Stainless Steel Coil Tube (Heat-Tracing Coil) — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube is a precision-engineered tubular product supplied in continuous coil form, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for heat-tracing (also referred to as "伴管" in Chinese engineering practice) and steam heating applications, with particular relevance to cement production and other industrial thermal transfer processes. The coil tube serves as a heat transfer medium, conveying steam, hot water, or thermal oil to maintain or elevate the temperature of process equipment, pipelines, and structural components.
Distinguished from standard straight-length tubes, the coil tube form factor offers significant advantages in terms of installation flexibility, material utilization efficiency, and reduced on-site welding requirements. The continuous coiled configuration allows for rapid deployment in complex geometries and large-scale industrial installations where linear tube segments would require extensive field joining and alignment.
2. Material & Properties
Coil tubes manufactured by Wenzhou Jixing Metal Materials Co., Ltd. are available in a range of austenitic and duplex stainless steel grades, selected to meet the demanding thermal, mechanical, and corrosion resistance requirements of industrial heat tracing applications.
2.1 Commonly Available Grades
- SUS304 / ASTM A269 Type 304 — General-purpose austenitic grade with excellent formability and corrosion resistance; suitable for moderate-temperature heat tracing up to approximately 870 °C.
- SUS316L / ASTM A269 Type 316L — Low-carbon variant with added molybdenum (2.0–3.0% Mo); superior resistance to pitting and crevice corrosion in chloride-containing environments.
- SUS321 / ASTM A269 Type 321 — Titanium-stabilized austenitic grade; resistant to sensitization and intergranular corrosion at elevated temperatures (up to 900 °C).
- SUS310S / ASTM A269 Type 310S — High-temperature austenitic grade with enhanced chromium (24–26% Cr) and nickel (19–22% Ni) content; suitable for sustained service temperatures up to 1150 °C.
- SUS347 / ASTM A269 Type 347 — Niobium-stabilized austenitic grade; comparable to Type 321 with improved resistance to intergranular corrosion.
2.2 Mechanical Properties (Typical for Type 304 Annealed Condition)
| Property | Specification | Test Standard |
|---|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa (75 ksi) | ASTM A269 / ASME SA-269 |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (30 ksi) | ASTM A269 / ASME SA-269 |
| Elongation (at Break) | ≥ 40% (in 50 mm gauge length) | ASTM A269 / ASME SA-269 |
| Hardness (Rockwell B) | ≤ 95 HRB | ASTM A269 |
| Density | 8.0 g/cm³ | — |
| Thermal Conductivity (at 100 °C) | 16.3 W/(m·K) | — |
| Thermal Expansion Coefficient (20–100 °C) | 17.3 × 10⁻⁶ /°C | — |
2.3 Chemical Composition (ASTM A269 Type 304 — Typical)
| Element | Carbon (C) | Chromium (Cr) | Nickel (Ni) | Manganese (Mn) | Silicon (Si) | Phosphorus (P) | Sulfur (S) |
|---|---|---|---|---|---|---|---|
| Max (%) | 0.08 | 18.0–20.0 | 8.0–10.5 | 2.0 | 1.0 | 0.045 | 0.030 |
3. Specifications
The following table summarizes the dimensional and performance specifications for the Stainless Steel Coil Tube product line:
| Parameter | Specification / Range | Reference Standard |
|---|---|---|
| Outer Diameter (OD) | Φ3.0 mm – Φ50.8 mm (1/8" – 2") | ASTM A269 / ASME SA-269 |
| Wall Thickness (WT) | 0.3 mm – 3.0 mm (0.012" – 0.118") | ASTM A269 / ASME SA-269 |
| OD Tolerance | ±0.05 mm (±0.002") | ASTM A269 |
| Wall Thickness Tolerance | ±10% of nominal | ASTM A269 |
| Coil Diameter | Φ300 mm – Φ1200 mm (adjustable per order) | — |
| Coil Weight | Up to 1,500 kg per coil | — |
| Surface Finish | Mill finish, pickled, or polished (Ra ≤ 0.4 μm on request) | ASTM A269 |
| End Condition | Plain ends, flared, threaded, or custom fittings | ASME B1.20.1 (for threaded) |
| Heat Treatment | Solution annealed (1050–1150 °C, water quench) | ASTM A269 |
| Maximum Service Temperature | Up to 1150 °C (grade-dependent) | — |
| Maximum Operating Pressure | Up to 100 bar (grade and dimension dependent) | ASME B31.3 / B31.5 |
| Material Standards | ASTM A269, ASME SA-269, EN 10217, GB/T 12771 | — |
| Product Standard | ASTM A269, ASME SA-269, EN 10217-7, GB/T 12771 | — |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous, multi-stage manufacturing process designed to ensure dimensional accuracy, metallurgical integrity, and consistent surface quality.
