Stainless Steel Coil Tube — General Tolerance Grade (OD ±1%, WT ±10%)
1. Product Overview
The Stainless Steel Coil Tube (盘管 / Coil Tube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a seamless or welded stainless steel tube supplied in coiled form, designed for high-volume processing applications where downstream forming, bending, and cutting operations demand consistent dimensional accuracy. This product falls under the General Tolerance Grade (普通级), adhering to the default tolerance specifications defined by GB/T 14976 (Chinese National Standard) and ASTM A269 (American Society for Testing and Materials Standard), which are the two most widely recognized international standards for cold-drawn seamless stainless steel tubing.
The General Tolerance Grade represents the standard production tolerance class, balancing manufacturing efficiency with dimensional reliability. This grade is suitable for the vast majority of industrial applications where extreme precision is not mandated but where consistent quality and compliance with recognized international standards are essential.
2. Material & Properties
2.1 Available Material Grades
- Austenitic Grades: 304 (UNS S30400), 304L (UNS S30403), 316 (UNS S31600), 316L (UNS S31603), 321 (UNS S32100), 310S (UNS S31008)
- Duplex Grades: 2205 (UNS S31803), 2507 (UNS S32750)
- Custom Grades: Available upon request in accordance with ASTM, EN, JIS, or GB specifications
2.2 Key Mechanical & Physical Properties (Typical for Grade 304)
- Tensile Strength: ≥ 515 MPa (75 ksi)
- Yield Strength: ≥ 205 MPa (30 ksi)
- Elongation: ≥ 40% (in 50 mm / 2 in.)
- Corrosion Resistance: Excellent resistance to atmospheric, chemical, and food-grade environments
- Temperature Range: −196 °C to +870 °C (−321 °F to +1,598 °F)
- Surface Finish: Bright annealed, pickled, polished, or custom finishes available
3. Specifications
3.1 Geometric Parameters — General Tolerance Grade
| Parameter | Specification | Governing Standard | Remarks |
|---|---|---|---|
| Outer Diameter (OD) Tolerance | ±1% of nominal OD | GB/T 14976 / ASTM A269 | Default general tolerance grade; applies to all nominal OD sizes |
| Wall Thickness (WT) Tolerance | ±10% of nominal WT | GB/T 14976 / ASTM A269 | Default general tolerance grade; accommodates manufacturing variability |
| Coil Inner Diameter (Coil ID) | 100 – 300 mm (typical) | Customizable | Adaptable to customer processing equipment |
| Coil Outer Diameter (Coil OD) | Up to 1,200 mm | Customizable | Determined by tube size and coil weight requirements |
| Nominal OD Range | 1 – 150 mm | GB/T 14976 / ASTM A269 | Seamless and welded configurations available |
| Nominal WT Range | 0.2 – 12 mm | GB/T 14976 / ASTM A269 | Thin-wall and heavy-wall options |
| Coil Weight | Up to 3,000 kg per coil | — | Optimized for logistics and handling efficiency |
| Tube Length per Coil | Continuous (spooled) | — | Eliminates butt welds; enables high-throughput processing |
| End Condition | Plain cut, beveled, or threaded | Per customer drawing | Customized to downstream application |
| Surface Condition | Pickled & passivated, bright annealed, or polished | ASTM A967 / GB/T 4237 | Anti-corrosion surface treatment included |
3.2 Tolerance Comparison — General Grade vs. Tighter Grades
| Tolerance Grade | OD Tolerance | WT Tolerance | Typical Application |
|---|---|---|---|
| General (普通级) | ±1% | ±10% | General industrial piping, structural uses, food processing |
| Tight (精密级) | ±0.5% | ±6% | Hydraulic systems, medical devices, instrumentation |
| Ultra-Precision (高精度级) | ±0.2% | ±3% | Aerospace components, semiconductor equipment |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Selection: High-purity stainless steel billet or strip sourced from certified mills, with full chemical composition verification via spectroscopic analysis (OES / XRF).
- Hot Rolling or Welding: Billets are hot-rolled into seamless tube blanks, or precision strip is welded via Automatic Welding (AW) / Electron Beam Welding (EBW) for welded coil tube.
- Cold Drawing / Cold Pilgering: Tube blanks are cold-drawn through precision dies to achieve the target OD and WT within General Tolerance specifications (OD ±1%, WT ±10%).
- Intermediate Annealing: Periodic annealing cycles relieve work-hardening, restore ductility, and stabilize microstructure during multi-pass drawing operations.
- Final Dimensional Verification: Each coil undergoes automated OD and WT gauging at multiple points along its length using ultrasonic thickness measurement and laser OD scanners.
- Surface Treatment: Pickling and passivation (per ASTM A967) remove scale and form a protective chromium oxide layer; optional electropolishing or mechanical polishing available.
- Coiling: Tubes are coiled onto precision pay-off reels at controlled tension to prevent deformation, kinking, or ovality.
- Non-Destructive Testing (NDT): Eddy current inspection (per ASTM E309) ensures internal and external surface integrity; hydrostatic testing (per ASTM A269) verifies pressure containment.
