Stainless Steel Coil Tube (Coil Tubing) — Product Technical Specification

1. Product Overview

Stainless steel coil tubes, also known as coiled tubing or continuous coil tube, are precision-engineered seamless or welded stainless steel tubes formed into continuous coils for convenient storage, transportation, and on-site deployment. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., these coil tubes are designed to meet the rigorous demands of industrial, energy, medical, and process engineering applications.

Coil tube design requires careful consideration of several critical engineering parameters, including coil diameter selection, tube curvature radius, stress distribution during forming, and the residual stresses that affect long-term mechanical performance. The design of coil tubes must balance the geometric constraints of coiling with the material's mechanical integrity to ensure reliable performance in service conditions.

2. Material & Properties

Stainless steel coil tubes are available in a wide range of austenitic, ferritic, and duplex stainless steel grades, each selected to suit specific application requirements:

• Austenitic Grades: AISI 304, 304L, 316, 316L, 321, 347 — offering excellent corrosion resistance, weldability, and formability.
• Ferritic Grades: AISI 409, 430, 439 — providing good resistance to stress corrosion cracking and moderate forming capability.
• Duplex Grades: UNS S31803 (2205), UNS S32750 (2507) — delivering superior yield strength and resistance to chloride-induced pitting and crevice corrosion.
• Super-Austenitic Grades: Alloy 20, C-276 — for highly aggressive chemical environments.

Key mechanical and physical properties of the coil tube material include:

• Yield strength (Rp0.2) ranging from 205 MPa (304) to over 550 MPa (2507 duplex)
• Tensile strength (Rm) ranging from 515 MPa to 795 MPa depending on grade
• Elongation (A50) typically between 40% and 60% for annealed austenitic grades
• Corrosion resistance characterized by PREN (Pitting Resistance Equivalent Number) values from 18 (304) to 42+ (2507)
• Operating temperature range from cryogenic (-196°C) to 870°C depending on grade

3. Specifications

Parameter	Specification
Product Name	Stainless Steel Coil Tube (Coiltube)
Product Code	1126
Manufacturing Method	Hot Rolled & Cold Drawn / Seamless & Welded
Outer Diameter (OD)	3.0 mm – 108.0 mm
Wall Thickness	0.3 mm – 6.0 mm
Coil Diameter	500 mm – 1,200 mm
Coil Length	100 m – 3,000 m (continuous)
Surface Finish	2B, No. 1, BA (Bright Annealed), Polished (Ra 0.4–1.6 μm)
Applicable Grades	304, 304L, 316, 316L, 321, 347, 430, 2205, 2507, Alloy 20
Applicable Standards	ASTM A213/A269, ASME B36.19M, EN 10216-5, GB/T 12771, JIS G3459
Tolerance (OD)	±0.05 mm – ±0.20 mm (per customer specification)
Tolerance (Wall Thickness)	±0.03 mm – ±0.10 mm
End Form	Plain end, Beveled end, Threaded end, Flanged end
Packaging	Coil wrapped in moisture-proof film, wooden crate or steel frame

4. Manufacturing Process

The production of high-quality stainless steel coil tubes involves a multi-stage manufacturing process with strict quality control at each step:

1. Raw Material Selection: High-purity stainless steel billets or strip are procured from certified mills, with chemical composition verified via spectroscopic analysis (OES) to ensure conformity with the specified grade.
2. Piercing & Hot Rolling: Billets are heated to controlled temperatures and pierced to produce seamless tube blanks, or continuous strip is formed and welded (ERW/ODW) for welded coil tubes.
3. Hot Finishing: Tubes undergo hot finishing to achieve approximate final dimensions, followed by pickling and descaling to remove surface oxide scale.
4. Cold Drawing / Cold Rolling: Tubes are cold-worked through precision dies or rolling mills to achieve final dimensional tolerances, improved surface finish, and enhanced mechanical properties. This step is critical for coil tube design as it introduces controlled work hardening.
5. Coiling / Forming: The straight tubes are carefully formed into coils using specialized coiling equipment. The coil diameter must be selected to avoid excessive bending stress that could compromise the tube's structural integrity. A minimum bending radius of 3–5 times the outer diameter is typically maintained.
6. Solution Annealing: Where required, tubes are solution-annealed (1050°C – 1150°C) and water-quenched to relieve residual stresses introduced during cold working and coiling, restoring full corrosion resistance and ductility.
7. Precision Cutting: Coils are cut to specified lengths using abrasive or plasma cutting systems, with end finishing to remove burrs and heat-affected zones.
8. Surface Treatment: Optional surface treatments include electropolishing, passivation, or mechanical polishing to achieve specified surface roughness values.
9. Quality Inspection & Testing: Final products undergo comprehensive inspection including dimensional measurement, hydrostatic testing, ultrasonic flaw detection (UT), and surface inspection.

