Stainless Steel Spiral Coiltube — Hot Push Forming Process

Product Code: JX-ST-1555  |  Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.  |  Classification: Process Engineering & Forming Technology

1. Product Overview

The Stainless Steel Spiral Coiltube (Coiltube) is a precision-engineered tubular product manufactured through the Hot Push Spiral Forming Process — an advanced manufacturing methodology that combines controlled thermal expansion with helical winding to produce seamless spiral coils and associated elbow fittings. Unlike conventional cold-drawn or rolled coil tubes, the hot push forming method enables the production of large-diameter, thick-walled spiral tubes with superior dimensional accuracy and uniform microstructure.

This product category encompasses both the continuous spiral coil tubes and the integral elbow fittings formed using the same hot push forming equipment and methodology. The technology is particularly suited for applications requiring high-temperature resistance, corrosion resistance, and mechanical integrity in continuous coil configurations.

2. Material & Properties

2.1 Applicable Grades

2.2 Mechanical Properties (Typical — SUS316L Reference)

Property Unit Typical Value Test Standard
Tensile Strength (Rm) MPa ≥ 485 ASTM A270 / EN 10216-5
Yield Strength (Rp0.2) MPa ≥ 205 ASTM A270 / EN 10216-5
Elongation (A50) % ≥ 40 ASTM A270 / EN 10216-5
Hardness (HV30) HB ≤ 220 ASTM A270
Maximum Service Temperature °C ≤ 870 Material-specific
Cold Bending Capability — ≥ 5D without cracking EN 10216-5

2.3 Chemical Composition (SUS316L — Typical)

C Si Mn P S Cr Ni Mo N
≤ 0.030 ≤ 1.00 ≤ 2.00 ≤ 0.045 ≤ 0.030 16.5–18.5 10.0–14.0 2.00–2.50 ≤ 0.10

3. Specifications

Parameter Range / Specification Notes
Outer Diameter (OD) Φ6.0 mm – Φ219.1 mm (1/4" – 8") Custom sizes available upon request
Wall Thickness (WT) 0.3 mm – 6.0 mm Standard: 0.5 / 0.8 / 1.0 / 1.2 / 1.5 / 2.0 mm
Spiral Pitch 30 mm – 300 mm Determined by application geometry requirements
Coil Length per Spool 5 m – 200 m (continuous) Unlimited continuous production capability
Helix Diameter (H) Φ50 mm – Φ2,000 mm Custom helical winding configurations
Surface Finish 2B, No.1, BA, HL, Mirror (Ra ≤ 0.1 μm) Electropolished finish available
Dimensional Tolerance (OD) ±0.05 mm (precision grade) Standard grade: ±0.10 mm
Dimensional Tolerance (WT) ±10% of nominal Per ASTM A270
End Condition Plain, Beveled, Threaded, Flanged Custom end preparation available
Elbow Angle (Integral) 15°, 30°, 45°, 60°, 90°, 180° Formed in-line during hot push process
Standard Reference ASTM A269, A270, A312; EN 10216-5; GB/T 12771 Multi-standard compliance

4. Manufacturing Process

4.1 Process Flow Diagram

  1. Raw Material Inspection & Receiving: Stainless steel strip or tube blank received from certified mills; incoming inspection per ASTM A270 for chemical composition (OES analysis), mechanical properties, and surface quality.
  2. Pre-Forming Preparation: Dimensional verification, surface cleaning, and marking of coil blank for traceability.
  3. Hot Push Forming (Core Process): The tube blank is heated to a controlled temperature range (typically 850–1,050°C for austenitic grades) using induction heating or controlled furnace heating. The heated tube is then pushed through precision spiral forming dies using hydraulic or mechanical push systems. The combination of elevated temperature and controlled die geometry produces the helical spiral configuration with minimal residual stress.
  4. Elbow Integration (if applicable): Integral elbow fittings are formed during the same hot push operation by redirecting the tube through angled die stations. This eliminates the need for separate welding of elbow components, producing a fully seamless configuration.
  5. Controlled Cooling & Stress Relief: Post-forming controlled cooling (air cooling or furnace cooling depending on grade) followed by solution annealing at 1,010–1,150°C with water quench to restore full austenitic microstructure and eliminate forming stresses.
  6. Surface Finishing: Pickling and passivation treatment (HNO₃/HF acid bath) to remove scale and restore chromium oxide passive layer. Optional mechanical polishing or electropolishing for high-surface-quality applications.
  7. Dimensional Inspection: Full-length dimensional verification using laser measurement systems, ultrasonic wall thickness gauging, and helix geometry verification (pitch, helix diameter, roundness).
  8. Non-Destructive Testing (NDT): 100% eddy current testing (ECT) for surface and near-surface defects; ultrasonic testing (UT) for internal wall integrity; visual inspection per ASTM E165.
  9. Packaging & Dispatch: Protected packaging with moisture barrier, coil secured on custom spools, accompanied by mill test certificates (MTC) and traceability documentation.

4.2 Hot Push Forming — Technical Advantages Over Conventional Methods

5. Applications

5.1 Primary Industries

5.2 Typical Operating Conditions

Application Sector Temperature Range Pressure Range Corrosive Media
Petrochemical Processing -40°C to 600°C 0.1 – 15 MPa H₂S, CH₄, aromatics
Pharmaceutical 20°C to 150°C 0.1 – 1.0 MPa Steam, sanitizing agents
Marine/Desalination 10°C to 90°C 0.1 – 4.0 MPa Seawater, chlorides
Power Generation 200°C to 650°C 1.0 – 15.0 MPa Water/steam

6. Quality Certifications & Compliance

6.1 Quality Management System Certifications

6.2 Product & Process Certifications