Stainless Steel Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube is a precision-engineered seamless or welded tubular product supplied in continuous coil form, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is designed for industrial applications requiring high corrosion resistance, mechanical integrity, and thermal stability. Unlike straight-length piping, the coil tube format offers superior material utilization, reduced cutting waste, and streamlined downstream processing through automated coil uncoiling and forming equipment. The coil configuration is particularly advantageous for high-volume manufacturing environments where continuous feed processing is essential.
The product is produced in accordance with international standards including ASTM A213 (Standard Specification for Seamless Ferritic Alloy Steel Tubing for Heat-Transfer and Similar Applications), ASTM A312 (Standard Specification for Seamless and Wrought Austenitic Stainless Steel Tubing), EN 10216-5, and JIS G3459. The coil tube is available in both austenitic and ferritic stainless steel grades, with dimensions tailored to customer specifications.
2. Material & Properties
The coil tube is manufactured from premium-grade stainless steel alloys, each selected to meet specific performance criteria. The primary material grades offered include:
- 304 / 304L (UNS S30400 / S30403) — General-purpose austenitic stainless steel with excellent corrosion resistance, formability, and weldability. The "L" designation denotes a low-carbon variant optimized for welding applications.
- 316 / 316L (UNS S31600 / S31603) — Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion in chloride-containing environments.
- 321 (UNS S32100) — Titanium-stabilized austenitic grade with enhanced resistance to intergranular corrosion at elevated temperatures.
- 310S (UNS S31008) — High-temperature austenitic grade with outstanding oxidation resistance up to 1150 °C.
- 430 / 439 (UNS S43000 / S43900) — Ferritic stainless steel grades offering good resistance to atmospheric and mild acid corrosion at a more economical cost.
2.1 Key Mechanical Properties
| Property | Grade 304/304L | Grade 316/316L | Grade 321 | Grade 310S | Grade 430 |
|---|---|---|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 515 | ≥ 515 | ≥ 515 | ≥ 410 |
| Yield Strength (MPa) | ≥ 205 | ≥ 205 | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 22 |
| Density (g/cm³) | 8.00 | 8.03 | 8.00 | 8.03 | 7.70 |
| Maximum Service Temperature (°C) | 870 | 870 | 925 | 1150 | 870 |
| Thermal Conductivity (W/m·K at 100 °C) | 16.3 | 16.3 | 15.1 | 14.2 | 26.2 |
2.2 Chemical Composition (Typical, wt%)
| Grade | C (max) | Mn (max) | P (max) | S (max) | Si (max) | Cr | Ni | Mo | Other |
|---|---|---|---|---|---|---|---|---|---|
| 304/304L | 0.08 / 0.03 | 2.00 | 0.045 | 0.030 | 1.00 | 18.0–20.0 | 8.0–10.5 | — | — |
| 316/316L | 0.08 / 0.03 | 2.00 | 0.045 | 0.030 | 1.00 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — |
| 321 | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 17.0–19.0 | 9.0–12.0 | — | Ti: 5×C–0.70 |
| 310S | 0.08 | 2.00 | 0.045 | 0.030 | 1.50 | 24.0–26.0 | 19.0–22.0 | — | — |
| 430 | 0.12 | 1.00 | 0.040 | 0.030 | 1.00 | 16.0–18.0 | — | — | — |
3. Specifications
The coil tube is manufactured to the following dimensional and performance specifications. Custom dimensions are available upon request with a minimum order quantity (MOQ) requirement.
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 219.0 mm |
| Wall Thickness | 0.5 mm – 12.0 mm |
| Coil Inner Diameter (ID) | 500 mm – 1,500 mm (standard); custom sizes available |
| Coil Weight | Up to 3,000 kg per coil (standard); up to 5,000 kg upon request |
| Coil Length (per coil) | 50 m – 500 m (variable, dependent on OD and wall thickness) |
| Manufacturing Method | Seamless (hot-rolled / cold-drawn) or ERW (Electric Resistance Welded) / TIG welded |
| Surface Finish | No. 1 (hot-rolled), 2B (cold-rolled and annealed), BA (Bright Annealed), No. 4 (brushed), Mirror (8K) |
| Tolerance — OD | ±0.05 mm (precision); ±0.1 mm (standard) |
| Tolerance — Wall Thickness | ±0.03 mm (precision); ±0.05 mm (standard) |
| Heat Treatment | Annealed (solution-annealed at 1050–1100 °C with water quench); pickled and passivated |
| End Condition | Plain end, beveled end, or threaded end (upon request) |
| Coil Forming | Individually formed and secured with steel strapping bands; wrapped in protective film and moisture-proof packaging |
| Standard Compliance | ASTM A213, ASTM A312, EN 10216-5, JIS G3459, GB/T 14976 |
4. Manufacturing Process
The production of stainless steel coil tube at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Procurement & Inspection — High-grade stainless steel billets or strip are sourced from certified mills. Incoming materials undergo 100% spectrographic analysis (OES — Optical Emission Spectroscopy) to verify chemical composition compliance.
