Stainless Steel Coil Tube (Coiltube) for Oil & Gas Dehydration Systems
Product Code: No. 888 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular component specifically designed for high-corrosion environments in oil and gas processing facilities. This product is primarily deployed within dehydration skid buffer tanks, where it functions as an integral heat exchange or flow distribution element. The coil tube is supplied in a coiled configuration to facilitate seamless integration into skid-mounted systems, minimizing on-site welding and reducing potential leak points in critical process lines.
Based on extensive field data and corrosion pattern analysis from major gas field operations — including the Jingbian Gas Field in Shaanxi Province, China — this coil tube product has been rigorously optimized to withstand the aggressive chemical environments encountered in natural gas dehydration processes, which include hydrogen sulfide (H₂S), carbon dioxide (CO₂), chloride ions (Cl⁻), and aqueous acid condensates.
2. Material & Properties
2.1 Base Material Grades
The coil tube is fabricated from high-performance austenitic and duplex stainless steel grades selected to address the specific corrosion mechanisms observed in dehydration skid buffer tank applications:
- 316L (UNS S31603) — Low-carbon austenitic stainless steel with molybdenum addition, offering superior resistance to pitting and crevice corrosion in chloride-rich environments.
- 321 (UNS S32100) — Titanium-stabilized austenitic stainless steel providing enhanced resistance to intergranular corrosion during welding and thermal cycling.
- 304L (UNS S30403) — General-purpose low-carbon austenitic stainless steel suitable for moderate corrosion conditions and cost-sensitive applications.
- Duplex 2205 (UNS S31803) — Duplex austenitic-ferritic stainless steel offering high mechanical strength (yield strength ≥ 450 MPa) and excellent resistance to stress corrosion cracking (SCC) in sulfide-containing media.
2.2 Key Mechanical Properties
| Property | 316L | 321 | 304L | Duplex 2205 |
|---|---|---|---|---|
| Tensile Strength (MPa) | ≥ 485 | ≥ 515 | ≥ 485 | ≥ 620 |
| Yield Strength (MPa, 0.2% offset) | ≥ 170 | ≥ 205 | ≥ 170 | ≥ 450 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 25 |
| Operating Temperature Range (°C) | −196 to +425 | −196 to +900 | −196 to +870 | −50 to +350 |
| Corrosion Resistance (Pitting Resistance Equivalent Number, PREN) | 26 | 19 | 19 | 35 |
2.3 Chemical Composition (Typical, wt%)
| Grade | C | Cr | Ni | Mo | Ti | N | Si | Mn |
|---|---|---|---|---|---|---|---|---|
| 316L | ≤ 0.03 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — | — | ≤ 1.0 | ≤ 2.0 |
| 321 | ≤ 0.08 | 17.0–19.0 | 9.0–12.0 | — | 5×C to 0.70 | — | ≤ 1.0 | ≤ 2.0 |
| 304L | ≤ 0.03 | 18.0–20.0 | 8.0–12.0 | — | — | — | ≤ 1.0 | ≤ 2.0 |
| 2205 | ≤ 0.03 | 22.0–23.0 | 5.5–8.0 | 3.0–3.5 | — | 0.14–0.20 | ≤ 1.0 | ≤ 2.0 |
3. Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | Φ14.0 mm – Φ168.3 mm (customizable) |
| Wall Thickness | 0.8 mm – 12.0 mm |
| Coil Inner Diameter (ID) | Φ300 mm – Φ1200 mm (adjustable per skid layout) |
| Coil Length | Up to 1,200 meters per coil (continuous coil) |
| Surface Finish | 2B (cold-rolled and annealed), BA (Bright Annealed), or Electropolished (Ra ≤ 0.4 μm) |
| Bend Radius (Minimum) | ≥ 3D (where D = outer diameter) |
| Pressure Rating | Up to 4.0 MPa (design pressure, subject to wall thickness and grade) |
| End Condition | Plain ends, beveled ends, or pre-welded fittings |
| Coating / Passivation | Acid passivation per ASTM A967; optional PTFE or ceramic internal coating |
| Applicable Standards | ASTM A213 / A269, ASME B36.19M, EN 10216-5, GB/T 13296 |
| Packaging | Wooden coil stand with moisture-proof wrapping; VCI (Volatile Corrosion Inhibitor) film protection |
4. Manufacturing Process
The coil tube is produced through a rigorous, multi-stage manufacturing pipeline designed to ensure dimensional accuracy, metallurgical integrity, and corrosion resistance:
- Raw Material Procurement & Verification: Virgin stainless steel strip or seamless pipe stock is sourced from certified mills and subjected to 100% chemical composition analysis (OES — Optical Emission Spectroscopy) and mechanical property testing.
