Seamless Coil Tube (Coiltube) — Technical Product Specification
1. Product Overview
The Seamless Coil Tube (Coiltube) is a precision-engineered tubular product supplied in continuous coiled form, manufactured without weld seams through advanced piercing and cold-drawing processes. Produced by Wenzhou Jixing Metal Materials Co., Ltd., this product line encompasses both stainless steel and copper alloy seamless coil tubes, designed for demanding industrial applications requiring superior mechanical integrity, corrosion resistance, and dimensional accuracy. The coiled delivery format eliminates the need for field welding during installation, significantly reducing labor costs and ensuring continuous structural homogeneity along the entire tube length.
Unlike conventional straight-length seamless tubes, coil tubes offer inherent flexibility during transportation and installation, making them ideal for applications requiring long, uninterrupted runs without joints. The product conforms to international standards including ASTM, ASME, EN, JIS, and GB specifications, reflecting compliance with global quality frameworks.
2. Material & Properties
2.1 Available Material Grades
- Stainless Steel Grades: AISI 304, 304L, 316, 316L, 321, 310S, 316Ti, 904L, 2205 (Duplex), 2507 (Super Duplex)
- Copper Alloy Grades: CuNi 90/10, CuNi 70/30, C70600, C70700, C70250, C72900 (Monel 400)
- Carbon Steel Grades: ASTM A53 Gr.B, ASTM A106 Gr.B, EN 10216-2
2.2 Key Mechanical Properties
- Tensile Strength (UTS): 515–830 MPa (depending on grade and temper condition)
- Yield Strength (0.2% Offset): 205–550 MPa
- Elongation: ≥30% (minimum, at rupture)
- Hardness: 90–350 HV (depending on temper condition)
- Corrosion Resistance: Excellent resistance to pitting, crevice, and intergranular corrosion (particularly 316L and duplex grades)
2.3 Physical Properties
- Density: 7.93 g/cm³ (Stainless Steel); 8.94 g/cm³ (Copper Alloys)
- Thermal Conductivity: 14.9–31.6 W/(m·K) (Stainless Steel); 17–21 W/(m·K) (CuNi Alloys)
- Maximum Service Temperature: −196°C to +1100°C (grade-dependent)
- Surface Finish: 2B (Mill Annealed), BA (Bright Annealed), No. 4 Brushed, 2D
3. Specifications
| Parameter | Specification Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 219.1 mm (¼" – 8") | ASTM A213 / A269 / EN 10216-5 |
| Wall Thickness (WT) | 0.5 mm – 12.0 mm | ASTM A213 / A269 |
| OD Tolerance | ±0.5% (Precision) / ±1.0% (Standard) | ASTM A213 |
| Wall Thickness Tolerance | ±10% (Standard) / ±5% (Precision) | ASTM A213 |
| Coil Length | 15 m – 50 m (standard); up to 100 m (custom) | Manufacturer Specification |
| Coil Inner Diameter | 200 mm – 600 mm | Manufacturer Specification |
| Temper Condition | Annealed (A), Half-Hard (H), Hard (H90, H95) | ASTM A269 / EN 10217 |
| End Treatment | Plain, Beveled, Flanged, Threaded, or Custom | ASME B16.11 / B16.12 |
| Surface Treatment | Pickled & Passivated, Electropolished, Brushed | ASTM A967 |
| Applicable Standards | ASTM A213, A269, A219, A214; EN 10216-5, 10217-7; JIS G3459; GB/T 12771 | — |
| Pressure Rating | Up to 40 MPa (PN40) depending on OD, WT, and material | ASME B31.3 / B31.1 |
| Packaging | Wooden pallet with steel strapping, protective end caps, moisture-proof wrapping | ISO 4180 |
4. Manufacturing Process
The production of seamless coil tubes follows a rigorously controlled multi-stage manufacturing process, ensuring dimensional precision and metallurgical integrity at every step:
- Raw Material Selection & Inspection: High-purity ingots or billets are selected based on chemical composition requirements. Incoming materials undergo spectroscopic analysis (OES — Optical Emission Spectroscopy) and ultrasonic testing (UT) to verify homogeneity and absence of internal defects.
- Hot Piercing: The solid billet is heated to a controlled temperature (1100–1250°C for stainless steel) and pierced using a mandrel-driven rotary piercing mill to form a seamless hollow tube blank. This process ensures a fully homogeneous microstructure without weld seams.
- Hot Rolling / Elongation: The pierced tube blank is hot-rolled to reduce the wall thickness and achieve preliminary dimensions while maintaining the seamless integrity of the tube.
- Heat Treatment (Solution Annealing): Tubes are solution-annealed in a controlled atmosphere furnace (typically 1050–1150°C for austenitic stainless steels) followed by rapid quenching to achieve the desired austenitic microstructure, eliminate residual stresses, and maximize corrosion resistance.
