Stainless Steel Coil Tube (Coil Pipe) – Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a continuous-length hollow profile produced in coil form, designed for downstream processing such as cutting, bending, welding, and forming. Coil tubes offer significant advantages over straight-length pipe in terms of material utilization, logistics efficiency, and processing flexibility. The product is engineered to meet stringent dimensional tolerances, surface finish requirements, and mechanical property standards applicable across industrial, energy, and infrastructure sectors.
This product line integrates advanced Manufacturing Execution System (MES) management, ensuring full traceability from raw material receipt through final dispatch. The MES framework enables real-time monitoring of production parameters, quality checkpoints, and process deviations, thereby guaranteeing consistent product performance and compliance with international standards.
2. Material & Properties
2.1 Common Grade Designations
- AISI 304 / 1.4301 – General-purpose austenitic stainless steel with excellent corrosion resistance and formability.
- AISI 316 / 1.4401 – Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion in aggressive environments.
- AISI 316L / 1.4404 – Low-carbon variant of 316, suitable for welding applications requiring reduced sensitization risk.
- AISI 321 / 1.4541 – Titanium-stabilized grade with enhanced resistance to intergranular corrosion at elevated temperatures.
- AISI 304L / 1.4307 – Low-carbon grade optimized for weldability and cryogenic service.
2.2 Mechanical Properties (Typical Values – Annealed Condition)
| Property | Unit | Typical Value | Standard Reference |
|---|---|---|---|
| Tensile Strength (Rm) | MPa | ≥ 520 (304), ≥ 515 (316) | ASTM A270 / EN 10216-5 |
| Yield Strength (Rp0.2) | MPa | ≥ 205 (304), ≥ 170 (316) | ASTM A270 / EN 10216-5 |
| Elongation (A) | % | ≥ 40 | ASTM A270 |
| Hardness (HV 30) | HB | ≤ 200 (annealed) | ISO 6507 |
| Density | g/cm³ | 7.93 (304), 8.00 (316) | — |
| Thermal Conductivity (at 100°C) | W/(m·K) | 16.3 (304), 14.6 (316) | ASTM E153 |
| Maximum Service Temperature | °C | 870 (304), 870 (316) | ASTM A270 |
2.3 Corrosion Resistance Characteristics
- Excellent resistance to atmospheric, freshwater, and mild alkaline environments.
- 316/316L grades provide enhanced resistance to chlorides, acids, and marine atmospheres.
- Passive oxide layer (Cr₂O₃) self-heals in the presence of oxygen, maintaining long-term corrosion protection.
3. Specifications
| Parameter | Specification Range | Applicable Standard |
|---|---|---|
| Outer Diameter (OD) | Φ6.0 mm – Φ168.3 mm | ASTM A270 / EN 10216-5 |
| Wall Thickness (WT) | 0.5 mm – 6.0 mm | ASTM A270 / EN 10216-5 |
| OD Tolerance | ±0.05 mm (precision) / ±0.10 mm (standard) | ISO 8494 |
| WT Tolerance | ±0.03 mm (precision) / ±0.06 mm (standard) | ISO 8494 |
| Coil Length (Continuous) | Up to 10,000 m (spooled) | Enterprise Standard |
| Coil Inner Diameter | Φ250 mm / Φ450 mm / Φ500 mm | Enterprise Standard |
| End Form | Plain end / Beveled end (as per customer specification) | — |
| Surface Finish | 2B (Cold Rolled & Annealed) / BA (Bright Annealed) / No. 4 Hairline | ASTM A480 |
| Surface Roughness (Ra) | ≤ 0.4 µm (BA) / ≤ 0.8 µm (2B) / ≤ 1.6 µm (No.4) | ISO 4287 |
| Heat Treatment | Annealed (Solution Annealed at 1010–1150°C, followed by controlled cooling) | ASTM A270 |
| Delivery Condition | Coiled / Straight lengths (cut-to-length available) | — |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Procurement & Inspection – Stainless steel strip (cold-rolled) is received with full mill certificates (MTC) and subjected to incoming inspection including chemical composition analysis (OES), dimensional verification, and surface quality assessment.
- Strip Coiling & Slitting – The strip is slit to the required width and recoiled for the pipe forming stage.
- Pipe Forming (Cold Forming) – Using a roll-forming mill or ERW (Electric Resistance Welded) / TP (Transverse Pulse) welding technology, the flat strip is formed into a tubular shape. The coil tube process allows continuous, high-speed production.
- Welding (if applicable) – For welded coil tubes, high-frequency induction or transverse pulse welding is employed to create a strong, defect-free weld seam. Weld parameters are continuously monitored and logged via the MES system.
- Heat Treatment (Annealing) – The formed tube is solution-annealed in a continuous annealing furnace (CAF) under controlled atmosphere (argon or dew-point-controlled hydrogen) to relieve residual stresses, restore ductility, and promote full recrystallization.
- Pickling & Passivation – Surface scale and discoloration are removed via acid pickling (nitric/hydrofluoric acid blend), followed by passivation treatment to restore the protective chromium oxide layer.
- Stretching & Straightening – A stretch-bending operation is applied to improve dimensional accuracy (roundness, straightness) and enhance surface quality.
- Coiling – The finished tube is wound onto a coil spool at controlled tension to prevent deformation.
