Stainless Steel Heating Coil Tube (Coiltube) — Product Technical Specification

Product Overview

Wenzhou Jixing Metal Materials Co., Ltd. manufactures high-performance stainless steel coil tubes (coiltubes) engineered for demanding industrial applications, particularly in the oil and gas processing sector. These coil tubes are designed as integral heating elements for three-phase separators and similar process equipment, where they provide reliable thermal management under continuous high-temperature and high-pressure operating conditions. The product is engineered to resist the complex corrosion mechanisms—including sulfide stress cracking, pitting, crevice corrosion, and high-temperature oxidation—that are prevalent in hydrocarbon processing environments.

The coiltube product line addresses critical failure modes identified in field studies, such as those documented in research on the Baolang Oilfield Joint Station three-phase separator heating coil tube corrosion analysis. By incorporating advanced material selection and manufacturing controls, these coil tubes significantly extend service life and reduce unplanned shutdowns in upstream and midstream oil and gas facilities.

Material & Properties

The coil tubes are fabricated from austenitic stainless steels selected for superior corrosion resistance, mechanical integrity at elevated temperatures, and weldability. Primary material grades include:

Key material properties include:

Specifications

Parameter Specification Range
Outer Diameter (OD) Φ 12 mm – Φ 89 mm (custom sizes available)
Wall Thickness 1.0 mm – 6.0 mm
Bend Radius ≥ 3D (3× outer diameter), minimum 1.5D for special applications
Coil Length Up to 200 m continuous coil; custom cut-to-length available
Surface Finish Pickled & Passivated (2A finish, Ra ≤ 0.8 μm); Polished finish optional
Manufacturing Standard ASTM A269 / ASTM A213 / GB/T 12771 / EN 10217-7
Heat Treatment Condition Solution Annealed (1050–1150°C), followed by controlled cooling
Pressure Rating Up to 25 MPa (depending on wall thickness and diameter)
Temperature Range −196°C to +870°C
Welding Compatibility Fully weldable; TIG (GTAW), Orbital, and Resistance welding methods compatible
End Preparation Plain ends, beveled ends, or thread-protected ends per customer specification

Manufacturing Process

The production of Wenzhou Jixing stainless steel coil tubes follows a rigorous, multi-stage manufacturing process to ensure dimensional accuracy, metallurgical integrity, and long-term corrosion performance:

  1. Raw Material Selection & Inspection — Ingot or strip stock is sourced from certified mills and subjected to spectrographic analysis (PMI), mechanical testing, and chemical composition verification in accordance with ASTM A269 and GB/T 12771.
  2. Cold Drawing / Seamless Forming — Tubes are drawn through precision dies to achieve exact outer diameter and wall thickness tolerances (±0.1 mm). Seamless processes eliminate weld seams, reducing potential corrosion initiation sites.
  3. Solution Annealing (Heat Treatment) — Tubes are heated to 1050–1150°C and rapidly cooled (air or water quench) to dissolve carbide precipitates, restore full austenitic structure, and maximize corrosion resistance. This step is critical for preventing intergranular corrosion.
  4. Pickling & Passivation — A chemical cleaning process removes mill scale, oxide films, and surface contaminants using nitric-hydrofluoric acid blend, followed by passivation to form a protective chromium oxide layer (Cr₂O₃) on the surface.
  5. Precision Coil Bending (Coiling) — Tubes are bent into helical coil configurations using CNC-controlled cold-bending machinery. Bend radius is controlled to ≥ 3D to prevent wall thinning, ovality, or cracking at bend points. Post-bend inspection includes dimensional verification and leak testing.
  6. Quality Inspection & Testing — Final products undergo comprehensive inspection including: hydrostatic pressure testing (1.5× working pressure), eddy current testing for internal/external defects, dimensional measurement, surface roughness profiling, and optional magnetic particle or penetrant testing at weld joints.
  7. Packaging & Delivery — Coiltubes are packaged with moisture-proof wrapping, anti-corrosion coatings on ends, and protective caps to prevent damage during transit. Each batch is accompanied by a Material Test Certificate (MTC) per EN 10204 Type 3.1.

Applications

Wenzhou Jixing stainless steel coil tubes are engineered for a wide spectrum of industrial applications where corrosion resistance, thermal performance, and mechanical durability are paramount:

Notable Application Case: The coil tube design and material selection principles are informed by field investigations such as the Baolang Oilfield Joint Station three-phase separator study, which identified sulfide-induced corrosion and high-temperature oxidation as primary degradation mechanisms. Wenzhou Jixing's coil tubes incorporate countermeasures—including molybdenum-enhanced grades, optimized wall thickness for thermal stress management, and surface passivation—to mitigate these failure modes.

Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications and compliances:

All products undergo non-destructive testing (NDT) and destructive sampling per ASTM A269/A213 and GB/T 12771 protocols. Full traceability is maintained from raw material mill certificates through final product dispatch, ensuring complete supply chain accountability.

Unique Selling Points