- Cold Drawing / Cold Pilgering: Tubes are cold-drawn through precision-die sets to achieve final dimensional tolerances (OD and WT within ±0.5% and ±10% respectively). This cold working also enhances surface finish quality and mechanical properties.
- Intermediate Annealing: Where multiple cold-drawing passes are required, intermediate annealing cycles restore ductility to prevent cracking during subsequent forming operations.
- Pickling & Passivation: Tubes are cleaned of oxide scale using acid pickling solutions (HNO₃/HF blend) and subsequently passivated to form a protective chromium oxide layer, ensuring optimal corrosion resistance.
- Coiling: Finished tubes are coiled using hydraulic coil winding equipment with controlled tension to prevent deformation, kinking, or surface damage. Coil dimensions are adjusted based on customer requirements and transport logistics.
- Final Quality Control & Inspection: Each coil undergoes comprehensive testing including hydrostatic pressure testing (typically 5.0–10.0 MPa), ultrasonic flaw detection, eddy current testing, dimensional verification, and surface inspection per ASTM A999 or equivalent.
- Packaging & Dispatch: Tubes are protected with end caps, wrapped in moisture-barrier material, and secured on wooden pallets with steel strapping for safe international shipping.
5. Applications
Seamless coil tubes find extensive application across multiple high-value industries due to their superior mechanical properties, corrosion resistance, and the elimination of weld joints:
5.1 Petroleum & Natural Gas Industry
- Downhole tubing and casing for oil and gas wells
- Subsea flow lines and umbilicals
- Refinery heat exchanger tubes and process piping
- Wellhead equipment and Christmas tree assemblies
5.2 Chemical & Pharmaceutical Processing
- Reactors, condensers, and evaporators
- Hygienic-grade process piping (316L, electropolished)
- Corrosive chemical transport lines
- Pharmaceutical CIP (Clean-in-Place) systems
5.3 Marine & Offshore Engineering
- Heat exchangers and condensers in ship propulsion systems
- Ballast water treatment systems
- Offshore platform piping systems (CuNi alloys for seawater resistance)
- Propeller shafts and marine hardware
5.4 Food & Beverage Industry
- Hygienic-grade dairy and beverage processing lines
- Wine and spirits production equipment
- Steam lines and condensate return systems
5.5 Power Generation
- Boiler tubes and superheater elements
- Condenser tubes in thermal power plants
- Nuclear-grade instrumentation tubing
5.6 Aerospace & Defense
- Hydraulic and fuel system lines
- Structural tubing in aircraft frames
- Jet engine fuel and oil lines
6. Quality Certifications & Testing
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and holds the following certifications:
| Certification | Scope |
|---|---|
| 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 (Third-party verified) |
| ASME "S" Stamp | Pressure Vessel & Piping Component Manufacturer |
| NADCAP (if applicable) | Aerospace Special Process Certification |
| PED 2014/68/EU | European Pressure Equipment Directive Compliance |
| CRN (Canadian Registration) | Canadian Pressure Equipment Registration |
6.1 Testing & Inspection Protocols
- Chemical Analysis: Full spectroscopic analysis per ASTM E415, verifying compliance with grade-specific compositional requirements (C, Cr, Ni, Mo, Mn, Si, P, S, etc.)
- Mechanical Testing: Tensile testing per ASTM A370, verifying UTS, yield strength, and elongation values
- Hydrostatic Testing: 100% hydrostatic pressure testing per ASTM A530, typically at 5.0–10.0 MPa with minimum hold time of 30 seconds
- Ultrasonic Testing (UT): Per ASTM A398 / EN 10229, detecting internal defects (laminations, inclusions, cracks)
- Eddy Current Testing (ECT): Per ASTM E709, detecting surface and near-surface defects
- Dimensional Inspection: OD, WT, roundness, and straightness verification using calibrated instruments
- Pitting Resistance Testing: ASTM A967 passivation verification and ASTM G48 pitting potential testing for stainless steel grades
- Intercalendary Testing: Periodic third-party laboratory verification by NDT (Notified Body) accredited organizations
7. Unique Selling Points
- Seamless Construction: Complete elimination of weld seams ensures uniform metallurgical properties throughout the tube cross-section, maximizing pressure containment capability and fatigue resistance.
- Coiled Delivery Format: Continuous coil supply eliminates field welding, reducing installation costs by up to 40% and ensuring zero joint-related failure points in critical applications.
- Wide Material Range: Availability in over 30 material grades covering stainless steel, copper alloys, and carbon steel meets diverse application requirements from a single source.
- Precision Dimensional Accuracy: Cold-drawing processes achieve tolerances as tight as ±0.5% on OD and ±5% on wall thickness, suitable for high-precision instrumentation and hydraulic applications.
- Full Traceability: Every coil is accompanied by a complete EN 10204 3.1 material test certificate with full heat