Stainless Steel Coil Tube (Coil Pipe) — Product No. 1708

1. Product Overview

The Stainless Steel Coil Tube (also referred to as Coil Pipe or Continuous Coil Tube) is a precision-engineered tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is supplied in a coiled configuration, enabling seamless integration into automated forming, cutting, and fabrication lines. Unlike seamless or welded straight pipes, coil tubes offer superior flexibility in downstream processing, reduced material waste, and enhanced productivity for high-volume manufacturing environments.

The product is designed for applications requiring excellent corrosion resistance, mechanical integrity, and dimensional accuracy — including HVAC systems, refrigeration circuits, heat exchangers, chemical processing, and automotive components. The coil format eliminates the need for butt welding of individual straight lengths, thereby minimizing potential failure points and improving overall system reliability.

2. Material & Properties

2.1 Alloy Composition

The coil tube is fabricated from austenitic stainless steel grades conforming to international standards. The primary grade utilized is AISI 304 (UNS S30400 / 1.4301), with optional availability in AISI 316L (UNS S31603 / 1.4404) for enhanced resistance to chlorides and aggressive chemical environments.

Chemical Element AISI 304 (wt%) AISI 316L (wt%)
Carbon (C) ≤ 0.08 ≤ 0.03
Manganese (Mn) ≤ 2.00 ≤ 2.00
Phosphorus (P) ≤ 0.045 ≤ 0.045
Sulfur (S) ≤ 0.030 ≤ 0.030
Chromium (Cr) 18.00 – 20.00 16.00 – 18.00
Nickel (Ni) 8.00 – 10.50 10.00 – 14.00
Molybdenum (Mo) — 2.00 – 3.00
Iron (Fe) Balance Balance

2.2 Mechanical Properties

Property Specification
Tensile Strength (UTS) ≥ 520 MPa (75,400 psi)
Yield Strength (0.2% Offset) ≥ 205 MPa (29,700 psi)
Elongation at Break ≥ 40%
Hardness (Brinell) ≤ 217 HB
Operating Temperature Range −196 °C to +870 °C (−320 °F to +1,600 °F)
Density 8.0 g/cm³
Thermal Conductivity (20 °C) 16.3 W/(m·K)

2.3 Corrosion Resistance

3. Specifications

Parameter Specification
Product Code 1708
Product Type Stainless Steel Coil Tube (Continuous Coil Pipe)
Outer Diameter (OD) 3.0 mm – 50.8 mm (1/8" – 2")
Wall Thickness 0.30 mm – 3.00 mm
OD Tolerance ± 0.05 mm (standard); ± 0.02 mm (precision grade)
Wall Thickness Tolerance ± 10% of nominal
Coil Length 50 m – 500 m per coil (customizable)
Coil Weight 50 kg – 500 kg (standard); up to 1,000 kg upon request
Surface Finish 2B Annealed, No. 1 Hot Rolled, BA (Bright Annealed), Electropolished, Brushed
Heat Treatment Condition Fully Annealed and Pickled (Solution Annealed)
End Treatment Plain cut, beveled, or threaded (upon request)
Packaging Export-grade wooden pallet with moisture-proof wrapping
Standards Compliance ASTM A269, ASTM A213, EN 10216-5, GB/T 12771

4. Manufacturing Process

4.1 Production Flow

  1. Raw Material Procurement: Cold-rolled stainless steel strip (CRSS) sourced from certified mills (e.g., Outokumpu, POSCO, Baosteel), verified for chemical composition and mechanical properties.
  2. Strip Inspection: Incoming strip undergoes 100% ultrasonic testing for subsurface defects, visual inspection for surface imperfections, and spectrometric analysis for alloy verification.
  3. Slitting: Precision slitting to required strip width with edge trimming to ensure uniform coil tube wall thickness.
  4. Forming (ERW / Laser Welding): The strip is formed into a tubular shape via Electric Resistance Welding (ERW) or laser welding technology. For seamless variants, the tube is produced via hot or cold piercing followed by cold drawing.
  5. Weld Heat-Affected Zone (HAZ) Treatment: Internal and external grinding of the weld seam to achieve uniform wall thickness and surface smoothness.
  6. Solution Annealing: Continuous annealing in a controlled atmosphere (hydrogen or vacuum) at 1050–1150 °C to dissolve carbides and restore full austenitic microstructure.
  7. Pickling and Passivation: Immersion in dilute nitric/hydrofluoric acid solution to remove scale and form a protective chromium oxide passive layer.
  8. Coiling: The finished tube is wound onto precision spools at controlled tension to prevent deformation or kinking.
  9. Final Quality Control: Dimensional verification, hydrostatic testing (typically at 2.0–3.0 × working pressure), and surface finish assessment.

