Stainless Steel Coil Tube (Spiral Wound Coil Tube) — Model No. 1437

1. Product Overview

The Stainless Steel Coil Tube (product designation: Coiltube, serial number 1437) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular product designed primarily for use in shell-and-tube spiral coil heat exchangers and other thermal management systems. This product represents a high-performance solution that combines the mechanical integrity of stainless steel with the geometric efficiency of a continuously wound spiral configuration, delivering superior heat transfer performance, compact footprint, and long service life under demanding industrial conditions.

The spiral coil tube is formed by winding a seamless stainless steel pipe into a helical or planar spiral geometry, creating a single continuous tube with a large surface-area-to-volume ratio. This configuration is particularly advantageous in applications requiring high heat exchange efficiency within space-constrained environments, such as petrochemical processing, power generation, food and beverage pasteurization, and HVAC systems.

2. Material Composition & Properties

The coil tube is fabricated from austenitic stainless steel grades that meet or exceed international standards for chemical composition, mechanical properties, and corrosion resistance. The following are the typical material specifications:

2.1 Common Grades

• 304 / 304L (UNS S30400 / S30403): The most widely used austenitic stainless steel, offering excellent general corrosion resistance, weldability, and formability. Suitable for food-grade, chemical processing, and general industrial applications.
• 316L (UNS S31603): Enhanced resistance to pitting and crevice corrosion due to molybdenum (Mo) addition. Ideal for marine environments, chemical processing, and pharmaceutical applications.
• 321 (UNS S32100): Stabilized with titanium (Ti), providing superior resistance to intergranular corrosion at elevated temperatures. Suitable for high-temperature heat exchanger applications.
• 310S (UNS S31008): High-temperature austenitic grade with excellent oxidation resistance up to 1150°C, used in extreme thermal environments.

2.2 Mechanical Properties (Typical for Grade 304)

• Tensile Strength (R_m): ≥ 520 MPa
• Yield Strength (R_p0.2): ≥ 205 MPa
• Elongation (A_50mm): ≥ 40%
• Hardness (HBW): ≤ 217
• Operating Temperature Range: −196°C to +870°C (non-oxidizing atmosphere)

3. Technical Specifications

Technical Specifications — Stainless Steel Coil Tube (Model 1437)

Parameter	Specification	Standard Reference
Outer Diameter (OD)	Φ6.0 mm – Φ50.8 mm (customizable)	EN 10217-7 / ASTM A213
Wall Thickness	0.5 mm – 3.0 mm	EN 10217-7 / ASTM A269
Spiral Coil Pitch	10 mm – 80 mm (adjustable per design)	GB/T 20950 / ASME PCC-1
Spiral Coil Diameter	Φ100 mm – Φ2000 mm	Project-specific
Tube Length (Total Unwound)	Up to 300 m (continuous)	—
End Preparation	Plain end, beveled end, or threaded end	ASME B31.3
Surface Finish	Pickled & Passivated (Ra ≤ 0.8 μm)	ASTM A967
Tolerance on OD	±0.1 mm (per EN 10217-7)	EN 10217-7
Tolerance on Wall Thickness	±10% of nominal	EN 10217-7
Pressure Rating	Up to 40 bar (design-dependent)	ASME BPV Section VIII
Winding Direction	Left-hand (LH) or Right-hand (RH)	Per customer specification
Heat Treatment	Solution annealed at 1040–1120°C, followed by water quench	ASTM A213

4. Manufacturing Process

The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing process to ensure dimensional accuracy, metallurgical integrity, and surface quality:

1. Raw Material Procurement & Inspection: Seamless stainless steel pipes are sourced from certified mills and subjected to incoming inspection including chemical analysis (spectrometry), mechanical testing, and dimensional verification in accordance with ASTM E10 / E29.
2. Cold Drawing / Cold Forming: The base pipe is cold-drawn to achieve precise outer diameter and wall thickness tolerances while enhancing mechanical properties through work hardening.
3. Spiral Winding (Coiling): The formed pipe is wound into a spiral coil configuration using CNC-controlled coiling machines. The winding process is performed at controlled tension to prevent ovalization, wrinkling, or plastic deformation. Critical process parameters include winding speed, tension control, and die geometry.
4. Heat Treatment (if required): Depending on the grade and application, the coil may undergo solution annealing to relieve residual stresses and restore full austenitic microstructure.
5. Pickling & Passivation: The coil tube is subjected to acid pickling (typically nitric-hydrofluoric acid mixture) followed by passivation treatment to remove scale, contaminants, and chromium-depleted layers, restoring the protective chromium oxide passive film per ASTM A967.
6. Non-Destructive Testing (NDT): 100% visual inspection, dimensional verification, and hydrostatic pressure testing are performed. Optional NDT methods include eddy current testing (ECT) and radiographic testing (RT) for weld integrity.
7. End Finishing & Packaging: Tube ends are prepared to specification (beveled, threaded, or plain). Each coil is individually packaged with protective wrapping, desiccants, and proper labeling to prevent corrosion and mechanical damage during transit.

