Large-Diameter Stainless Steel Coil Tube (Φ25mm – Φ50mm+) for Industrial Pipelines and Heat Exchangers

Product Overview

Wenzhou Jixing Metal Materials Co., Ltd. presents its premium Large-Diameter Stainless Steel Coil Tube, engineered specifically for demanding applications requiring outer diameters ranging from Φ25 mm (0.98 in) to Φ50 mm and above (2.0 in+). This product category, designated as Series No. 34 within the company's comprehensive product specification system, represents the upper tier of the company's coil tube diameter range. Designed for main pipeline systems, long-distance fluid transport, and large-scale heat exchanger coil assemblies, these tubes deliver exceptional mechanical integrity, corrosion resistance, and thermal performance in continuous coiled form.

The large-diameter coil tube line is manufactured to the highest industry standards, combining advanced cold-drawing and cold-rolling technologies with rigorous quality control at every stage. Available in seamless and welded configurations, these tubes accommodate a wide variety of stainless steel grades including 304, 304L, 316, 316L, 321, 310S, and duplex grades such as 2205, ensuring compatibility with virtually any process environment.

Material & Properties

The large-diameter coil tubes are fabricated from high-purity austenitic and duplex stainless steel grades, each selected to optimize performance for specific operating conditions:

All grades are supplied with full mill test certificates confirming chemical composition and mechanical properties in compliance with ASTM, EN, and ISO standards.

Specifications

Parameter Specification
Product Category Coil Tube – Large Diameter Series (Series No. 34)
Outer Diameter Range Φ25 mm – Φ50 mm+ (0.98 in – 2.0 in+)
Wall Thickness Range 0.5 mm – 6.0 mm (0.020 in – 0.236 in)
Coil ID (Inner Diameter of Coil) Φ50 mm – Φ300 mm (2.0 in – 11.8 in)
Coil Length per Roll Up to 1,500 m (4,921 ft) or custom per customer requirement
Manufacturing Method Seamless / Welded (BUTT, ERW, TIG)
Surface Finish 2B, BA (Bright Annealed), Pickled, Hairline, No. 4, Mirror
Applicable Grades 304, 304L, 316, 316L, 321, 310S, 2205, 310, 904L, Custom Alloys
Standards ASTM A213 / A269 / A778, EN 10216-5, ISO 4200, GB/T 12771
Operating Temperature Range −196 °C to +1150 °C (−321 °F to +2094 °F) depending on grade
Maximum Working Pressure Up to 40 MPa (5,800 psi) depending on wall thickness and grade
Delivery Condition Annealed, Solution Treated, Cold Worked

Manufacturing Process

1. Raw Material Selection and Inspection

High-grade stainless steel billets or wire rods are sourced from certified mills and subjected to ultrasonic testing, spectral analysis, and visual inspection to ensure freedom from internal and surface defects before entering the production line.

2. Piercing and Hot Rolling

For seamless tubes, billets are heated to 1,200–1,250 °C (2,192–2,282 °F) and pierced using a Mannesmann-type or plug-type piercing mill to form hollow blanks. The blanks are subsequently hot-rolled to approximate dimensions.

3. Cold Drawing / Cold Rolling

Hot-rolled blanks are pickled, annealed, and then cold-drawn or cold-rolled to achieve precise final dimensions with tight tolerances. This cold-working step significantly improves surface finish, dimensional accuracy (typically ±0.1 mm on OD), and mechanical properties. For welded tubes, precision-rolled steel strips are formed and welded using TIG or ERW processes.

4. Heat Treatment (Annealing)

Tubes are annealed in a controlled atmosphere furnace at 1,050–1,100 °C (1,922–2,012 °F) followed by controlled cooling to restore ductility, relieve residual stresses, and achieve the desired microstructure. For 304L and 316L grades, a final solution treatment ensures maximum corrosion resistance.

5. Surface Treatment

Depending on the customer specification, tubes undergo acid pickling, passivation, or mechanical polishing to achieve the required surface finish — from industrial 2B to mirror-polished surfaces with Ra ≤ 0.1 μm.

6. Coil Forming and Straightening

Finished tubes are precisely coiled on dedicated winding equipment to produce uniform, undamaged coils. Straightening passes ensure dimensional consistency along the tube length before final coiling.

7. Final Quality Inspection

Every coil undergoes comprehensive testing including dimensional verification (OD, wall thickness, straightness), hydrostatic pressure testing, eddy current inspection, and visual examination. Chemical composition analysis and mechanical property testing (tensile strength, yield strength, elongation) are performed on sampled specimens.

Applications

Main Pipeline Systems

The large-diameter coil tubes are the preferred choice for main pipeline networks in chemical processing plants, oil refineries, power generation facilities, and desalination plants. Their superior corrosion resistance and mechanical strength ensure reliable long-term operation under high pressure and temperature conditions.

Long-Distance Fluid Transport

In applications requiring extended fluid transport runs — such as interconnecting process units, long-span utility lines, and underground distribution networks — the coil form enables continuous, joint-free installation that minimizes leak points and maintenance requirements. The ability to deliver coils up to 1,500 m (4,921 ft) reduces field welding and connection points significantly.

Large Heat Exchanger Coil Tubes

These tubes are extensively used in the fabrication of spiral-wound heat exchangers, shell-and-tube exchangers with large-bore tubes, air coolers, condensers, and evaporators. The large diameter facilitates higher flow rates and improved heat transfer efficiency, while the stainless steel material ensures resistance to thermal cycling and corrosive process fluids.

Additional Applications

Quality Certifications

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system certified to the following international standards:

Each batch of large-diameter coil tubes is accompanied by a full documentation package including mill test certificates (MTC), heat number traceability records, dimensional inspection reports, and non-destructive testing (NDT) results. Third-party inspection (TPI) by agencies such as SGS, Bureau Veritas, or TÜV is available upon customer request.

Unique Selling Points

Why Choose Wenzhou Jixing Large-Diameter Coil Tubes?