4.2 Key Process Parameters

Process Stage Key Parameter Control Range
Forming Rolling Speed 10 – 60 m/min
ERW Welding Welding Current 8 – 25 kA
ERW Welding Welding Voltage 4 – 8 V
Annealing Temperature 1050 – 1150 °C
Annealing Dwell Time 15 – 45 min
Hydrostatic Test Test Pressure 2.0 × Maximum Working Pressure
Hydrostatic Test Hold Time ≥ 5 seconds

5. Applications

5.1 HVAC and Refrigeration Systems

Coil tubes are extensively employed in the manufacturing of fan coil units, air handling units (AHUs), condenser and evaporator coils, and refrigeration circuit tubing. The continuous coil format enables automated bending and brazing operations, significantly reducing labor costs and production cycle times compared to straight pipe segments.

5.2 Heat Exchangers

Used in shell-and-tube heat exchangers, plate-fin heat exchangers, and radiators for automotive and industrial applications. The superior thermal conductivity and corrosion resistance of austenitic stainless steel ensure long service life under thermal cycling conditions.

5.3 Chemical and Pharmaceutical Processing

AISI 316L coil tubes are specified for fluid conveyance in chemical reactors, distillation columns, and pharmaceutical clean-in-place (CIP) systems where resistance to aggressive media and hygiene-grade surface finishes are critical.

5.4 Food and Beverage Industry

Compliant with FDA 21 CFR and EU 1935/2004 regulations, these coil tubes are used in dairy processing lines, beer brewing systems, and potable water distribution networks.

5.5 Automotive and Aerospace

Applied in fuel lines, exhaust system components, turbocharger manifolds, and hydraulic systems where high-temperature resistance and fatigue durability are paramount.

6. Quality Certifications

6.1 Product Certifications

6.2 Testing and Inspection Protocols

Test Method Standard Frequency
Chemical Composition Analysis OES / Spark Spectrometry Per heat lot
Hydrostatic Pressure Test ASTM A269 / EN 10216-5 100% of coils
Ultrasonic Flaw Detection ASTM E213 100% of coils
Tensile Test ASTM A370 Per heat lot
Intergranular Corrosion Test ASTM A262 Practice 1A (EPR Test) Per heat lot (annual)
Dimensional Verification Caliper / Micrometer / Profile Projector Per coil
Surface Roughness Measurement ASTM B608 / Ra ≤ 0.8 μm Per coil

7. Unique Selling Points

Why Choose Wenzhou Jixing Metal Materials Co., Ltd. Coil Tubes?

  1. Continuous Coil Format Advantage: Eliminates butt welds and joint failures; enables automated downstream processing, reducing labor by up to 60% and improving throughput significantly.
  2. Precision Dimensional Control: Tolerances as tight as ±0.02 mm on OD and ±10% on wall thickness ensure interchangeability and reliable fit in automated assembly lines.
  3. Multi-Grade Availability: Single-source supply of 304, 316L, 321, 310S, and duplex (2205) grades simplifies procurement and reduces supply chain complexity.
  4. Custom Surface Finishes: From industrial 2B to electropolished Ra ≤ 0.4 μm finishes for pharmaceutical and food-grade applications, tailored to specific end-use requirements.
  5. Comprehensive Traceability: Each coil is laser-marked with heat number, grade, dimensions, and production date, enabling full traceability from mill to end application.
  6. Integrated Value-Added Services: In-house capabilities for custom cutting, bending, threading, end-finishing, and packaging reduce total project cost and lead time.
  7. Competitive Lead Time: Standard coils available within 7–15 days; custom specifications delivered within 20–30 days, supported by strategic inventory of raw strip material.

8. Storage and Handling Recommendations