Stainless Steel Coil Tube for Oilfield Vehicle-Mounted Steam Dewaxing Systems
Product Overview
The stainless steel coil tube (Coil Tube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a specialized heat exchange and fluid conveyance component engineered for demanding oilfield applications. This product is specifically designed for integration into vehicle-mounted steam dewaxing trucks (油田车载蒸汽清蜡车), where it functions as a critical element in acid washing and descaling apparatus (酸洗除垢装置). The coil tube facilitates efficient thermal transfer, chemical fluid circulation, and scale removal operations in harsh, high-temperature environments typical of petroleum extraction and production facilities.
Unlike conventional straight stainless steel tubing, the coil tube geometry provides a significantly increased surface area-to-volume ratio, enabling superior heat exchange efficiency and enhanced chemical reaction kinetics within confined installation footprints. This makes the product indispensable for mobile oilfield equipment where space constraints and operational efficiency are paramount.
Material & Properties
Material Composition
The coil tube is fabricated from high-grade austenitic stainless steel, primarily conforming to the following material specifications:
- AISI 304 (UNS S30408): General-purpose corrosion resistance with excellent formability; chromium content ≥18%, nickel content ≥8%
- AISI 316L (UNS S31603): Enhanced resistance to pitting and crevice corrosion due to molybdenum addition (2–3% Mo); preferred for aggressive acid washing media
- AISI 321 (UNS S32100): Titanium-stabilized grade offering superior resistance to intergranular corrosion at elevated temperatures
Mechanical Properties
| Property | Specification (AISI 304) | Specification (AISI 316L) |
|---|---|---|
| Tensile Strength (抗拉强度) | ≥515 MPa | ≥485 MPa |
| Yield Strength (屈服强度) | ≥205 MPa | ≥170 MPa |
| Elongation (延伸率) | ≥40% | ≥40% |
| Operating Temperature Range (工作温度范围) | -196°C to +870°C | -196°C to +870°C |
| Corrosion Resistance (耐腐蚀性) | Excellent (atmospheric, mild acids) | Superior (chloride, marine, aggressive acids) |
Key Performance Characteristics
- High-temperature oxidation resistance: Maintains structural integrity under sustained steam exposure at temperatures exceeding 200°C
- Acid resistance: Withstands hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and organic acid solutions commonly used in descaling operations
- Fatigue resistance: Coil geometry inherently distributes cyclic thermal and mechanical stresses, extending service life under repeated operational cycles
- Non-magnetic properties: Austenitic microstructure ensures non-magnetic behavior, suitable for sensitive instrumentation environments
Specifications
| Parameter | Specification |
|---|---|
| Product Name (产品名称) | Stainless Steel Coil Tube (盘管) |
| Product Code (序号) | 657 |
| Outer Diameter (外径) | 6 mm – 50 mm (customizable) |
| Wall Thickness (壁厚) | 0.5 mm – 3.0 mm |
| Coil Pitch (盘管间距) | 15 mm – 60 mm (configurable) |
| Coil Diameter (盘管直径) | 100 mm – 500 mm |
| Total Tube Length (总管长) | 5 m – 50 m (custom orders available) |
| Surface Finish (表面光洁度) | 2B (mill finish), BA (bright annealed), or electropolished (Ra ≤ 0.4 μm) |
| End Connections (端部连接) | Welded fittings, threaded ends, or flanged connections |
| Pressure Rating (压力等级) | Up to 4.0 MPa (design pressure, dependent on dimensions) |
| Standards Compliance (标准符合) | ASTM A269, ASTM A312, EN 10217-7, GB/T 12771 |
Manufacturing Process
Process Flow
- Material Selection & Incoming Inspection: Cold-rolled stainless steel strip or seamless pipe undergoes chemical composition analysis (spectrometric verification) and mechanical property testing prior to processing.
- Coil Forming (盘绕成型): The tube is cold-coiled using precision CNC-controlled mandrel forming equipment. The forming process employs a controlled bend radius (typically 3D to 5D, where D = tube outer diameter) to prevent ovality deformation and wall thinning. Springback compensation algorithms ensure dimensional accuracy.
- Heat Treatment & Annealing (热处理与退火): Post-forming solution annealing is conducted at 1050°C – 1150°C followed by controlled cooling to restore full austenitic microstructure, eliminate residual stresses, and maximize corrosion resistance.
