Stainless Steel Coil Tube (盘管) — Technical Product Specification
Product Series: Coil Tube / Coil Pipe (盘管)
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. (温州吉兴金属材料有限公司)
Product Code: No. 1704
1. Product Overview
The Stainless Steel Coil Tube (盘管), also referred to as a Coil Heat Exchanger Tube or Coiled Pipe, is a precision-engineered tubular product formed into a continuous helical or spiral coil configuration. This product is designed for high-efficiency heat transfer applications where compact geometry and maximum surface-area-to-volume ratio are critical performance parameters. The coil tube serves as a core component in shell-and-coil heat exchangers, condensers, evaporators, and process cooling systems across multiple industrial sectors.
Unlike straight seamless or welded tubes, coil tubes exploit the inherent advantages of helical geometry — including enhanced turbulence, improved fluid mixing, reduced pressure drop at equivalent heat duty, and superior resistance to thermal stress cycling. Wenzhou Jixing Metal Materials Co., Ltd. specializes in the production of high-quality stainless steel coil tubes that meet international standards for dimensional accuracy, mechanical integrity, and corrosion resistance.
Key Design Philosophy: The coil tube geometry maximizes heat exchange efficiency within minimal footprint, making it an indispensable component in space-constrained thermal management systems.
2. Material & Properties
2.1 Available Grades
- Austenitic Stainless Steels: AISI 304 (UNS S30400), AISI 304L (UNS S30403), AISI 316 (UNS S31600), AISI 316L (UNS S31603), AISI 321 (UNS S32100), AISI 310S (UNS S31008)
- Super-Austenitic / Duplex Grades: AISI 317L (UNS S31703), 2205 Duplex (UNS S31803), 2507 Super Duplex (UNS S32750)
- Custom Alloys: Available upon request for specialized high-temperature or high-corrosion environments
2.2 Mechanical Properties (Typical — AISI 304/316, Annealed Condition)
| Property | Specification | Test Standard |
|---|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa (75 ksi) | ASTM A213 / ASTM A269 |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (30 ksi) | ASTM A213 / ASTM A269 |
| Elongation (in 50 mm / 2 in.) | ≥ 35% | ASTM A213 / ASTM A269 |
| Hardness (Rockwell B) | ≤ 95 HRB | ASTM A213 |
| Thermal Conductivity (20°C) | 16.3 W/(m·K) — 304; 14.6 W/(m·K) — 316 | ASTM A999 |
| Linear Thermal Expansion (20–800°C) | 16.0 × 10⁻⁶ /°C — 304; 17.0 × 10⁻⁶ /°C — 316 | ASTM A999 |
| Maximum Service Temperature | 870°C (304); 870°C (316); 1150°C (310S) | Manufacturer Data |
2.3 Corrosion Resistance
- Pitting Resistance: 316/316L grades offer superior resistance to chlorides (PREN ≥ 24 for 316L; ≥ 38 for 2507 Super Duplex)
- Intergranular Corrosion: Low-carbon grades (304L, 316L) with C ≤ 0.03% eliminate sensitization risk in welding heat-affected zones
- Oxidation Resistance: Continuous service up to 870°C in oxidizing atmospheres; 310S suitable for intermittent service up to 1150°C
- Stress Corrosion Cracking (SCC): Austenitic grades exhibit susceptibility in hot chloride environments; duplex and super-duplex grades recommended for such applications
2.4 Surface Finish Options
- Standard Pickled & Passivated (P&P) — Ra ≤ 0.5 μm
- Commercial Polished — Ra ≤ 0.4 μm
- Bright Annealed (BA) — Ra ≤ 0.2 μm
- Electropolished — Ra ≤ 0.1 μm (hygienic / pharmaceutical grade)
- Custom finishes available upon specification
3. Specifications
3.1 Dimensional Parameters
| Parameter | Range / Value | Notes |
|---|---|---|
| Outer Diameter (OD) | 6.35 mm – 158.75 mm (¼" – 6") | Standard and custom sizes |
| Wall Thickness (WT) | 0.5 mm – 12.7 mm (0.020" – 0.500") | Thin-wall to heavy-wall available |
| Coil Diameter (Pitch) | 50 mm – 2000 mm | Custom pitch per application |
| Number of Turns | 1 – 500+ turns | Configurable per design requirement |
| Tube Length (Uncoiled) | 1 m – 500 m (continuous coil) | Dependent on OD and pitch |
| OD Tolerance | ±0.05 mm (precision); ±0.1 mm (standard) | Per ASTM A213 / A269 |
| Wall Thickness Tolerance | ±10% (standard); ±5% (precision) | Per ASTM A213 / A269 |
| Coil Pitch Tolerance | ±1.0 mm (standard); ±0.5 mm (precision) | Manufacturing-controlled |
| End Condition | Plain end, beveled (37.5°), threaded, or flanged | Per customer drawing |
3.2 Applicable Standards
| Standard | Description |
|---|---|
| ASTM A213 / A213M | Standard Specification for Seamless Austenitic Stainless Steel Tube for High-Temperature Service |
| ASTM A269 / A269M | Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Chemical and Similar Severities of Service |
| ASME SB-316 | Specification for Seamless Austenitic Chromium-Nickel Steel Pipe |
| EN 10217-7 | Non-ferrous Metal Tubes and Pipes — Technical Delivery Conditions — Part 7: Heat-Resistant Stainless Steel Tubes |
| GB/T 14976 | Chinese National Standard for Stainless Steel Seamless Tubes for Fluid Transport |
| GB/T 13296 | Chinese National Standard for Seamless Stainless Steel Tubes for Heat Exchangers and Boilers |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Procurement: Hot-rolled stainless steel strip or seamless tube stock sourced from certified mills, with full chemical composition verification (PMI spectroscopy + wet chemical analysis).
