Stainless Steel Coil Tube for Crude Oil Heater Applications
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product specifically designed for high-temperature, high-pressure environments within crude oil heating systems. These coil tubes serve as critical heat exchange elements in crude oil heater furnaces, where they endure extreme thermal cycling, corrosive media exposure, and mechanical stress over extended operational lifecycles. The product integrates advanced metallurgical formulation with rigorous manufacturing tolerances to ensure superior resistance against coking, oxidation, and thermal fatigue — challenges extensively documented in the research literature on crude oil heater coil tube cleaning and maintenance.
Based on extensive field research and application studies, particularly those addressing fouling, coke deposition, and cleaning methodologies in crude oil heater systems, Wenzhou Jixing Metal Materials has developed coil tubes that minimize scaling accumulation and extend cleaning intervals, thereby reducing unplanned shutdowns and maintenance costs in upstream and midstream petroleum processing facilities.
Material & Properties
The coil tubes are fabricated from austenitic and austenitic-ferritic stainless steel grades selected for their exceptional combination of high-temperature strength, thermal stability, and resistance to sulfidation and corrosion. The following material grades are commonly available:
- SAE 310 / S31008 — High-temperature austenitic stainless steel with excellent oxidation resistance up to 1150°C (2094°F), suitable for the hottest zones of crude oil heater radiant sections.
- SAE 321 / S32108 — Molybdenum-stabilized austenitic grade offering superior resistance to intergranular corrosion and thermal cycling fatigue.
- SAE 347 / S34708 — Niobium-stabilized austenitic stainless steel with enhanced resistance to sigma phase formation at elevated temperatures.
- SAE 310S / S31008 (modified) — Improved weldability variant of 310, offering reduced carbon content for better weld zone performance.
- SAE 660 / 17-4PH (for high-pressure applications) — Precipitation-hardening martensitic stainless steel for applications requiring elevated mechanical strength at moderate temperatures.
- SAE 304 / S30408 and SAE 316 / S31608 — General-purpose austenitic grades for convective sections and lower-temperature process connections.
Mechanical Properties (Typical Values at Elevated Temperatures)
| Property | SAE 310S | SAE 321 | SAE 347 | SAE 316 |
|---|---|---|---|---|
| Tensile Strength (RT), MPa (ksi) | ≥550 (79) | ≥520 (75) | ≥520 (75) | ≥520 (75) |
| Tensile Strength (1000°C), MPa (ksi) | ≥100 (14.5) | ≥90 (13) | ≥90 (13) | — |
| Yield Strength (0.2% offset, RT), MPa (ksi) | ≥205 (30) | ≥205 (30) | ≥205 (30) | ≥205 (30) |
| Elongation (RT), % | ≥40 | ≥40 | ≥40 | ≥40 |
| Thermal Expansion (20–1000°C), ×10⁻⁶/°C | 18.0 | 16.9 | 17.0 | 17.3 |
| Thermal Conductivity (1000°C), W/(m·K) | 35 | 29 | 29 | — |
| Maximum Service Temperature, °C | 1150 | 870 | 870 | 595 |
| Chromium Content, wt% | 24–26 | 17–19 | 17–19 | 16–18 |
| Nickel Content, wt% | 19–22 | 9–12 | 9–13 | 10–14 |
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Code | No. 461 — Coiltube |
| Material Grades | SAE 310S, 321, 347, 316, 304, 660 (customizable) |
| Outer Diameter (OD) | 25 mm – 168 mm (1" – 6.5") |
| Wall Thickness | 2.0 mm – 12.0 mm (0.079" – 0.472") |
| Tube Length (per coil) | 6 m – 12 m (20 ft – 40 ft) standard; up to 18 m custom |
| Coil Diameter | 1.5 m – 3.0 m (5 ft – 10 ft) |
| Manufacturing Method | Seamless (hot-rolled / cold-drawn) or welded (TPAW / GTAW) |
| Surface Finish | Pickled & Passivated (P&P), polished (Ra ≤ 0.4 μm available) |
| Pressure Rating | Up to 35 MPa (5075 psi) depending on grade and dimensions |
| Temperature Range | −196°C to 1150°C (−320°F to 2094°F) |
| Standards Compliance | ASTM A213, ASTM A269, ASME SA-213, ASME SA-269, EN 10216-5, GB/T 14976 |
| Welding Method | Transverse Pulse Arc Welding (TPAW) or Gas Tungsten Arc Welding (GTAW) with back purging |
| Heat Treatment | Solution Annealing (1050–1150°C), Stress Relief (800–900°C) |
| End Condition | Plain ends, beveled ends, or threaded per customer specification |
| Coiling Direction | Left-hand or right-hand coil, customer-specified |
| Minimum Order Quantity | 1 coil (subject to material grade and dimensions) |
Manufacturing Process
The production of Wenzhou Jixing Metal Materials' coil tubes follows a meticulously controlled multi-stage process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: High-purity stainless steel billets or seamless tubes are sourced from certified mills, with incoming material subjected to spectroscopic analysis (OES) and chemical composition verification against ASTM/ASME specifications.
- Hot Rolling or Extrusion: Billets are heated to forging temperature (1100–1200°C) and processed through rolling mills or extrusion presses to form seamless tube blanks with preliminary dimensions.
- Piercing and Elongation: The tube blanks undergo piercing to create the hollow section, followed by elongation passes to achieve the target outer diameter and wall thickness.
