Stainless Steel Coil Tube (Coiltube) for Vessel Head Groove Applications
Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered tubular component designed for installation within the grooves of pressure vessel heads (封头盘管槽). This product category addresses the critical engineering requirement of integrating heat-transfer coil assemblies into vessel heads, ensuring reliable performance in high-pressure and high-temperature environments. The coil tube is fabricated from high-grade austenitic stainless steel and supplied in continuous coil form, enabling seamless integration into complex vessel head geometries without compromising structural integrity or thermal efficiency.
Coil tubes serve as essential elements in heat exchanger systems, reactor internals, and chemical processing vessels where efficient heat dissipation or absorption is required within confined spatial configurations. The coil tube groove (盘管槽) in the vessel head is a machined channel designed to house the coiled tubing, providing mechanical support and thermal contact with the vessel shell while maintaining a controlled fluid flow path.
Material & Properties
The coil tube is manufactured from premium-grade austenitic stainless steel, selected for its superior corrosion resistance, mechanical strength, and thermal conductivity. The primary material specifications include:
- Material Grades: SUS304 (AISI 304), SUS304L (AISI 304L), SUS316L (AISI 316L), SUS321 (AISI 321), and SUS310S (AISI 310S)
- Corrosion Resistance: Excellent resistance to pitting, crevice corrosion, and intergranular corrosion due to high chromium (Cr ≥ 18%) and nickel (Ni ≥ 8%) content
- Mechanical Properties: Tensile strength ranging from 515 MPa to 720 MPa depending on grade and condition; yield strength ≥ 205 MPa
- Thermal Properties: Thermal conductivity of 14–16 W/(m·K) at room temperature; low thermal expansion coefficient
- Operating Temperature Range: −196°C to 870°C (depending on grade selection)
- Surface Finish: 2B mill finish, No. 1 finish, or electropolished finish available; surface roughness Ra ≤ 0.8 μm
- Hygienic Compliance: Available in sanitary-grade finish meeting FDA and 3-A standards for food and pharmaceutical applications
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3 mm – 50 mm (customizable) | ASTM A213 / EN 10216-5 |
| Wall Thickness | 0.3 mm – 4.0 mm | ASTM A213 / GB/T 12771 |
| Inner Diameter (ID) | 2 mm – 46 mm (derived from OD and wall thickness) | ASTM A213 |
| Coil Inner Diameter (CID) | 50 mm – 500 mm (configurable per design) | Custom / Project Specification |
| Coil Length (Total) | 5 m – 1000 m (continuous coil) | — |
| Helix Diameter Tolerance | ±0.5 mm (standard); ±0.2 mm (precision) | ISO 286 / EN 10217-7 |
| Winding Pitch | 1.0 mm – 10.0 mm (adjustable) | Design Specification |
| Surface Roughness | Ra ≤ 0.8 μm (standard); Ra ≤ 0.4 μm (hygienic) | ASTM A240 |
| End Condition | Plain cut, beveled, threaded, or flanged | ASME B1.20.1 / DIN EN ISO 7 |
| Heat Treatment | Solution annealed (1050°C – 1150°C), water quenched | ASTM A213 |
| Non-Destructive Testing | 100% eddy current testing (ECT) or ultrasonic testing (UT) | ASTM E309 / ASME BPV Section V |
| Pressure Rating | Up to 40 MPa (PN40) depending on OD and wall thickness | ASME BPV Code / EN 13480 |
| Coating Options | None (bare), PTFE lined, or passivated | ASTM A967 |
Manufacturing Process
The manufacturing of coil tubes for vessel head groove applications follows a rigorous multi-stage process ensuring dimensional accuracy, metallurgical integrity, and surface quality:
- Material Selection and Certification: High-grade austenitic stainless steel seamless tubes or welded tubes are procured with full mill certificates (MTC) compliant with EN 10204 3.1 or 3.2. Incoming material undergoes chemical analysis (spectrometry) and mechanical property verification.
- Tube Straightening and Cutting: Raw tubes are cold-straightened to eliminate residual curvature and cut to precise lengths using high-precision sawing machines. Cut ends are deburred to prevent flow disruption and stress concentration.