4.1 Process Flow
- Raw Material Procurement and Inspection — Hot-rolled stainless steel strip or coil is sourced from certified mills. Incoming material undergoes spectrographic analysis (PMI — Positive Material Identification) and mechanical property verification to confirm grade compliance and absence of contamination.
- Strip Cleaning and Surface Preparation — Raw strip is pickled (acid bath using HNO₃ + HF or H₂SO₄ + HNO₃ mixture) to remove scale, oxide, and surface contaminants. The strip is then descaled, rinsed, and dried to prepare for forming.
- Coil Forming (Roll Forming / Cold Forming) — The prepared strip is fed through a series of precision-rolled forming stations (roll stands) that progressively bend the flat strip into a tubular profile. The number of forming stations (typically 12–20) depends on the target diameter and wall thickness. This cold-forming process maintains the material's mechanical properties while achieving tight dimensional tolerances.
- Seam Welding (TIG / Laser Welding) — The formed tube is closed by Gas Tungsten Arc (GTAW/TIG) welding or laser welding along the longitudinal seam. The welding parameters (current, voltage, speed, shielding gas flow rate) are precisely controlled to produce a high-integrity weld. Back-purging with argon or nitrogen is employed to prevent internal oxidation of the weld root.
- Post-Weld Heat Treatment (Solution Annealing) — The welded coil tube is solution annealed at 1050–1150 °C followed by rapid water quenching. This process dissolves carbide precipitates formed during welding, restores full solution-strengthened microstructure, and ensures uniform corrosion resistance throughout the tube.
- Pickling and Passivation — Post-annealing pickling removes any residual oxide scale. A subsequent passivation treatment (using citric acid or nitric acid solutions) establishes a protective chromium oxide layer on the surface, enhancing long-term corrosion resistance.
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Dimensional Inspection and Quality Control — Each coil undergoes comprehensive inspection including:
- Visual inspection of weld seam quality and surface finish
- Dimensional verification (OD, WT, straightness) using automated gauging
- Hydrostatic or pneumatic pressure testing (typically at 1.5× maximum operating pressure)
- Eddy current testing (ECT) or ultrasonic testing (UT) of the weld seam for internal defects
- Chemical composition verification (OES — Optical Emission Spectroscopy)
- Coiling and Packaging — The inspected coil tube is wound onto a steel core, secured with strapping, and packaged with moisture barrier wrapping. Each coil is labeled with a unique heat number, material grade, dimensions, and certification documentation.
5. Applications
The Stainless Steel Coil Tube is engineered for a broad spectrum of industrial applications, with particular emphasis on thermal management and heat tracing systems:
5.1 Primary Applications
- Cement Industry — Heat Tracing and Steam Heating — As highlighted in the product's technical literature ("伴管蒸汽加热传热水泥研制"), coil tubes are employed as heat tracing lines (伴管) alongside cement kiln feed pipes, rotary kilns, preheater towers, and clinker coolers. Steam or hot oil is circulated through the coil tubes to prevent material freezing, maintain optimal process temperatures, and ensure consistent cement quality.
- Oil and Gas Industry — Heat tracing of pipelines, storage tanks, and process equipment to prevent hydrocarbon solidification and maintain flow assurance in cold environments.
- Chemical Processing — Heating and temperature control of reactors, heat exchangers, distillation columns, and process piping where corrosion resistance is critical.
- Food and Beverage Industry — Sanitary-grade coil tubes (polished finish, Ra ≤ 0.4 μm) for CIP (Clean-in-Place) systems, steam sterilization lines, and heating coils in processing equipment.
- Pharmaceutical Manufacturing — Precision coil tubes for controlled heating in bioreactors, fermentation vessels, and sterile processing lines.
- Power Generation — Steam tracing and heating applications in power plant auxiliary systems, including feedwater preheating and boiler tube protection.
- Marine and Offshore — Heat tracing for shipboard piping systems, offshore platform process lines, and ballast tank heating.
- Automotive and Aerospace — Precision coil tubes for fuel lines, hydraulic systems, and thermal management components requiring tight dimensional tolerances.
5.2 Unique Selling Points
1. Continuous Coil Configuration — Eliminates the need for field welding and alignment of individual tube segments, reducing installation time by up to 60% and minimizing leak points in critical heat tracing applications.
2. Superior Thermal Performance — The coil geometry maximizes surface area per unit length, enhancing heat transfer efficiency in steam and hot water heating systems. Combined with the high thermal conductivity of austenitic stainless steel, this ensures rapid and uniform temperature distribution.
3. Proven Cement Industry Application — Backed by dedicated R&D literature on "steam heating heat tracing for cement production," the product has been validated for the extreme thermal cycling and abrasive conditions of cement manufacturing environments.
4. Full Traceability — Each coil is supplied with a complete material test certificate (MTC) traceable to the original mill heat number, ensuring full supply chain transparency and compliance with international quality standards.
5. Customization Capability —