- Final Inspection & Packaging: Visual inspection, dimensional re-verification, and protective packaging (wooden crates, steel banding, desiccant inserts) for shipment.
4.2 Quality Control Milestones
| Stage | Inspection Method | Acceptance Criteria |
|---|---|---|
| Raw Material | Spectroscopic Analysis (OES) | Chemical composition within ASTM / GB grade limits |
| In-Process Drawing | Ultrasonic Thickness + Laser OD Gauge | OD within ±1%, WT within ±10% of nominal |
| Post-Annealing | Rockwell Hardness Testing | Hardness ≤ 95 HRB (annealed condition) |
| Final Product | Eddy Current (ASTM E309) + Hydrostatic Test | No defects; pressure hold ≥ 10 sec without leakage |
| Surface | Visual + Ra Roughness Measurement | No pitting, cracks, or scale; Ra ≤ 0.4 μm (polished) |
5. Applications
The General Tolerance Grade Stainless Steel Coil Tube is engineered for broad industrial deployment where dimensional consistency is required without the premium cost of tighter tolerance grades. Key application domains include:
- Food & Beverage Processing: Sanitary piping systems, CIP (Clean-in-Place) circuits, dairy and brewery equipment — Grade 304/316L coil tubes enable seamless, hygienic installations with minimal crevice risk.
- Pharmaceutical Manufacturing: Process piping for GMP-compliant facilities, requiring corrosion-resistant, cleanable tubing with reliable dimensional conformity.
- Chemical & Petrochemical Industry: Transfer lines, heat exchanger tubes, and reactor feed systems where resistance to aggressive media is paramount.
- Automotive & Machinery: Exhaust system components, fuel lines, and hydraulic circuit tubing where coil form factor reduces material waste and fabrication time.
- Construction & Architecture: Structural tubing for railings, handrails, and decorative elements where aesthetic finish and corrosion resistance are valued.
- Medical Device Manufacturing: Feed stock for downstream machining of instrument handles, endoscope shafts, and surgical tool components.
- Heat Exchanger Manufacturing: Coil tubes pre-formed for U-tube and shell-and-tube heat exchangers, where continuous coil form eliminates butt welds and improves thermal efficiency.
6. Quality Certifications & Compliance
6.1 Standards Compliance
- GB/T 14976 — Technical conditions for cold-drawn seamless stainless steel tubes (Chinese National Standard)
- ASTM A269 / A269M — Standard specification for austenitic stainless steel seamless, welded, and heavily cold-worked tubing and pipe
- ASTM A967 — Standard practice for chemical cleaning and passivation of stainless steel parts
- ASTM E309 — Standard practice for eddy current testing of austenitic stainless steel tubing and pipe
- EN 10217-7 — Technical delivery conditions for seamless stainless steel tubes for general purposes
- ISO 9001:2015 — Quality Management System certification
6.2 Certificates Provided with Each Shipment
| Certificate Type | Content | Standard Reference |
|---|---|---|
| Mill Test Certificate (MTC / EN 10204 3.1) | Chemical composition, mechanical properties, heat number traceability | EN 10204 Type 3.1 |
| NDT Inspection Report | Eddy current and hydrostatic test results | ASTM E309 / ASTM A269 |
| Dimensional Inspection Report | OD and WT measurement data at multiple sample points | GB/T 14976 / ASTM A269 |
| Material Traceability Certificate | Heat number, lot tracking, origin documentation | ISO 9001:2015 |
7. Unique Selling Points
- International Dual-Standard Compliance: Every coil tube is manufactured and verified against both GB/T 14976 and ASTM A269, ensuring global market acceptance without re-inspection or re-certification delays.
- Optimized Cost-to-Performance Ratio: The General Tolerance Grade delivers reliable dimensional accuracy (OD ±1%, WT ±10%) at a competitive price point, making it the most cost-effective choice for high-volume procurement.
- Continuous Coil Form Factor: Eliminates butt welds inherent in bar-length supply, reducing material waste by up to 15% and enabling automated cut-to-length processing with minimal operator intervention.
- Full Traceability: Each coil is linked to its heat number, enabling end-to-end material traceability from mill origin to final installation — critical for regulated industries (pharmaceutical, food, medical).
- Comprehensive NDT Coverage: Eddy current inspection (ASTM E309) and hydrostatic pressure testing are performed on 100% of coils, ensuring zero-defect delivery.
- Flexible Configuration: Custom OD, WT, coil diameter, surface finish, and end-condition options available to match specific customer processing equipment and application requirements.
- Established Manufacturing Heritage: Wenzhou Jixing Metal Materials Co., Ltd leverages decades of expertise in stainless steel tube production, backed by ISO 9001:2015 certified quality systems and a proven track record of on-time, on-spec delivery.
8. Ordering & Customization Guidance
Note: Customers requiring tolerances tighter than the General Grade (OD ±1%, WT ±10%) should consult the technical sales team for quotation on Tight Tolerance Grade (OD ±0.5%, WT ±6%) or Ultra-Precision Grade (OD ±0.2%, WT ±3%). Lead times, pricing, and minimum order quantities vary by tolerance class and material grade. All custom specifications must be confirmed in writing via a signed technical agreement prior to production commencement.