Stainless Steel Coil Tube — Actual Weighing Settlement Specification
Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) offered by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular product supplied in continuous coil form. This product is primarily categorized under commercial procurement and is distinguished by its Actual Weighing Settlement pricing methodology — a transparent, industry-leading approach that ensures buyers are charged based on the true net weight of the material received, as measured by calibrated floor scales (地磅) and hoist scales (吊秤).
Unlike theoretical weight calculations derived from nominal dimensions and density, the Actual Weighing Settlement method eliminates discrepancies arising from manufacturing tolerances, dimensional variations, and material density fluctuations. This approach represents the mainstream standard in the stainless steel coil tube supply chain and is widely regarded as the fairest and most transparent pricing mechanism available.
Material & Properties
Stainless steel coil tubes are manufactured from high-grade austenitic and ferritic stainless steel grades, selected to meet stringent performance requirements across diverse industrial applications. The following materials are commonly available:
- Austenitic Grades: SUS304 (UNS S30400), SUS304L (UNS S30403), SUS316 (UNS S31600), SUS316L (UNS S31603), SUS321 (UNS S32100)
- Ferritic Grades: SUS430 (UNS S43000), SUS409 (UNS S40900)
- Super-Austenitic Grades: SUS316Ti, SUS317L (UNS S31703)
Key material properties include:
- Excellent corrosion resistance in acidic, alkaline, and chloride-containing environments
- High strength-to-weight ratio with superior formability
- Thermal stability ranging from cryogenic temperatures up to 870°C (1600°F) for austenitic grades
- Non-magnetic characteristics (austenitic grades) ensuring suitability for electromagnetic applications
- Hygienic surface finish resistant to bacterial growth (critical for food-grade applications)
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Product Form | Continuous Coil Tube (盘管) | — |
| Outer Diameter (OD) | 6.0 mm – 168.3 mm (¼" – 6") | ASTM A554 / GB/T 12771 |
| Wall Thickness (WT) | 0.3 mm – 6.0 mm | ASTM A554 / GB/T 12771 |
| Coil Inner Diameter (ID) | 400 mm – 600 mm (standard); custom available | Manufacturer Specification |
| Coil Length per Spool | 100 m – 500 m (variable) | Manufacturer Specification |
| Surface Finish | No.1 Annealed, 2B, BA (Bright Annealed), No.4 Brushed, Mirror (8K) | ASTM A480 / GB/T 4237 |
| End Condition | Plain end, beveled end, or custom per buyer requirement | Buyer Specification |
| Tolerance on OD | ±0.05 mm (precision grade); ±0.1 mm (standard grade) | ASTM A554 |
| Tolerance on WT | ±0.02 mm (precision grade); ±0.05 mm (standard grade) | ASTM A554 |
| Pricing Methodology | Actual Weighing Settlement (实际过磅结算) — Floor Scale / Hoist Scale Net Weight Measurement | Industry Standard Practice |
| Payment Basis | Measured Net Weight × Agreed Unit Price (CNY/kg or USD/MT) | Commercial Agreement |
Manufacturing Process
The production of stainless steel coil tubes follows a rigorous, multi-stage manufacturing process designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Strip Milling & Annealing: Hot-rolled stainless steel strip is cold-rolled to the required thickness and annealed to relieve residual stresses and achieve desired grain structure.
- Slitting: The cold-rolled strip is slit into precise widths corresponding to the target tube outer diameter, with edge quality optimized for seamless forming.
- Forming (Roll Forming): The strip is passed through a series of precision dies and rollers that progressively bend and shape the flat material into a tubular cross-section. This continuous process ensures uniform wall thickness and ovality control.
- Welding (if applicable): For welded coil tubes, a high-frequency induction welding (HF-W) or laser welding process joins the seam with minimal heat-affected zone, followed by in-line weld inspection.
- In-Line Annealing & Pickling: The formed tube passes through a continuous annealing furnace (typically 1050°C–1150°C) to homogenize microstructure, followed by acid pickling to remove oxide scale and restore corrosion resistance.
- Surface Finishing: Mechanical polishing, electropolishing, or chemical brightening is applied to achieve the specified surface finish grade.
- Coiling & Packaging: The finished tube is wound onto a coil core with controlled tension to prevent deformation, then wrapped in protective film and secured for transport.
- Quality Inspection & Weighing: Each coil undergoes dimensional verification, chemical composition analysis, mechanical testing, and non-destructive testing (NDT) prior to final weighing on certified floor scales or hoist scales for settlement purposes.
Applications
Stainless steel coil tubes find extensive application across numerous industries due to their corrosion resistance, mechanical strength, and hygienic properties:
- Food & Beverage Industry: Sanitary piping, brewing systems, dairy processing equipment, and food-grade conveyor systems (SUS304, SUS316L)
- Chemical & Petrochemical Industry: Process piping, heat exchanger tubes, reactor internals, and transfer lines resistant to aggressive chemical media (SUS316, SUS317L)
- Pharmaceutical Industry: CIP (Clean-In-Place) systems, bioreactor piping, and sterile fluid transfer lines (SUS316L, electropolished finish)
- Automotive Industry: Exhaust system components, fuel lines, turbocharger pipes, and structural tubing
- Construction & Architecture: Handrails, structural supports, decorative facades, and building infrastructure
- Energy Sector: Solar thermal collectors, geothermal systems, and nuclear-grade piping components
- Medical Devices: Endoscope tubing, implant-grade components, and surgical instrument shafts
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains comprehensive quality assurance systems ensuring compliance with international and national standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- EN 10204 — European Standard for Test Certificates (Type 2.2 / 3.1 available)
- ASTM / ASME — Compliance with American Society for Testing and Materials standards
- GB/T 12771 — Chinese National Standard for welded stainless steel tubes
- PED (Pressure Equipment Directive) — European conformity for pressure applications
- NSF / 3-A Sanitary Standards — Food and dairy processing compliance
Actual Weighing Settlement — Unique Selling Points
The Actual Weighing Settlement method (实际过磅结算) is the definitive pricing standard for stainless steel coil tubes, ensuring complete transparency and fairness in commercial transactions.
The following key advantages distinguish this settlement methodology:
- Elimination of Tolerance Disputes: By measuring actual net weight rather than calculating theoretical weight from nominal dimensions, all disputes arising from manufacturing tolerances (±0.05 mm OD, ±0.02 mm WT) are completely resolved. The buyer pays only for the material actually received.
- Calibrated Measurement Instruments: Settlement is performed using certified floor scales (地磅, capacity range: 10 MT – 60 MT) and calibrated hoist scales (吊秤, capacity range: 0.5 MT – 5 MT), both maintained under recognized metrological standards (JJG 539 for floor scales, JJG 581 for hoist scales).
- Real-Time Verification: Buyers or their authorized representatives may witness the weighing process in real-time, ensuring full traceability and audit capability.
- Industry Mainstream Practice: This method is the dominant and most widely accepted pricing mechanism in the stainless steel coil tube supply chain, ensuring market consistency and competitive neutrality.
- Cost Efficiency: Eliminates the need for complex tolerance adjustment calculations, reducing administrative overhead and accelerating settlement cycles.
- Documentation & Traceability: Each weighing event generates a certified weight certificate (磅单) documenting the date, time, instrument ID, operator, and measured net weight — providing a complete audit trail for both parties.
This commitment to transparent, measurement-based pricing reflects Wenzhou Jixing Metal Materials Co., Ltd's dedication to building trust-based commercial relationships with customers worldwide.