Stainless Steel Coil Tube — Whole-Coil Pricing Specification
1. Product Overview
The Stainless Steel Coil Tube (盘管 / Coil Tube) is a continuous-length tubular product formed by winding seamless or welded stainless steel tubes onto a steel spool or coil former. Unlike straight-length tube sections, coil tubes are supplied in bulk coil configurations, enabling efficient downstream processing through automated cutting, forming, and fabrication lines. This product is offered under a Whole-Coil Pricing Model (按卷定价), wherein the entire coil is sold at a single, unified price with no option for partial splitting or sub-division. This pricing structure is predominantly employed for stock clearance (现货清库) and tail-roll disposal (尾卷处理), ensuring inventory turnover efficiency and cost optimization for both manufacturer and purchaser.
2. Material & Properties
2.1 Base Material Grades
- AISI 304 / 304L (UNS S30400 / S30403) — General-purpose austenitic stainless steel with excellent corrosion resistance and formability
- AISI 316 / 316L (UNS S31600 / S31603) — Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion
- AISI 321 (UNS S32100) — Titanium-stabilized austenitic grade for high-temperature applications
- AISI 30432 (UNS S30432) — Dual-stabilized (Ti+ Nb) austenitic grade for elevated-temperature service
- AISI 310S (UNS S31008) — High-temperature austenitic grade with enhanced oxidation resistance
2.2 Mechanical Properties (Typical, Annealed Condition)
| Property | AISI 304 | AISI 316 | AISI 321 |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 515 | ≥ 515 |
| Yield Strength (MPa) | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 |
| Hardness (HB) | ≤ 217 | ≤ 217 | ≤ 217 |
| Maximum Service Temperature (°C) | 870 | 870 | 900 |
2.3 Chemical Composition (wt%, Maximum)
| Grade | C | Mn | P | S | Si | Cr | Ni | Mo | Other |
|---|---|---|---|---|---|---|---|---|---|
| 304 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–10.5 | — | N ≤ 0.10 |
| 316 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.00–3.00 | N ≤ 0.10 |
| 321 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 17.0–19.0 | 9.0–12.0 | — | 0.10–0.30 Ti (≥5×C) |
3. Specifications
| Parameter | Specification |
|---|---|
| Product Form | Coil Tube (盘管), wound onto steel spool |
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (1/4" – 2") |
| Wall Thickness | 0.5 mm – 3.0 mm |
| Coil Weight (Typical) | 500 kg – 3,000 kg per coil |
| Coil Length (Continuous) | 150 m – 1,200 m (dependent on OD and wall thickness) |
| Surface Finish | Pickled & Annealed (P&A), 2B, BA, or No.4 Brushed |
| Manufacturing Method | Seamless (Cold Drawn / Cold-Pilgered) or ERW Welded |
| Applicable Standards | ASTM A554, ASTM A213, EN 10216-5, GB/T 14976, JIS G3459 |
| Pricing Model | Whole-Coil Pricing (按卷定价) — Entire coil sold at one unified price; no splitting permitted |
| Minimum Order Quantity | 1 complete coil (no partial-coil transactions) |
| Coil Packaging | Steel band strapping + moisture-proof wrapping + export-grade pallet |
4. Manufacturing Process
The production of stainless steel coil tube follows a rigorous multi-stage manufacturing sequence:
- Raw Material Preparation: Cold-rolled stainless steel strip or seamless tube blanks are sourced from certified mills, with incoming material subjected to spectroscopic chemical analysis and ultrasonic flaw detection (UT).
- Forming: For welded coil tube, cold-rolled strip is fed through a roll-forming line where precision rollers progressively shape the strip into a tubular profile. For seamless coil tube, billets are hot-forged, pierced, and subsequently cold-drawn or cold-pilgered to achieve final dimensions.
- Welding (if applicable): ERW (Electric Resistance Welding) or TIG (Tungsten Inert Gas) welding is employed to close the tube seam, followed by internal grinding to smooth the weld zone.
- Heat Treatment: The formed tube undergoes solution annealing (固溶退火) at 1,010–1,150 °C in a protective atmosphere or vacuum, followed by controlled cooling. This process dissolves carbides, restores the austenitic microstructure, and eliminates residual stresses introduced during forming.
