Stainless Steel Coil Tube for Organic Heat Transfer Fluid (OHTF) Furnaces

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 use in Organic Heat Transfer Fluid (OHTF) furnace systems. These coil tubes serve as critical heat exchange elements in industrial thermal processes, where they circulate organic heat transfer media to achieve uniform and controlled temperature distribution. The product is engineered to withstand prolonged exposure to elevated temperatures, thermal cycling, and corrosive environments inherent in chemical processing, polymer manufacturing, and petrochemical applications.

This coil tube product line integrates advanced acoustic emission (AE) detection technology into its quality assurance framework, ensuring structural integrity and operational reliability throughout the service life of the furnace system.

Material & Properties

Base Material Grades

Key Mechanical Properties

Corrosion Resistance

Specifications

Parameter Specification Standard/Reference
Tube Outer Diameter (OD) 12.7 mm – 168.3 mm (0.5" – 6.5") ASTM A213 / EN 10216
Wall Thickness 1.5 mm – 12.0 mm ASTM A213 / GB/T 14976
Coil Diameter (Bundle) 800 mm – 3000 mm Custom per furnace design
Coil Length (per bundle) 15 m – 120 m Custom per furnace design
Surface Finish 2B / No.4 / Electropolished (Ra ≤ 0.4 μm) ASTM A480
Heat Treatment Condition Solution Annealed + Water Quenched ASTM A213
Operating Pressure 0.1 MPa – 2.5 MPa (design) ASME Section VIII
Operating Temperature Range -20°C to +400°C (typical OHTF service) —
Maximum Design Temperature 600°C (310S grade available up to 1150°C) —
Welding Method TIG (GTAW) / Orbital Automatic Welding ASME Section IX / EN ISO 15614
End Forming Plain end / Beveled / Threaded / Flanged ASME B1.20.1
Acoustic Emission Inspection 100% coverage per bundle ASTM E1316 / ISO 13623

Manufacturing Process

1. Raw Material Selection and Verification

Stainless steel strip or pipe blanks are procured from certified mills with full material traceability. Each lot undergoes spectrographic analysis (PMI) to verify chemical composition within specified limits per ASTM A240 or equivalent standards. Incoming material is accompanied by mill test certificates (MTC) conforming to EN 10204 3.1 or 3.2.

2. Pipe Forming

Coil tubes are manufactured using one of the following processes:

3. Coil Bending and Forming

Finished tubes are cold-bent into the required coil geometry using CNC-controlled bending machines. The bending radius is carefully calculated to prevent wall thinning below the minimum allowable thickness (typically ≥ 85% of original wall thickness at the inner bend radius). Cold-work hardening effects are managed through intermediate annealing cycles when necessary.

4. Welding and Assembly

Coil tube bundles are assembled with headers and transition pieces using orbital TIG welding. Weld parameters are optimized for each joint configuration, with full welder qualification per ASME Section IX or EN ISO 9606-1. Weld quality is verified through:

5. Solution Annealing and Passivation

The completed coil assembly undergoes solution annealing at 1050–1150°C followed by rapid water quenching to restore full austenitic structure and maximum corrosion resistance. Post-annealing passivation treatment (nitric acid or citric acid) removes surface contamination and establishes a stable chromium oxide passive film.

6. Acoustic Emission (AE) Inspection

As a distinguishing quality assurance feature, each coil tube bundle undergoes comprehensive Acoustic Emission (AE) testing in accordance with ASTM E1316 and ISO 13623 standards. This non-destructive testing (NDT) methodology detects sub-surface defects, micro-cracks, and stress concentrations that may not be visible through conventional inspection methods. The AE inspection protocol includes:

Applications

Primary Applications

Operating Environment Characteristics

These coil tubes are specifically engineered for environments involving:

Quality Certifications and Compliance

Product Standards

Quality Management Systems

Non-Destructive Testing (NDT) Standards

Unique Selling Points

1. Integrated Acoustic Emission Quality Assurance: Unlike conventional coil tube manufacturers that rely solely on radiographic and ultrasonic testing, Wenzhou Jixing Metal Materials Co., Ltd. employs Acoustic Emission (AE) inspection as a supplementary NDT method. This technology provides real-time detection of active defects and stress concentrations under pressurized conditions, offering superior sensitivity to growing flaws that may develop during service.

2. Full Traceability: Every coil tube bundle is traceable from raw material mill heat number through final inspection, with complete documentation including material certificates, weld maps, NDT reports, and dimensional inspection records.

3. Custom Engineering Capability: Coil geometry, tube specifications, and bundle configurations are tailored to specific furnace designs and process requirements, with engineering support for thermal analysis, flow simulation, and fatigue life prediction.

4. Extended Service Life: The combination of premium material selection, controlled manufacturing processes, and comprehensive NDT ensures coil tube bundles that exceed industry-standard service life expectations, reducing unplanned downtime and maintenance costs.

Technical Documentation Provided