5. Applications

Stainless steel coil tubes find extensive application across numerous industries due to their combination of corrosion resistance, mechanical strength, and the convenience of continuous coil form:

• Oil & Gas Industry: Coiled tubing (CT) systems for well intervention, perforation, logging, and stimulation operations. Continuous coil tubes enable rapid deployment without threading connections, reducing operational downtime.
• Chemical Processing: Heat exchanger tubes, reactor internals, and process piping systems handling corrosive chemicals including acids, alkalis, and halide-containing solutions.
• Food & Beverage Industry: Hygienic-grade piping (Ra ≤ 0.5 μm) for dairy, brewing, pharmaceutical, and beverage processing where sanitary requirements are paramount.
• Medical & Pharmaceutical: Medical gas delivery systems, autoclave components, and pharmaceutical process equipment requiring biocompatible, corrosion-resistant tubing.
• Power Generation: Boiler tubes, superheater tubes, and condensate lines in thermal and nuclear power plants.
• Automotive & Aerospace: Fuel system lines, exhaust components, and hydraulic lines requiring high-temperature resistance and fatigue performance.
• Marine & Offshore: Seawater cooling systems, desalination plant components, and offshore platform piping systems.
• Construction & Architecture: Structural tubing for modern architectural applications, handrails, and facade systems.

6. Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and adheres to international standards to ensure product reliability and traceability:

• ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and customer satisfaction.
• ISO 14001:2015 — Environmental Management System certification for environmentally responsible manufacturing practices.
• ISO 45001:2018 — Occupational Health and Safety Management System.
• EN 10204 3.1 — Material Test Certificate (MTC) provided for every production batch, confirming chemical composition, mechanical properties, and dimensional compliance.
• ASME — American Society of Mechanical Engineers certification for pressure vessel and piping applications.
• NACE MR0175 / ISO 15156 — Compliance for sour service applications (H₂S-containing environments).
• API — American Petroleum Institute standards for oil and gas industry applications.
• 3-A Sanitary Standards — For food-grade and pharmaceutical applications requiring hygienic surface finish.

Every coil tube batch undergoes the following quality assurance procedures:

• 100% visual and dimensional inspection
• Hydrostatic pressure testing (1.5× working pressure, held for specified duration)
• Ultrasonic testing (UT) for internal defects
• Magnetic particle inspection (MT) or penetrant testing (PT) for surface defects
• Spectroscopic chemical analysis (OES) for composition verification
• Mechanical property testing (tensile, hardness, impact) per applicable standards
• Corrosion testing (pitting, intergranular, stress corrosion cracking) as required

7. Unique Selling Points

Stainless steel coil tubes from Wenzhou Jixing Metal Materials Co., Ltd. offer distinct advantages over conventional straight-length tubing:

• Continuous Length Supply: Coils of up to 3,000 meters eliminate the need for field welding and threading, reducing installation time by up to 40% and minimizing leak points in critical systems.
• Optimized Material Utilization: Continuous coil production reduces waste by up to 95% compared to cut-length tube manufacturing, offering both cost and environmental advantages.
• Design Flexibility: Coiled tubes can be deployed in complex geometries without the need for additional fittings, making them ideal for coiled tubing (CT) operations in oil and gas well intervention.
• Enhanced Surface Quality: Cold-drawn coil tubes achieve superior surface finish (Ra 0.4–1.6 μm) critical for hygienic and corrosive service applications.
• Full Traceability: Every coil is provided with complete material traceability documentation, enabling compliance with regulatory requirements in regulated industries.
• Customization Capability: Flexible manufacturing capability allows customization of coil diameter, tube dimensions, surface finish, and end preparation to meet specific project requirements.
• Engineered for Coil Design Integrity: Advanced forming technology ensures that residual stresses introduced during coiling are minimized through controlled annealing, preserving the tube's full mechanical and corrosion performance throughout its service life.

8. Technical Note: Coil Tube Design Considerations

Based on engineering experience and technical literature review, the following design considerations are critical for stainless steel coil tube applications:

• Minimum Bend Radius: The coil diameter must be sufficient to prevent plastic deformation or cracking. A minimum coil diameter of 3–5 times the tube outer diameter is recommended for austenitic grades, and 5–8 times for duplex grades.
• Residual Stress Management: Coiling introduces residual stresses that may affect fatigue life and corrosion resistance. Solution annealing after coiling is recommended for critical applications.
• Uncoiling Force Calculation: The force required to uncoil the tube must be calculated based on tube diameter, wall thickness, material yield strength, and coil diameter to select appropriate uncoiling equipment.
• Creep and Relaxation: Long-term storage in coil form may cause dimensional relaxation, particularly at elevated temperatures. Storage conditions should be controlled to maintain dimensional stability.
• Welding Considerations: If field welding is required, the heat-affected zone (HAZ) must be evaluated for potential sensitization, particularly for carbon-containing austenitic grades.

For detailed technical consultation, material selection guidance, or custom coil tube specifications, please contact Wenzhou Jixing Metal Materials Co., Ltd. engineering team.