Stainless Steel Coil Tube (Coiltube) — Product No. 1284

1. Product Overview

The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") is a continuous-length tubular product manufactured in coil form, produced by Wenzhou Jixing Metal Materials Co., Ltd. This product category encompasses seamless and welded stainless steel tubes formed into coils, designed for downstream processing including cutting, bending, stamping, and further forming operations. The coil configuration provides logistical efficiency, reduced material waste, and enhanced production continuity for end-users in fabrication-intensive industries.

Coiltube products represent a critical segment of the tubular goods supply chain, bridging the gap between raw tube mills and precision fabrication facilities. The development of domestic coil tube production technology — including advances in continuous forming, multi-stand rolling, and in-line inspection — has significantly improved the dimensional accuracy, surface finish, and mechanical consistency of these products over the past two decades.

2. Material & Properties

2.1 Grade Classification

2.2 Typical Mechanical Properties (Annealed Condition)

Property SUS304 / 304L SUS316 / 316L SUS31803 (2205)
Tensile Strength (MPa) ≥ 520 ≥ 515 ≥ 450
Yield Strength (MPa) ≥ 205 ≥ 170 ≥ 450
Elongation (%) ≥ 40 ≥ 40 ≥ 25
Corrosion Resistance (EQU, pH 3.5, 35°C) Moderate Excellent Superior
Maximum Service Temperature (°C) 870 870 350 (limited)

2.3 Surface Finish Options

3. Specifications

Parameter Range / Options Standard Reference
Outer Diameter (OD) 3.0 mm – 168.3 mm ASTM A554 / EN 10216-5
Wall Thickness (WT) 0.3 mm – 6.0 mm ASTM A554 / ASME B36.19M
Coil Length (per roll) 1,000 m – 5,000 m (customizable) —
Coil Weight (per roll) 500 kg – 3,000 kg —
Inner Coil Diameter (ICD) 150 mm / 200 mm / 300 mm —
Outer Coil Diameter (OCD) 600 mm – 1,200 mm —
OD Tolerance ±0.1 mm (up to 25 mm OD); ±0.15% (above 25 mm OD) ASTM A554
WT Tolerance ±10% (minimum ±0.02 mm) ASTM A554
Manufacturing Process Seamless (Cold Drawn) / ERW (Electric Resistance Welded) / LSW (Laser Seam Welded) ASTM A213 / EN 10217-7
Heat Treatment Solution Annealed (1050–1150°C) + Water Quenched —
Applicable Standards ASTM, ASME, EN, DIN, JIS, GB/T —

4. Manufacturing Process

4.1 Seamless Coil Tube Production Route

  1. Raw Material Preparation: Hot-rolled stainless steel strip or bar stock undergoes incoming chemical composition verification (OES — Optical Emission Spectroscopy) and mechanical property testing.
  2. Hot Rolling / Extrusion: For larger OD products, steel billets are heated to 1,150–1,250°C and extruded or hot-rolled into hollow profiles.
  3. Piercing & Cross-Rolling: The hot blank is pierced to form a tube blank, then cross-rolled to achieve preliminary dimensions.
  4. Cold Drawing / Pilger Milling: The tube blank is cold-worked through a series of dies and plugs to achieve precise final OD and wall thickness dimensions. This cold working induces strain hardening and improves surface quality.
  5. Intermediate Annealing: Periodic annealing at 1,050–1,100°C relieves accumulated cold-work stresses and restores ductility for subsequent forming passes.
  6. Final Annealing & Pickling: Continuous annealing furnace treatment (atmosphere-controlled, dew point ≤ −50°C) followed by pickling to remove scale and form a passive chromium oxide layer.
  7. Coil Forming & Pay-Off: The finished tube is formed into coil configuration on a pay-off reel, with careful control of tension to prevent kinking, ovality, or edge damage.

4.2 Welded Coil Tube Production Route

  1. Strip Annealing: Cold-rolled stainless steel strip is annealed to ensure uniform mechanical properties for forming.
  2. Slitting & Edge Preparation: The strip is slit to target width with burr-free edges via precision slitting saws.
  3. Forming (Multi-Stand Rolling): The flat strip passes through a series of progressively reducing rolls to form a C-shape and then a closed tube. Modern multi-stand mills utilize servo-controlled roll gap for tight dimensional control.
  4. Welding: ERW (Electric Resistance Welding) or LSW (Laser Seam Welding) is applied to close the tube seam. Laser welding provides superior weld quality with minimal heat-affected zone (HAZ).
  5. Weld Repair & Inspection: Internal and external weld beads are trimmed and inspected via eddy current testing (ECT) or ultrasonic testing (UT).
  6. Sizing & Annealing: The tube passes through a sizing mill for final dimensional correction, followed by continuous annealing.
  7. Coil Coiling & Packaging: Finished product is coiled, wrapped in protective film, and palletized for shipment.

4.3 Key Process Innovations

Domestic production technology has advanced significantly in the following areas:

5. Applications

5.1 Industry Segments

Application Sector Typical Use Case Preferred Grade
Food & Beverage Processing Heat exchangers, piping systems, sanitary fittings SUS304 / 316L
Petrochemical & Oil/Gas Subsea pipelines, heat exchanger tubes, instrument tubing SUS316 / 31803
Pharmaceutical CIP/SIP piping, bioreactor components SUS316L (EP-grade)
Automotive Exhaust systems, fuel lines, sensor housings SUS409 / 321
Construction & Architecture Structural bracing, decorative elements, handrails SUS304 / 430
Medical Devices Endoscopes, surgical instruments, implant housings SUS316L
Energy & Power Generation Boiler tubes, solar thermal absorbers, nuclear components SUS310S / 321
Aerospace Fuel lines, hydraulic tubing, structural brackets SUS316 / Custom alloys

5.2 Advantages of Coil Configuration

6. Quality Certifications & Testing

6.1 Certifications

6.2 Inspection & Testing Protocol

  1. Chemical Analysis: OES (Optical Emission Spectroscopy) for each heat; PM (Pearlman Method) or LECO for carbon and sulfur verification.
  2. Mechanical Testing: Tensile testing (ASTM A370), hardness testing (HV30 per ASTM E92), and impact testing (Charpy V-notch per ASTM E23) as required.
  3. Non-Destructive Testing