-Destructive Testing (NDT): Eddy current testing, ultrasonic testing (UT), and visual inspection for surface and internal defects
- Hydrostatic Testing: Pressure testing to verify structural integrity and weld quality at coil splice joints
- Surface Quality: Visual and profilometric inspection to confirm surface finish grade
- Corrosion Testing: Salt spray testing and intergranular corrosion testing (ASTM A923) for relevant grades
Standards Compliance: ASTM A213 / A269 | ASME SA-213 / SA-269 | EN 10216-5 | GB/T 12771 | ISO 9001:2015 Quality Management System
With decades of expertise in seamless stainless steel tube manufacturing, Wenzhou Jixing Metal Materials Co., Ltd. is committed to delivering products that meet the most demanding specifications. For custom requirements, special grades, or large-volume orders, our technical team provides dedicated support from design consultation through delivery.