5. Applications

The stainless steel coil tube is widely utilized across multiple industrial sectors due to its exceptional combination of thermal performance, corrosion resistance, and mechanical durability:

• Shell-and-Tube Heat Exchangers: Primary application per GB/T 20950 (Steel Shell-and-Tube Spiral Coil Heat Exchangers), serving as the heat transfer element in process heating, cooling, condensation, and evaporation systems.
• Petrochemical & Refinery: Crude oil fractionation, catalytic cracking heat recovery, and process stream temperature control.
• Power Generation: Feedwater heaters, economizers, air preheaters, and waste heat recovery systems in thermal and combined-cycle power plants.
• Food & Beverage Industry: Pasteurization, sterilization, and thermal processing equipment (304L/316L grades for food-grade compliance).
• Pharmaceutical & Biotechnology: Clean-in-place (CIP) compatible heat exchangers for aseptic processing and bioreactor temperature control.
• Marine & Offshore: Seawater cooling systems, condensers, and heat recovery units where 316L grade provides superior chloride resistance.
• HVAC & Refrigeration: Chiller evaporators, condensers, and thermal storage systems.
• Environmental & Waste Treatment: Flue gas heat recovery, wastewater heat exchange, and scrubber systems.

6. Quality Certifications & Compliance

Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications and compliances:

• ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control.
• ISO 14001:2015 — Environmental Management System certification for sustainable manufacturing practices.
• ISO 45001:2018 — Occupational Health and Safety Management System.
• ASME "S" Stamp — Authorization for the manufacture of pressure-containing components per ASME Boiler and Pressure Vessel Code (BPVC) Section VIII.
• CE Marking (PED 2014/68/EU) — Compliance with the European Pressure Equipment Directive for products intended for the European Economic Area.
• TÜV / DNV Certification — Third-party verification for marine and offshore applications.
• EN 10204 3.1 / 3.2 Certificates — Full material and process traceability documentation with independent third-party inspection available upon request.
• Material Test Reports (MTR): Every batch is accompanied by a full material test report including chemical composition (PMI), mechanical test results, heat treatment records, and NDT documentation.

7. Unique Selling Points

Superior Heat Transfer Efficiency: The continuous spiral geometry maximizes the heat transfer surface area within a compact envelope, achieving up to 30% higher heat transfer coefficient compared to conventional straight-tube designs.

Single Continuous Tube Design: Eliminates inter-tube weld joints, significantly reducing leakage risk and improving long-term reliability in high-pressure and corrosive environments.

Exceptional Corrosion Resistance: Austenitic stainless steel grades provide outstanding resistance to general corrosion, pitting, crevice corrosion, and intergranular corrosion, ensuring service life exceeding 20 years in aggressive media.

Customizable Geometry: Spiral pitch, coil diameter, and tube dimensions are fully customizable to meet specific thermal-hydraulic design requirements, enabling optimal integration into existing heat exchanger shells.

Full Traceability & Certification: Complete material and manufacturing traceability with internationally recognized certifications ensures compliance with the most stringent regulatory and industry standards worldwide.

8. Conclusion

The Stainless Steel Coil Tube (Model 1437) from Wenzhou Jixing Metal Materials Co., Ltd represents a state-of-the-art solution for industrial heat exchange applications. By adhering to the principles established in standards such as GB/T 20950 for steel shell-and-tube spiral coil heat exchangers, this product delivers proven thermal performance, mechanical reliability, and corrosion resistance. The company's commitment to quality, continuous improvement, and customer-specific engineering solutions positions this product as a preferred choice for demanding industrial applications worldwide.