Stainless Steel Coil Tube (Coil Pipe) — Industrial Process & Heat Exchanger Application
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product formed through continuous coiling technology. Designed for high-performance applications in heat exchangers, chemical processing, petroleum refining, and single-well coil furnace systems, this product combines superior corrosion resistance, mechanical integrity, and thermal conductivity. The coil tube is produced in continuous spool configurations, enabling efficient downstream processing such as bending, welding, and direct installation into complex heat-transfer geometries.
Particularly notable is the product's application in single-well coil furnace retrofit designs (单井盘管炉改造设计), where the coil tube serves as the critical heat-exchange element within vertical furnace wells. The retrofit design study demonstrates how optimized coil tube geometry, material selection, and layout significantly improve thermal efficiency, reduce pressure drop, and extend operational service life in high-temperature process environments.
Material & Properties
The coil tube is fabricated from high-grade austenitic and duplex stainless steels, selected to meet the demanding requirements of aggressive chemical and thermal environments. Common material grades include:
- 304 / 304L (UNS S30400 / S30403) — General-purpose corrosion resistance with excellent formability
- 316L (UNS S31603) — Enhanced pitting and crevice corrosion resistance due to molybdenum addition
- 321 (UNS S32100) — Stabilized against intergranular corrosion at elevated temperatures
- 310S (UNS S31008) — High-temperature strength up to 1100°C, suitable for furnace applications
- Super Duplex 2507 (UNS S32750) — High yield strength with superior resistance to chloride stress corrosion cracking
Key Mechanical Properties
- Yield Strength: 205–550 MPa (depending on grade)
- Tensile Strength: 515–800 MPa
- Elongation: ≥35% (minimum)
- Operating Temperature Range: −196°C to +1100°C (grade-dependent)
Chemical Composition (Typical — Grade 316L)
| Element | Minimum (%) | Maximum (%) |
|---|---|---|
| Carbon (C) | — | 0.030 |
| Chromium (Cr) | 16.5 | 18.5 |
| Nickel (Ni) | 10.0 | 14.0 |
| Molybdenum (Mo) | 2.0 | 3.0 |
| Manganese (Mn) | — | 2.0 |
| Silicon (Si) | — | 1.0 |
| Phosphorus (P) | — | 0.045 |
| Sulfur (S) | — | 0.030 |
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Catalog No. | 1127 |
| Outer Diameter (OD) | Φ6 mm — Φ159 mm |
| Wall Thickness | 0.3 mm — 6.0 mm |
| Coil Inner Diameter (CID) | Φ400 mm — Φ1200 mm |
| Coil Length (Continuous) | 500 m — 5000 m (spool) |
| Surface Finish | 2B / BA (Bright Annealed) / Pickled & Passivated |
| Manufacturing Standard | ASTM A213 / ASTM A269 / EN 10216-5 / GB/T 12771 |
| Material Grades | 304, 304L, 316, 316L, 321, 310S, 2205, 2507 |
| End Condition | Open end / Sealed end / Beveled / Threaded |
| Acceptable Tolerance | OD: ±0.15 mm; Wall: ±10% (or per customer spec) |
| Packaging | Wooden crate / Steel banding / Export-grade protective wrapping |
Manufacturing Process
The production of high-quality stainless steel coil tubes involves a multi-stage manufacturing sequence designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Hot Rolling / Casting: Stainless steel slabs or billets are produced via Continuous Casting (CC) or ladle refining, ensuring uniform chemical composition and minimal inclusions.
- Hot Rolling to Blank: The slab is hot-rolled into flat strip or round bar stock to approximate the target coil tube dimensions.
- Pierling & Cold Drawing: For seamless coil tube, the billet is hot-pierled into hollow stock, followed by cold drawing through precision dies to achieve final OD and wall thickness tolerances.
- Continuous Coiling: The drawn tube is wound onto a coil former at controlled tension to produce the continuous coil configuration. Tension control ensures uniform wall thickness along the coil length.
- Solution Annealing: The coil tube is heat-treated at 1050–1150°C followed by rapid quenching (air or water) to dissolve carbides and restore full austenitic microstructure, maximizing corrosion resistance.
- Pickling & Passivation: The tube surface is cleaned of oxide scale via acid pickling (nitric/hydrofluoric acid blend) and passivated with dilute nitric acid to form a protective chromium oxide film.
- Hydrostatic / Eddy Current Testing: Every coil spool undergoes 100% non-destructive testing (NDT) to verify wall integrity and detect subsurface defects.
- Final Inspection & Packaging: Dimensional verification, surface quality assessment, and material certification documentation precede protective packaging for shipment.
Applications
The Stainless Steel Coil Tube is widely deployed across multiple high-performance industrial sectors:
- Single-Well Coil Furnace Systems (单井盘管炉): The coil tube serves as the primary heat-exchange element in vertical furnace wells for petroleum cracking, hydrogen production, and naphtha reforming. Retrofit design studies have demonstrated that optimized coil tube configuration significantly improves radiant heat absorption efficiency and reduces hot-spot degradation.
- Chemical Processing: Reactor internals, heat exchanger bundles, and process piping in aggressive acid/alkali environments.
- Petrochemical & Refining: Crude distillation column internals, reboilers, and transfer lines.
- Power Generation: Boiler tubes, superheaters, and economizers in combined-cycle gas turbines (CCGT) and nuclear power plants.
- Food & Pharmaceutical: Sanitary-grade heat exchangers and process tubing meeting FDA and EHEDG standards.
- Heat Exchanger Manufacturing: Air-cooled heat exchanger (ACHE) bundles, spiral wound gaskets, and compact heat transfer surfaces.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality assurance systems to ensure product conformity with international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001 — Environmental Management System
- ASTM International — Compliance with ASTM A213 (seamless austenitic stainless steel tube for high-temperature service) and ASTM A269 (austenitic stainless steel tubing for general use)
- EN 10216-5 — European standard for seamless austenitic stainless steel tubes
- GB/T 12771 — Chinese national standard for austenitic stainless steel seamless tubes
- Mill Test Certificates (MTC) — EN 10204 3.1 certification provided with every shipment
- Third-Party Inspection — Available upon request (SGS, Bureau Veritas, DNV, Lloyd's Register)
Unique Selling Points
- Continuous Spool Configuration: Eliminates field welding joints, reducing potential leak points and maintenance costs in heat exchanger and furnace applications.
- Single-Well Coil Furnace Optimization: Drawing from retrofit design engineering experience, the coil tube geometry is optimized for maximum heat transfer surface area per unit volume within constrained furnace well dimensions.
- Grade Flexibility: Wide range of material grades available, from general-purpose 304L to ultra-high-temperature 310S and high-strength Super Duplex 2507, enabling tailored solutions for specific process conditions.
- Precision Dimensional Control: Advanced cold-drawing and coiling technology ensures tight tolerances (±0.15 mm OD), critical for press-fit heat exchanger tube sheet installations.
- 100% NDT Coverage: Every coil spool is fully tested via hydrostatic pressure and eddy current methods, ensuring zero-defect delivery.
- Full Traceability: Each coil is accompanied by a complete material traceability chain from melt heat number to final inspection report, supporting regulatory compliance in nuclear, aerospace, and pharmaceutical applications.
Note: The design and specification of coil tubes for single-well furnace applications should account for thermal expansion, sag under load, and flow-induced vibration (FIV). Wenzhou Jixing Metal Materials Co., Ltd. offers engineering consultation for custom coil configurations tailored to specific furnace geometry and process parameters.