- Pickling & Passivation (酸洗钝化): The coil tube is subjected to a multi-stage pickling process using a mixed acid solution (HNO₃/HF) to remove oxide scale, followed by passivation treatment to establish a protective chromium oxide layer (Cr₂O₃) on the surface.
- End Preparation & Fitting Installation: Tube ends are cut, deburred, and prepared for welding or mechanical connection. Fittings (tees, elbows, flanges) are TIG-welded (GTAW) using matching filler wire to ensure metallurgical compatibility.
- Pressure Testing & Non-Destructive Testing (NDT): Each unit undergoes hydrostatic pressure testing at 1.5× design pressure and visual inspection. Optional penetrant testing (PT) or eddy current testing (ECT) verifies weld integrity.
- Final Inspection & Packaging: Dimensional verification, surface quality assessment, and material traceability documentation are completed before protective packaging for shipment.
Quality Control Measures
- In-process dimensional monitoring at critical forming stages (ovality control ≤ 1% of OD)
- Chemical spot-check verification per ASTM E415 (OES analysis)
- Hardness testing per ASTM E18 (Rockwell B scale) to confirm annealing adequacy
- Intergranular corrosion testing per ASTM A262 Practice E (acid solution test) for 316L grade
Applications
Primary Application: Oilfield Vehicle-Mounted Steam Dewaxing (油田车载蒸汽清蜡)
The coil tube serves as the core heat exchange and chemical circulation component in mobile steam dewaxing vehicles deployed at oil wells and production facilities. Its functions include:
- Steam heat generation and transfer: The coiled geometry maximizes heat dissipation from steam to paraffin wax deposits on well tubing, facilitating efficient wax removal at the wellbore level.
- Acid washing fluid circulation (酸洗液循环): The coil tube acts as a conduit for circulating acid descaling solutions through the well system, dissolving mineral scale (CaCO₃, BaSO₄) and heavy metal sulfide deposits.
- Chemical reaction chamber: The extended residence time within the coil enhances the contact duration between descaling agents and scale deposits, improving removal efficiency.
Secondary Applications
- Industrial heat exchangers for chemical processing
- Pharmaceutical and food-grade fluid processing systems
- Solar thermal energy collection systems
- Automotive and aerospace exhaust aftertreatment components
- Refrigeration and HVAC coil assemblies
Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent manufacturing processes |
| ISO 14001:2015 | Environmental Management System certification |
| API 5L / API 5CT | American Petroleum Institute compliance for oilfield service applications |
| CE Marking (PED 2014/68/EU) | European Pressure Equipment Directive compliance for pressure-containing components |
| NACE MR0175 / ISO 15156 | Resistance to sulfide stress cracking in oil and gas production environments |
| Mill Test Certificate (MTC) | EN 10204 3.1 certification with full traceability documentation |
Unique Selling Points
1. Purpose-Engineered for Oilfield Mobile Applications: Unlike generic coil tubing, this product is specifically validated for the extreme conditions of vehicle-mounted steam dewaxing systems—combining high-temperature steam resistance with aggressive acid media compatibility in a mobile, space-constrained configuration.
2. Superior Corrosion Performance: The 316L grade option with molybdenum enrichment provides exceptional resistance to chloride-induced pitting and acid attack, dramatically extending service intervals in harsh oilfield environments where 304-grade alternatives would suffer premature failure.
3. Precision Coiling Technology: CNC-controlled forming ensures uniform coil geometry with minimal springback variation, guaranteeing consistent heat transfer performance and predictable fluid dynamics throughout the product lifecycle.
4. Full Traceability & Documentation: Every coil tube unit is accompanied by complete material traceability documentation, including mill certificates, heat treatment records, and pressure test reports—essential for compliance audits in regulated oilfield operations.
5. Customization Capability: Wenzhou Jixing Metal Materials Co., Ltd. offers fully customizable coil dimensions, configurations, and end-connection types to match specific vehicle-mounted system designs, reducing integration engineering effort for OEM partners.
Technical Notes & Recommendations
- For applications involving hydrochloric acid (HCl) concentrations exceeding 10% by volume, AISI 316L is strongly recommended over 304 due to superior pitting resistance.
- Operating temperatures above 450°C may require 321 or 347 (stabilized) grades to prevent sensitization and intergranular corrosion.
- Regular inspection of weld joints is recommended after every 500 operating cycles to detect potential stress corrosion cracking initiation sites.
- Storage should be in a dry environment with separation from carbon steel materials to prevent galvanic contamination and staining.