- Coil Winding (Coiling): The straightened tube is wound onto a precision mandrel using a CNC-controlled coiling machine. The winding parameters — helix diameter, pitch, and number of turns — are programmed to match the vessel head groove dimensions exactly. The winding process maintains constant tension to prevent tube distortion or kinking.
- Welding and Seam Sealing: Where continuous coil length requires joining, orbital TIG (Tungsten Inert Gas) welding is employed to create full-penetration butt welds. Weld quality is verified by radiographic testing (RT) or eddy current testing (ECT) per ASME Section IX.
- Surface Treatment: The coiled tube undergoes pickling and passivation treatment using nitric acid/hydrofluoric acid solutions to remove surface contaminants and restore the chromium oxide passive layer. For hygienic applications, electropolishing is applied to achieve Ra ≤ 0.4 μm.
- Quality Inspection: Final inspection includes dimensional verification (helix diameter, pitch, total length), visual examination, pressure testing (hydrostatic at 1.5× working pressure), and non-destructive testing. Each coil is tagged with a unique identification number traceable to the batch certificate.
- Packaging and Delivery: Coils are wrapped in protective plastic film, padded with foam, and secured on wooden pallets or custom crates to prevent mechanical damage during transport.
Applications
Stainless steel coil tubes designed for vessel head groove installation find extensive application across multiple industrial sectors:
- Chemical Processing: Reactor internals, heat exchanger coil assemblies, and distillation column internals where corrosion-resistant heat transfer is critical
- Pharmaceutical and Biotechnology: Bioreactors, crystallizers, and fermentation vessels requiring hygienic-grade heat transfer surfaces compliant with cGMP standards
- Food and Beverage Industry: Pasteurization equipment, UHT (Ultra-High Temperature) processing systems, and brewing vessels where product contact surfaces must meet sanitary requirements
- Petrochemical and Oil & Gas: Process heaters, condensers, and heat recovery units operating under elevated pressure and temperature conditions
- Power Generation: Auxiliary heat exchange systems in nuclear and thermal power plants
- Heat Exchanger Manufacturing: Shell-and-coil heat exchangers, spiral heat exchangers, and custom-designed thermal management systems
- Pressure Vessel Heads: Direct installation in machined grooves of dished heads (椭圆封头), hemispherical heads (半球形封头), and torispherical heads (碟形封头) for integrated heat transfer
Unique Selling Points
- Precision Dimensional Control: CNC-controlled coiling ensures helix diameter accuracy within ±0.2 mm, guaranteeing perfect fit within vessel head grooves without excessive clearance or interference
- Customizable Geometry: Flexible configuration of OD, wall thickness, helix diameter, pitch, and total length to match specific vessel head groove designs and thermal requirements
- Full Material Traceability: Complete batch traceability from mill certificates through manufacturing to final delivery, ensuring compliance with ASME, PED, and other regulatory frameworks
- Hygienic and Corrosion-Resistant: Available in sanitary-grade finish with electropolished surface, suitable for food, pharmaceutical, and chemical applications
- Comprehensive Testing: 100% non-destructive testing (eddy current or ultrasonic), hydrostatic pressure testing, and dimensional verification for every coil produced
- Wide Material Grade Selection: Multiple stainless steel grades available to address varying corrosion, temperature, and mechanical performance requirements
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that all coil tube products meet international standards and regulatory requirements:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- ASME "U" Stamp — Authorized Manufacturer for Pressure Vessel Components
- ASME "S" Stamp — Authorized Manufacturer for Heat Exchangers
- EN 10204 3.1 / 3.2 — Material Test Certificate compliance
- PED 2014/68/EU — European Pressure Equipment Directive compliance
- CE Marking — Conformity with European health, safety, and environmental protection standards
- NSF / ANSI 61 — Drinking Water System Components certification (for food-grade applications)
- FDA 21 CFR — Food and Drug Administration compliance for food-contact materials
- GB/T 12771 — Chinese national standard for welded stainless steel tubes
Note: All specifications listed are indicative and subject to final confirmation based on project-specific requirements. Custom manufacturing to customer-drafted specifications is available upon request. Material grades, dimensions, and surface finishes can be tailored to meet specific application demands. Please consult the technical sales team for detailed quotation and specification confirmation.