- Hot Rolling or Cold Drawing — Billets are heated to forging temperature (1,100–1,250 °C) and pierced to form seamless hollow rounds, or cold-drawn from pre-formed billets through precision dies for tight-tolerance tubing.
- Intermediate Annealing & Pickling — The tube is annealed at 1,050–1,100 °C to relieve cold-work stresses and restore ductility, followed by acid pickling (HNO₃ + HF solution) to remove scale and impurities.
- Cold Sizing & Straightening — Precision cold-rolling or cold-drawing reduces the tube to final OD and wall thickness dimensions. The tube is straightened using multi-roll straightening equipment.
- Welding (for ERW/TIG variants) — For welded coil tube, edge-prepared strip is fed through induction heating coils (ERW) or TIG welding heads with argon gas shielding, followed by post-weld annealing.
- Final Annealing & Passivation — The tube undergoes final solution annealing, followed by chemical passivation treatment (HNO₃-based) to enhance the passive chromium oxide layer and improve corrosion resistance.
- Coil Forming & Packaging — The straightened and finished tube is fed through a precision coil forming machine. The coil is wound onto a steel core with controlled tension to prevent deformation. The completed coil is individually wrapped in PE protective film, secured with galvanized steel strapping bands, and palletized with moisture-absorbent desiccant for shipment.
- Quality Inspection & Testing — Every coil undergoes hydrostatic pressure testing (per ASTM A213), dimensional measurement, surface inspection, and mechanical testing (tensile, hardness, impact). Spectrographic re-verification of chemical composition is performed on a sampling basis.
5. Applications
The stainless steel coil tube is widely utilized across multiple industrial sectors due to its combination of corrosion resistance, mechanical strength, and processability:
- Heat Exchangers & Boilers — Used as tubes in shell-and-tube heat exchangers, condensers, evaporators, and steam generators in power generation, petrochemical, and HVAC (Heating, Ventilation, and Air Conditioning) systems.
- Food & Pharmaceutical Processing — Employed in sanitary-grade piping systems, mixing vessels, pasteurization equipment, and CIP (Clean-in-Place) systems due to compliance with FDA and 3-A sanitary standards.
- Chemical Processing — Used in reactor piping, distillation columns, and transfer lines handling aggressive chemicals, acids, and alkalis (particularly Grade 316L).
- Automotive Industry — Applied in exhaust system components, turbocharger piping, and fuel injection lines requiring high-temperature and corrosion resistance.
- Oil & Gas Industry — Used in wellhead equipment, subsea pipelines, and upstream/downstream processing facilities.
- Construction & Architecture — Employed in structural tubing, handrails, decorative elements, and building facade systems.
- Medical Devices — Used in surgical instrument handles, implant-grade tubing, and medical gas delivery systems.
- Downstream Coil Processing — The coil format enables seamless integration with automated tube-cutting, bending, forming, and machining lines, reducing material waste and labor costs.
6. Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework supported by the following certifications and compliance standards:
- ISO 9001:2015 — Quality Management Systems certification ensuring consistent product quality and customer satisfaction.
- ISO 14001:2015 — Environmental Management Systems certification demonstrating commitment to sustainable manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management Systems certification.
- EN 10204 Type 3.1 — Inspection Certificate providing detailed test results and traceability documentation for each batch of material.
- CE Marking — Compliance with European conformity requirements for products entering the European Economic Area.
- Mill Test Reports (MTR) — Full chemical composition and mechanical property reports provided with every shipment.
- Third-Party Inspection — Optional SGS, Bureau Veritas, or TÜV inspection services available for customer verification.
- Material Traceability — Each coil is assigned a unique heat number and batch code enabling full traceability from raw material to finished product.
7. Unique Selling Points
Superior Coil Forming Technology: The coil tube is produced using advanced precision coil forming equipment that ensures uniform coil geometry, minimal surface damage, and consistent winding tension — critical for downstream automated processing.