- Solution Annealing: Tubes are solution-annealed at 1050–1150°C and rapidly quenched in air or water to achieve a uniform austenitic microstructure free of carbide precipitation.
- Pickling and Passivation: The annealed tubes are immersed in a hydrofluoric-nitric acid pickling bath to remove oxide scale, followed by passivation treatment to establish a protective chromium oxide film on the surface.
- Cold Drawing (if applicable): For precision dimensions and improved surface finish, tubes pass through cold-drawing dies with intermediate annealing steps to reduce work hardening.
- Welding (for welded coil tubes): Transverse Pulse Arc Welding (TPAW) or Gas Tungsten Arc Welding (GTAW) with argon back purging is employed to achieve full-penetration, low-residual-stress welds meeting ASME SA-269 requirements.
- Coiling: Finished tubes are coiled on precision mandrels using hydraulic coiling machines to achieve uniform coil diameter and consistent curvature without introducing plastic deformation or surface damage.
- Non-Destructive Testing (NDT): Every coil tube undergoes comprehensive inspection including eddy current testing (ECT), ultrasonic testing (UT), and helium or pneumatic leak testing to verify weld integrity and detect subsurface defects.
- Final Dimensional Inspection: Outer diameter, wall thickness, straightness (for uncoiled sections), and coil diameter are verified against customer specifications using calibrated measuring instruments.
Applications
Wenzhou Jixing Metal Materials' stainless steel coil tubes are engineered for demanding applications in the petroleum, petrochemical, and process industries, with particular emphasis on crude oil heater systems:
- Crude Oil Heater Radiant Sections: Primary heat exchange tubes in atmospheric and vacuum distillation unit heater furnaces, where tube surfaces are exposed to crude oil feedstock at temperatures ranging from 400°C to 900°C. The tubes must resist coking, sulfidation, and thermal fatigue during continuous operation.
- Crude Oil Heater Convective Sections: Heat recovery tubes in the convection zone where flue gas temperatures range from 300°C to 600°C, requiring resistance to sulfur dioxide and sulfur trioxide corrosion.
- Reflux Drum and Overhead Line Heaters: Coil tubes used in overhead systems of distillation columns for maintaining process fluid temperatures.
- Vacuum Distillation Unit Heaters: High-temperature coil tubes operating under reduced pressure conditions with enhanced resistance to thermal creep.
- Process Heating Systems: General process heating applications in refineries, chemical plants, and power generation facilities.
- Feed Preheaters: Preheating of crude oil feed before entering distillation columns, utilizing coil tube heat exchange surfaces.
- Specialty Applications: Heat exchangers in the pharmaceutical, food processing, and aerospace industries where clean, corrosion-resistant heat transfer surfaces are required.
Key Application Insight: Research on crude oil heater coil tube cleaning has demonstrated that the selection of appropriate stainless steel grade, surface finish, and tube geometry significantly influences coke deposition rates and cleaning frequency. Wenzhou Jixing Metal Materials' coil tubes are engineered with surface treatments and alloy compositions that minimize fouling accumulation, extending cleaning intervals by up to 40% compared to conventional carbon steel tubes and reducing overall maintenance costs.
Quality Certifications and Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and holds the following certifications and complies with the following international standards:
- ISO 9001:2015 — Quality Management System certification, ensuring consistent product quality through documented processes and continuous improvement.
- ISO 14001:2015 — Environmental Management System certification, demonstrating commitment to environmentally responsible manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management System certification.
- ASME "S" Stamp — Authorization for the manufacture of seamless and welded tubes to ASME Boiler and Pressure Vessel Code, Section I and Section VIII.
- API 5CT / API 5L — American Petroleum Institute compliance for tubing and pipe used in the oil and gas industry.
- ASTM International — Full compliance with ASTM A213 (seamless tubes for heat exchangers), ASTM A269 (welded tubes), and related specifications.
- EN 10216-5 — European standard for welded stainless steel tubes for pressure purposes.
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes for fluid transport.
- NORSOK M-650 — Norwegian standard for materials used in offshore petroleum and natural gas industries (upon request).
- PED (Pressure Equipment Directive) 2014/68/EU — European conformity assessment for pressure equipment components.
Unique Selling Points
- Research-Driven Design: Product specifications are informed by extensive field research on crude oil heater coil tube performance, fouling behavior, and cleaning methodologies, resulting in tubes that are optimized for real-world operating conditions.
- Extended Service Life: Advanced alloy formulations and surface treatments minimize coke deposition and corrosion rates, extending coil tube replacement intervals and reducing total cost of ownership (TCO).
- Customization Capability: Flexible manufacturing allows customization of material grade, dimensions, coil diameter, surface finish, and end preparation to meet specific project requirements.
- Comprehensive NDT: Every production lot undergoes multi-modal non-destructive testing, ensuring zero-defect delivery with full traceability from raw material to finished product.
- Global Standards Compliance: Products are manufactured to meet or exceed the requirements of ASTM, ASME, EN, GB, and API standards, facilitating acceptance in international markets.
- Technical Support: Dedicated engineering team provides application-specific material selection guidance, installation recommendations, and post-delivery technical consultation.
Testing and Inspection Protocol
To ensure product reliability and performance consistency, the following testing protocol is applied at each production stage:
| Test Method | Standard Reference | Acceptance Criteria |
|---|---|---|
| Chemical Analysis (OES/SMA) | ASTM E415 / ASTM E1019 |