- Cold Drawing / Seamless Forming: The tube blank is cold-drawn through precision dies to achieve exact outer diameter and wall thickness tolerances (±0.05 mm). Alternatively, seamless tubes are drawn over a mandrel for tight tolerance control.
- Continuous Coiling: The drawn tube is coiled around a precision mandrel at controlled tension to form a uniform coil shape. Tension and feed rate are computer-monitored to prevent ovality, kinking, or residual stress concentration.
- Stress Relief Annealing: The coiled tube undergoes a controlled heat treatment (typically 1050°C ± 10°C for austenitic grades, followed by water quench) to relieve cold-worked residual stresses, restore full solution-annealed microstructure, and maximize corrosion resistance.
- Acid Pickling & Passivation: Per ASTM A967, the coil is subjected to a hydrofluoric-nitric acid pickling bath to remove scale and oxide films, followed by a nitric acid passivation step to establish a stable, protective chromium oxide layer on the surface.
- Non-Destructive Testing (NDT):strong> Each coil undergoes 100% electromagnetic (Eddy Current) testing per ASTM E709 to detect wall thickness variations, longitudinal cracks, and subsurface defects. Radiographic testing (RT) is performed on weld seams where applicable.
- Dimensional Inspection: Laser-based dimensional measurement verifies outer diameter, wall thickness, ovality, and coil geometry against specified tolerances.
- Packaging & Dispatch: The finished coil is wound onto a heavy-duty wooden or steel coil stand, wrapped in VCI-impregnated film and moisture-barrier material, and labeled with a full traceability data sheet.
5. Applications
The stainless steel coil tube is engineered for demanding service conditions in the oil, gas, and petrochemical industries. Key application areas include:
- Dehydration Skid Buffer Tanks: Serves as a heat exchange coil or flow conditioning element within glycol (TEG — Triethylene Glycol) dehydration skids, where resistance to corrosive condensate and amine solutions is critical.
- Gas Processing Plants: Deployed in separator internals, knock-out drum coils, and gas conditioning modules at gas processing facilities.
- Upstream Production Systems: Used in wellhead flowback lines, subsea umbilical tie-ins, and Christmas tree manifolds requiring flexible, corrosion-resistant tubing.
- Chemical Processing: Suitable for acid storage tank internals, reactor jacket coils, and distillation column internals handling halogenated compounds.
- Marine & Offshore Platforms: Applied in ballast water treatment systems, fire water piping, and desalination plant heat exchanger bundles.
- Food & Pharmaceutical: Electropolished variants serve in sanitary-grade heat transfer coils for CIP (Clean-in-Place) compatible systems.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management and certification framework to ensure full compliance with international and industry standards:
- ISO 9001:2015 — Quality Management Systems certification, ensuring consistent production quality and process control.
- ISO 14001:2015 — Environmental Management Systems certification, covering environmentally responsible manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management Systems certification.
- API Q1 (API Spec Q1) — Quality Management System for Oil and Gas Industry, Manufacturing and Service Organizations.
- NACE MR0175 / ISO 15156 — Compliance for materials used in H₂S-containing environments in oil and gas production.
- ASTM / ASME Material Compliance: All products are certified to applicable ASTM and ASME specifications with full mill test reports (MTRs) and heat traceability.
- Third-Party Inspection (TPI): Available upon request by recognized inspection bodies including DNV, ABS, BV, and Lloyd's Register.
7. Unique Selling Points
- Field-Validated Corrosion Resistance: Product design and material selection are informed by real-world corrosion pattern data from major gas field dehydration facilities (e.g., Jingbian Gas Field), ensuring proven performance in the harshest service conditions.
- Continuous Coil Delivery: Supplied in long, uninterrupted coils — eliminating field welds and significantly reducing installation time and leak risk in critical process systems.
- Full Traceability: Every coil is accompanied by a complete heat-number-traceable mill test report (MTR), chemical analysis certificate, and NDT documentation.
- Customizable Geometry: Coil dimensions, bend radii, end preparations, and surface finishes can be tailored to specific skid or vessel layouts, reducing custom fabrication requirements on-site.
- Multi-Grade Selection: Four material grades (304L, 316L, 321, 2205) provide a cost-performance spectrum that allows engineers to optimize material selection based on specific corrosion severity, pressure rating, and budget constraints.
- End-to-End Manufacturing Control: From raw material verification through final NDT and packaging, the entire production chain is managed in-house, ensuring consistent quality and rapid delivery.
Note: All specifications listed above are typical values. Custom specifications, non-standard dimensions, or special material grades are available upon request. Wenzhou Jixing Metal Materials Co., Ltd. provides free engineering consultation and sample testing for project-specific qualification requirements.