- Coil Forming (Pipe Making):
- Seamless Route: Tube stock is drawn and mandrel-drawn to precise OD and wall thickness, then fed into a helical forming die set.
- Welded Route: Precision cold-rolled strip is roll-formed into a helical shape with longitudinal TIG (Tungsten Inert Gas) welding using a rotating torch head, followed by weld seam grinding and heat treatment.
- Heat Treatment: Solution annealing at 1040–1150°C followed by rapid water quench to achieve full austenitic microstructure, maximum corrosion resistance, and optimal mechanical properties. Stress-relief annealing at 425–550°C available for dimensional stability in precision applications.
- Pickling & Passivation: Immersion in mixed acid (HNO₃/HF) bath to remove scale and form a uniform chromium oxide passive film. Post-passivation rinse with deionized water; surface resistivity verified ≥ 10⁶ Ω·cm².
- Dimensional Inspection: CMM (Coordinate Measuring Machine) verification of coil pitch, OD, and wall thickness at multiple points along the coil length. Visual and eddy-current inspection of weld seams (for welded grade).
- End Preparation: Cutting, beveling, threading, or flange welding as specified. End faces ground flat to prevent turbulence-induced vibration.
- Final Testing & Packaging: Hydrostatic pressure testing at 1.5× working pressure (minimum 20 seconds hold), NDE (Non-Destructive Examination) per ASME Section V, and protective packaging for shipment.
4.2 Process Advantages
- Continuous coil forming eliminates butt welds along the tube length, reducing leak points and enhancing fatigue life.
- In-house forming capability enables tight pitch tolerances (±0.5 mm) without post-forming distortion.
- Post-forming heat treatment ensures uniform microstructure throughout the coiled geometry, avoiding residual stress concentrations.
5. Applications
5.1 Primary Application Sectors
| Industry | Typical Application | Key Requirement |
|---|---|---|
| Chemical Processing | Reactant preheating, product cooling, condensation | Corrosion resistance to aggressive chemicals |
| Oil & Gas | Wellhead cooling, gas dehydration, refinery heat exchangers | High-temperature/high-pressure tolerance; H₂S resistance |
| Food & Beverage | Milk pasteurization, beer cooling, CIP (Clean-in-Place) loops | Hygienic surface finish; FDA-compliant materials |
| Pharmaceutical | Process water cooling, reactor jacketing, distillation | Electropolished finish; GMP compliance |
| Power Generation | Condenser tubes, economizer coils, superheater elements | Thermal fatigue resistance; high-temperature strength |
| Marine / Offshore | Sea water coolers, ballast water systems, HVAC | Biofouling resistance; chloride pitting resistance |
| HVAC & Refrigeration | Air conditioning coils, chiller evaporators, heat pump circuits | Compact geometry; high heat transfer coefficient |
| Automotive | Brake cooling, EGR (Exhaust Gas Recirculation) coolers, battery thermal management | Lightweight; vibration resistance |
5.2 Performance Advantages of Coil Geometry
- Enhanced Heat Transfer: Secondary Dean vortex flow within the coil enhances turbulent mixing, increasing the heat transfer coefficient by 15–40% compared to straight tubes at equivalent Reynolds numbers.
- Compact Footprint: Up to 500 m of tube length accommodated within a diameter of 2 m, ideal for space-limited installations.
- Thermal Stress Accommodation: Helical geometry provides inherent flexibility to absorb thermal expansion/contraction without additional expansion joints.
- Reduced Pressure Drop: Lower friction factor at equivalent heat duty due to favorable flow distribution in helical geometry.
- Fouling Resistance: Enhanced turbulence promotes self-cleaning action, reducing fouling accumulation on tube surfaces.
6. Quality Certifications & Compliance
6.1 Factory Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management System
- ASME "S" Stamp — Authorized Manufacturer for Pressure Vessel Components
- PED 2014/68/EU — European Pressure Equipment Directive Compliance
- EN 10204 3.1 — Third-party inspection certificates available upon request
6.2 Inspection & Testing Protocol
- Incoming Material Inspection: Certificate of Analysis (COA) verification; PMI (Positive Material Identification) spectroscopic analysis of each heat lot.
- In-Process Inspection: Dimensional checks at forming station; weld seam visual inspection; ultrasonic testing (UT) of welds per ASME Section V, Article 4.
- Final Product Testing:
- Hydrostatic pressure test — 1.5 × design pressure, minimum 20-second hold, no leakage or visible deformation
- Eddy current testing (ECT) — 100% coverage of weld seam (welded grade) per ASTM E309
- Corrosion testing — Pitting resistance index (PREN) verification; salt spray test (ASTM B117) ≥ 5