- Pickling & Passivation: The annealed tube is pickled in a mixed acid solution (HNO₃/HF or HNO₃/HCl) to remove oxide scale, followed by passivation to establish a stable chromium oxide (Cr₂O₃) protective film on the surface.
- Coiling: The continuous tube is wound onto a steel coil former (spool) using a computer-controlled coiling head that maintains uniform tension and consistent inter-pass spacing to prevent surface scratches and mechanical damage.
- Quality Inspection: Each coil undergoes 100% hydrostatic testing (per ASTM A530), dimensional verification (OD, wall thickness, roundness), surface inspection, and sampling for mechanical property and corrosion resistance testing.
- Packaging & Dispatch: Coils are wrapped, strapped, and palletized for storage or export shipment.
5. Applications
Stainless steel coil tubes are widely utilized across multiple industrial sectors, benefiting from the material's inherent corrosion resistance, mechanical strength, and hygienic surface properties:
- Automotive Industry: Exhaust system components, fuel lines, air intake ducts, and turbocharger piping
- Food & Beverage Processing: Sanitary piping, conveyor systems, and food-grade transport lines (AISI 304L / 316L)
- Pharmaceutical & Biotech: Clean-in-place (CIP) piping systems, bioreactor connections, and sterile fluid transfer lines
- Petroleum & Chemical: Heat exchanger tubes, reactor internals, and corrosion-resistant process piping
- Construction & Architecture: Structural handrails, decorative facades, and building infrastructure
- Medical Equipment: Endoscope channels, surgical instrument housings, and diagnostic device tubing
- Electronics & Aerospace: Precision tubing for sensor housings, heat sinks, and structural components
6. Quality Certifications & Compliance
Products manufactured by Wenzhou Jixing Metal Materials Co., Ltd. adhere to internationally recognized quality management and product standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- EN 10204 — Type 3.1 mill test certificates (MTC) provided with every shipment, including full chemical analysis, mechanical test results, and dimensional verification
- CE Marking — Conformity with European New Approach Directives for applicable products
- PED Compliance — Pressure Equipment Directive (2014/68/EU) for pressure-rated applications
- ASTM / ASME Compliance — Material and testing per ASTM A554, A213, A778, and ASME B36.19M
7. Unique Selling Points — Whole-Coil Pricing Model
Whole-Coil Pricing (按卷定价): The entire coil is offered at a single, unified price with no option for splitting or partial purchase. This model is particularly advantageous in the following scenarios:
- Cost Efficiency: By eliminating per-meter or per-length surcharges and splitting fees, buyers benefit from a lower unit cost (cost per meter), making this model ideal for high-volume fabrication operations.
- Inventory Optimization: This pricing structure is the preferred mechanism for stock clearance (现货清库) and tail-roll disposal (尾卷处理), enabling manufacturers to efficiently clear residual inventory and minimize warehousing costs.
- Supply Chain Simplification: A single transaction per coil reduces administrative complexity, accelerates order fulfillment, and minimizes logistical fragmentation.
- Predictable Procurement: Buyers receive a transparent, all-inclusive price per coil with no hidden charges for cutting, handling, or partial delivery — facilitating accurate budgeting and cost forecasting.
- Material Integrity: Selling the coil as a complete unit preserves the continuous integrity of the tube, avoiding end-seal damage, contamination, or dimensional irregularities that can occur during splitting operations.
Important Note: Purchasers under the Whole-Coil Pricing model must commit to acquiring the entire coil. Partial-coil transactions, split shipments, or post-purchase returns of residual material are not permitted under this pricing arrangement. Prospective buyers should verify that the coil length and weight align with their production requirements prior to order confirmation.
8. Conclusion
The Stainless Steel Coil Tube offered by Wenzhou Jixing Metal Materials Co., Ltd. represents a high-quality, standards-compliant tubular product designed for demanding industrial applications. The Whole-Coil Pricing model provides a transparent, cost-effective procurement pathway optimized for bulk consumption, inventory clearance, and supply chain efficiency. With comprehensive quality assurance, international certifications, and a broad range of available grades and dimensions, this product line serves as a reliable solution for OEM manufacturers, fabrication shops, and industrial distributors worldwide.