- Final Inspection & Testing – Dimensional inspection, hydrostatic pressure testing, eddy current testing (ECT) for weld seam integrity, and surface inspection are performed.
- Packaging & Dispatch – Coils are wrapped with protective film, secured with steel strapping, and packaged for export or domestic delivery.
4.2 MES-Integrated Production Management
A key differentiator of this product line is the deployment of an enterprise-level Manufacturing Execution System (MES), which provides:
- Real-time Process Monitoring – Continuous data acquisition from forming, welding, and annealing stations, enabling immediate detection and correction of deviations.
- Full Traceability – Each coil is assigned a unique batch identifier linked to raw material heat numbers, process parameters, inspection results, and operator records.
- Quality Gate Control – Automated pass/fail decisions at critical checkpoints based on predefined specification limits.
- Performance Analytics – Yield rate tracking, defect Pareto analysis, and continuous improvement (Kaizen) metrics.
- Documented Compliance – Digital records supporting audit trails for customer quality assurance and regulatory requirements.
5. Applications
5.1 Primary Application Sectors
- Chemical & Petrochemical Industry – Process piping, heat exchanger tubes, reactor internals, and transfer lines where corrosion resistance is critical.
- Food & Beverage Processing – Sanitary-grade piping systems, CIP (Clean-in-Place) compatible coils for dairy, brewing, and pharmaceutical applications.
- Automotive Industry – Exhaust system components, fuel lines, and structural tubing for lightweighting initiatives.
- Energy Sector – Solar thermal collectors, geothermal heat exchangers, and nuclear-grade applications (316L).
- Construction & Architecture – Decorative railings, structural supports, and facade elements.
- Medical Equipment – Surgical instrument tubing, hospital gas piping, and imaging equipment housings.
- Marine & Offshore – Seawater cooling systems, ballast piping, and deck fittings (316/316L grades).
5.2 Downstream Processing Compatibility
- Excellent cold-formability for bending, pressing, and deep drawing.
- Weldable in all common configurations (TIG, MIG, resistance, laser) without preheating.
- Compatible with machining, laser cutting, and waterjet cutting operations.
6. Quality Certifications & Standards Compliance
6.1 Applicable Standards
| Standard | Scope |
|---|---|
| ASTM A270 / A270M | Austenitic Stainless Steel Seamless, Welded, and Heavy-Walled Pipe, Tube, and Fittings |
| ASTM A554 / A554M | Stainless Steel Welded Austenitic Tubing for Industrial Applications |
| EN 10216-5 | Non-alloy, Heat Resistant and Stainless Steel Tubes for Pressure Purposes |
| ISO 8494 | Basic Dimensional Series for Hollow Profiles |
| JIS G3459 | Stainless Steel Tubes for General Purposes |
| GB/T 12771 | Stainless Steel Tubes for General Purposes (Chinese National Standard) |
6.2 Quality Assurance Certifications
- ISO 9001:2015 – Quality Management System certification ensuring consistent product quality and customer satisfaction.
- ISO 14001:2015 – Environmental Management System demonstrating commitment to sustainable manufacturing practices.
- ISO 45001:2018 – Occupational Health & Safety Management System.
- EN 10204 3.1 / 3.2 – Inspection Certificate / Third-party Inspection Certificate available upon request.
- Mill Test Certificate (MTC) – Provided with every shipment, detailing chemical composition, mechanical properties, and heat treatment condition.
6.3 Inspection & Testing Methods
- Chemical Analysis – Optical Emission Spectroscopy (OES) and Combustion Analysis (C, N) per ASTM E415 / E1019.
- Mechanical Testing – Tensile testing (ASTM A370), hardness testing (ISO 6507).
- Non-Destructive Testing (NDT) – Eddy Current Testing (ECT) for weld seam integrity (ISO 16884); Hydrostatic testing for leak-tightness (ASTM A270).
- Dimensional Inspection – Optical measurement systems and laser micrometers for OD, WT, and roundness verification.
- Surface Inspection – Visual and automated surface scanning for defects, pitting, or inclusions.
- Intergranular Corrosion Testing – ASTM A262 Practice E (for stabilized grades).
7. Unique Selling Points
Wenzhou Jixing Metal Materials Co., Ltd. distinguishes its stainless steel coil tube product line through the following competitive advantages:
- MES-Driven Process Excellence – Industry-leading digital manufacturing execution ensures full production transparency, real-time quality control, and comprehensive traceability from raw material to finished product.
- Wide Range of Grades & Dimensions – Comprehensive catalog covering standard and specialty austenitic grades with precise dimensional control down to ±0.03 mm wall thickness tolerance.
- Superior Surface Quality – Bright Annealed (BA) and precision 2B finishes achieving Ra values as low as 0.4 µm, suitable for hygienic and decorative applications.
- High Material Utilization – Coil form eliminates cut-off waste, reducing material loss by up to 8–12% compared to straight-length pipe procurement.
- Flexible Logistics & Inventory – Continuous coil delivery optimizes shipping efficiency and reduces storage footprint for end-users.
- Customization Capability – Tailored specifications for wall thickness, surface finish, coil diameter, and special testing protocols available upon request.
- Global Compliance – Products certified to multiple international standards, facilitating seamless integration into global supply chains.
8. Packaging & Delivery
- Coils are wrapped with moisture-proof PE film and secured with galvanized steel strapping