Stainless Steel Coil Tube (盘管 Coiltube) — Technical Specification

Product Code: 1629  |  Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. (温州继兴金属材料有限公司)  |  Classification: Literature Learning / Technical Reference

1. Product Overview

The Stainless Steel Coil Tube (盘管 Coiltube) is a precision-engineered tubular component manufactured in a continuous helical coil configuration. Unlike conventional straight-length stainless steel tubing, the coil tube is produced in a wound spiral form, offering distinct advantages in terms of material utilization, storage efficiency, and downstream processing flexibility. This product category is particularly significant in applications involving radiant heating systems, heat exchangers, and localized thermal management solutions.

The technical reference material associated with this product — "Coil Tube — Steel Plate Radiant Panel Local Heating Test Summary" (盘管—钢板式辐射板局部采暖的试验小结) — documents experimental investigations into the thermal performance characteristics of coil tubes integrated with steel plate radiant panels for localized space heating. These studies provide empirical data on heat transfer efficiency, thermal distribution uniformity, and system reliability under various operating conditions.

Coil tubes are manufactured primarily from austenitic stainless steel grades, leveraging the inherent corrosion resistance, mechanical strength, and thermal conductivity properties of these alloys. The continuous coil form factor eliminates the need for post-manufacturing cutting and joining operations, reducing both material waste and potential failure points at weld seams.

2. Material & Properties

2.1 Base Material Grades

The coil tube product line encompasses multiple stainless steel grades, selected based on the specific application requirements:

2.2 Key Physical Properties

2.3 Corrosion Resistance

Austenitic stainless steel coil tubes exhibit robust resistance to atmospheric corrosion, weak acids, and alkaline solutions. The passivation layer formed by the chromium oxide film provides self-healing protection against oxidation. Grade 316 coil tubes additionally demonstrate superior resistance to pitting and crevice corrosion in chloride-containing environments, with a critical pitting temperature (CPT) exceeding 30°C in 3.5% NaCl solution.

3. Technical Specifications

Parameter Specification Standard Reference
Outer Diameter (OD) 6.0 mm – 50.8 mm (¼" – 2") ASTM A213 / GB/T 12771
Wall Thickness 0.5 mm – 3.0 mm ASTM A213 / GB/T 12771
Coil Inner Diameter (CID) 150 mm – 600 mm (customizable) Manufacturer Specification
Coil Length per Spool 10 m – 500 m (continuous) Manufacturer Specification
Dimensional Tolerance (OD) ±0.05 mm (precision); ±0.10 mm (standard) ASTM A213 / EN 10216
Dimensional Tolerance (Wall) ±10% (standard); ±5% (precision) ASTM A213 / EN 10216
Roundness ≤ 1.0% of nominal OD ASTM A213
Surface Roughness (Ra) 0.4 – 1.6 μm (2B finish); ≤ 0.2 μm (BA finish) ASTM A473
End Condition Plain, beveled, or formed (per customer requirement) Custom
Helix Angle Deviation ≤ ±1.5° Internal Quality Standard
Residual Stress Stress-relieved per ASTM A213 ASTM A213
Testing Standards Hydrostatic test, Eddy current testing (ECT), Spectroscopic analysis ASTM A269 / GB/T 24511

4. Manufacturing Process

4.1 Process Flow

  1. Strip Sourcing & Incoming Inspection: Cold-rolled stainless steel strip (CRSS) conforming to ASTM A478/A478M is procured and subjected to spectroscopic verification (PMI — Positive Material Identification), dimensional measurement, and visual surface inspection.
  2. Edge Preparation: Strip edges are trimmed and deburred to eliminate burrs and edge defects that could propagate into the final coil tube wall.
  3. Tube Forming (Cold Forming): The strip is fed through a series of progressively closing rolls (forming mill) that gradually deform the flat strip into a tubular cross-section. This multi-roll forming process ensures uniform wall thickness and precise dimensional control without the need for welding.
  4. Seam Welding (if applicable): For welded coil tubes, a high-frequency resistance seam welding (HFRSW) or laser welding process is applied at the roll closure point. Weld parameters are continuously monitored and recorded for traceability.
  5. Coil Winding: The formed tube is wound onto a precision-controlled coil former at a constant helix pitch, maintaining uniform curvature and preventing mechanical deformation or kinking. Tension control systems ensure consistent coil density.
  6. Stress Relief Annealing: The coiled tube undergoes a controlled annealing cycle (typically 1050–1100°C for austenitic grades, followed by controlled cooling) to relieve residual cold-work stresses, restore full ductility, and stabilize the microstructure.
  7. Pickling & Passivation: The annealed coil tube is subjected to acid pickling (hydrochloric/nitric acid blend) to remove oxide scale, followed by passivation treatment to establish the protective chromium oxide film.
  8. Final Inspection & Testing: Each coil undergoes hydrostatic pressure testing (typically 1.5× working pressure), eddy current flaw detection for wall integrity, and dimensional verification. Surface finish is assessed against ASTM A473 standards.
  9. Packaging & Dispatch: Coils are wrapped in protective film, secured on steel reels, and packed in export-grade wooden crates or steel containers for shipment.

4.2 Process Advantages

The continuous coil forming process offers significant material efficiency advantages over discrete straight-length tube production. Material yield exceeds 95%, compared to approximately 85% for cut-and-weld production methods. The elimination of longitudinal weld seams (in seamless coil tubes) or the use of precision high-frequency welds ensures superior pressure containment integrity.

5. Applications

5.1 Radiant Heating Systems (Primary Application)

Based on the referenced experimental study "Coil Tube — Steel Plate Radiant Panel Local Heating Test Summary," stainless steel coil tubes are extensively employed in steel plate radiant heating panels for localized space heating. The coil configuration provides:

5.2 Additional Application Domains

6. Quality Certifications & Standards Compliance

6.1 Product Standards

6.2 Quality Management & Certifications

6.3 Testing & Inspection Protocols

7. Unique Selling Points

The Wenzhou Jixing Metal Materials Co., Ltd. Stainless Steel Coil Tube product line distinguishes itself through the following competitive advantages: