Stainless Steel Coil Tube (Coiltube) — Flange-Connection Enhanced Series
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 1044) represents a high-performance continuous-length tubing solution engineered for demanding industrial piping and fluid conveyance applications. Unlike conventional straight-length stainless steel tubes, the coil tube is delivered in a continuous helical or spiral configuration, enabling on-site cold bending and forming without the introduction of heat-affected zones (HAZ) or weld seams at bends. This product line has been further enhanced through the incorporation of improved flange pipe connection methods, addressing longstanding challenges associated with traditional flange assemblies—including leakage risks, bolt preload inconsistency, and assembly complexity—thereby delivering superior sealing integrity, faster installation, and reduced lifecycle maintenance costs.
Key Innovation: The integration of an optimized flange connection architecture—featuring enhanced gasket seating geometry, improved bolt load distribution, and upgraded sealing surfaces—represents a significant advancement over conventional ISO 7005 / ASME B16.5 flange configurations, yielding measurable improvements in pressure containment reliability and thermal cycle durability.
2. Material & Properties
2.1 Base Material Grades
- ASTM A269 / A270 — Austenitic stainless steel tubing (304, 304L, 316, 316L, 321, 347H)
- ASTM A312 — Austenitic stainless steel welded and seamless tubing
- ASTM A778 — Austenitic stainless steel seamless tubing for high-temperature service
- Custom Alloy Options: 904L (ASTM B333), duplex 2205 (ASTM A790), and super-austenitic AL-6XN
2.2 Mechanical Properties (Typical for Grade 316L)
| Property |
Specification |
Test Standard |
| Tensile Strength (UTS) |
≥ 485 MPa (70,300 psi) |
ASTM A923 / ISO 13888 |
| Yield Strength (0.2% Offset) |
≥ 170 MPa (24,650 psi) |
ASTM A923 |
| Elongation (at Break) |
≥ 40% |
ASTM A923 / ISO 13888 |
| Hardness (Rockwell B) |
≤ 95 HRB |
ASTM E140 |
| Density |
8.00 g/cm³ |
— |
| Thermal Conductivity (20°C) |
16.3 W/(m·K) |
ASTM E1461 |
| Maximum Service Temperature |
870°C (1,598°F) |
— |
| Minimum Service Temperature |
−196°C (−321°F) |
— |
2.3 Corrosion Resistance
- Excellent resistance to pitting and crevice corrosion in chloride-containing environments (316L, Mo ≥ 2.0%)
- Outstanding intergranular corrosion resistance following sensitization at 800–850°C (low-carbon L grades, C ≤ 0.03%)
- Resistance to stress corrosion cracking (SCC) in dilute sulfuric and hydrochloric acid solutions
- Passive film self-healing capability in oxidizing environments (Cr ≥ 16%, Cr₂O₃ passive layer)
3. Specifications
3.1 Geometric Dimensions
| Parameter |
Range |
Notes |
| Outer Diameter (OD) |
6.35 mm – 219.08 mm (¼" – 8") |
ASTM A269 / A270 / A312 |
| Wall Thickness (WT) |
0.25 mm – 12.70 mm (0.010" – 0.500") |
±10% tolerance on WT |
| Coil Length (per Roll) |
30 m – 300 m (98 ft – 984 ft) |
Customizable upon request |
| Coil Core Diameter |
150 mm – 500 mm |
Adaptable to customer storage racks |
| Coil Outer Diameter |
≤ 2,000 mm |
For transport stability |
| Dimensional Tolerance (OD) |
±0.05 mm (≤ 25.4 mm OD); ±0.10 mm (> 25.4 mm OD) |
Per ASTM A213 / ASME B36.19M |
| Roundness |
≤ 0.10% of OD |
Per ASTM A213 |
| Flange Connection Type |
Weld Neck (WN), Slip-On (SO), Threaded (Thd), Lap Joint (LJ) |
ASME B16.5 / EN 1092-1 / ISO 7005-2 |
| Flange Pressure Rating |
PN10 – PN400 / Class 150 – Class 2500 |
ASME B16.5 |
3.2 Surface Finish Options
| Finish Type |
Surface Roughness (Ra) |
Application |
| Pickled & Passivated (P&P) |
0.5 – 1.6 μm |
General industrial piping |
| Mechanical Polished |
0.2 – 0.5 μm |
Food & beverage, pharmaceutical |
| Electrolytic Polished (EP) |
0.05 – 0.2 μm |
Semi-conductor, ultrapure fluid |
| Bead Blasted / Matte |
0.8 – 1.2 μm |
Architectural, decorative |
4. Manufacturing Process
4.1 Coil Tube Production Workflow
- Raw Material Receiving & Inspection: Stainless steel strip or wire rod is sourced from certified mills (e.g., Outokumpu, POSCO, Tsingshan). Incoming material undergoes spectroscopic verification (OES) and mechanical property testing prior to acceptance.
- Coil Winding (Continuous Forming): Seamless or welded tube is continuously formed and wound onto precision steel cores using automated coil-winding machines. The winding tension is controlled to prevent deformation, ovality, or inter-coil contact damage. Tension control accuracy: ±5% of set value.
- Heat Treatment (Annealing & Pickling): Tubes are subjected to solution annealing at 1,050–1,150°C followed by rapid water quenching to dissolve carbides and restore full austenitic structure. Subsequent pickling (HNO₃/HF blend) removes scale and re-establishes the chromium oxide passive film.
- Precision Sizing & Straightening: Multi-roller sizing stations ensure dimensional conformance to ±0.05 mm OD tolerance. Inline roundness and straightness gauges provide real-time feedback to the control system.
- Flange Connection Fabrication & Integration: The improved flange connection system is fabricated as a pre-welded or field-installable assembly. Key improvements include:
- Optimized gasket groove geometry with 3° included angle for enhanced radial compression
- Staggered bolt hole pattern to minimize localized stress concentration
- Hardened flange sealing face (HRC 30–35) for extended gasket life
- Integrated torque-limiting bolt features for repeatable assembly preload
- Non-Destructive Testing (NDT):
- Eddy Current Testing (ECT) per ASTM E3092 — 100% inline inspection of tube body
- Penetrant Testing (PT) per ASTM E165 — Flange weld seams and critical joints
- Ultrasonic Thickness Testing (UT) per ASTM E164 — Wall thickness verification
- Hydrostatic Pressure Testing per ASTM A269 — 1.5× design pressure, 30-second hold
- Final Inspection, Packaging & Dispatch: Each coil is tagged with a unique lot identifier, Mill Test Certificate (MTC), and dimensional traceability record. Coils are wrapped in VCI (Vapor Corrosion Inhibitor) film, sleeved in kraft paper, and shrink-wrapped with protective end caps for shipping.
5. Applications
- Oil & Gas Industry: Subsea umbilical tubing, downhole instrumentation conduit, chemical injection manifolds with flange-connected junction boxes
- Chemical Processing: Acid/alkali transfer lines, reactor feed piping, heat exchanger tube bundles with enhanced flange connections for high-pressure service
- Food & Beverage: CIP (Clean-In-Place) compatible dairy processing lines, beer brewing transfer tubing, edible oil transport systems
- Pharmaceutical & Biotechnology: GMP-compliant process piping, bioreactor feed lines, sterile fluid transfer with electropolished surfaces and improved flange seals
- Semi-Conductor Manufacturing: Ultra-high purity (UHP) gas delivery lines, ultrapure water (UPW) distribution, chemical mechanical polishing (CMP) fluid circuits
- Power Generation: Boiler feedwater lines, supercritical steam condensate return, nuclear-grade instrumentation tubing (316L/321H)
- Aerospace: Hydraulic and pneumatic conduit, fuel system tubing, engine cooling circuits with vibration-resistant flange assemblies
- Marine & Offshore: Ballast water systems, fire suppression lines, marine-grade duplex alloy (2205) seawater applications
6. Quality Certifications & Compliance
6.1 System & Product Certifications
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management System
- EN 10204 3.1 — Material Test Certificate (MTC) per European standard
- ASME Section IX — Welding qualification (flange connection welding procedures)
- API 5L / API 5CT — For oil and gas sector applications
- EN 10217-7 — Pressure equipment piping (PED 2014/68/EU compliance)
- 3-A Sanitary Standards — For food and pharmaceutical applications
- EHEDG — European Hygienic Engineering & Design Group compliance
- NSF 61 — Drinking water system component certification
6.2 Testing & Inspection Protocols
| Test Category |
Standard |
Frequency |
| Chemical Composition Analysis |
ASTM E1252 / E415 |
Per heat / per lot |
| Tensile Testing |
ASTM A923 / ISO 13888 |
Per heat |
| Impact Testing (Charpy V-Notch) |
ASTM E23 / ISO 148-1 |
Per heat (cryogenic service) |
| Intergranular Corrosion (IGC) |
ASTM A269 (Section 16) / ASTM G48 |
Per heat |
| Pitting Resistance (PREN) |
ASTM G48 Method A |
Per grade qualification |
| Flange Gasket Sealing Test |
ISO 15148-1 / EN 12266-1 |
Per connection design |
| Flame Spray / Burst Test |
ASTM A269 / EN 10217-7 |
Per batch (hydrostatic) |
| Dimensional & Surface Finish Audit |
ASTM A213 / ASME B36.19M |
100% inline |
7. Unique Selling Points
- Continuous-Length Advantage: The coil format eliminates butt-weld joints in straight runs, reducing potential failure points by up to 60% compared to standard pipe with flanged splices, and enabling complex on-site routing without thermal distortion.
- Enhanced Flange Connection Architecture: The proprietary improved flange connection design—incorporating optimized gasket seating geometry, staggered bolt patterns, and hardened sealing faces—delivers a 40% improvement in pressure containment reliability and 25% reduction in assembly time versus conventional flange joints.
- Full Traceability: Every coil is accompanied by a comprehensive Mill Test Certificate with heat-number traceability, chemical composition, mechanical properties, and NDT results, ensuring complete supply chain accountability.
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