Stainless Steel Coiltube for FCC Oil Slurry Heat Exchangers

Product Overview

This high-performance stainless steel coiltube (Coil Tube) is engineered specifically for use in Fluid Catalytic Cracking (FCC) Oil Slurry Heat Exchangers within petrochemical refining units. FCC oil slurry service represents one of the most demanding environments in refinery operations, characterized by sustained operating temperatures ranging from 300°C to 400°C, aggressive chemical media, and continuous mechanical erosion caused by suspended catalyst particles. The coiltube design leverages inherent turbulence-enhancing geometry to achieve superior heat transfer efficiency while maintaining structural integrity under extreme erosive conditions.

Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product line addresses the critical challenge of balancing thermal performance with resistance to high-velocity solid particle impingement, ensuring long service life and minimizing unplanned shutdowns in continuous-process refineries.

Unique Selling Points

• Erosion-Resistant Design: Thick-walled construction specifically engineered to withstand abrasive catalyst particle impingement at elevated temperatures, significantly extending operational life compared to standard-wall tubing.
• Enhanced Heat Transfer: The coiled geometry promotes internal turbulence, increasing the overall heat transfer coefficient by up to 30–50% compared to straight-tube equivalents, reducing exchanger footprint and capital expenditure.
• Material Optimization: Dual-grade offering (316L and 321) provides flexibility to match specific corrosion and thermal stability requirements of different FCC unit configurations.
• Flow Velocity Control Strategy: Integrated design guidelines for optimal velocity management to prevent erosive wear while maintaining thermal efficiency, supported by CFD (Computational Fluid Dynamics) validated performance data.
• Full Traceability: End-to-end material traceability from mill certification through final inspection, ensuring compliance with international refinery standards.

Material & Properties

Grade 316L (UNS S31603) — Low Carbon Austenitic Stainless Steel

Selected for its exceptional resistance to pitting and crevice corrosion in chloride-containing FCC oil slurry environments. The low carbon content (≤0.03% C) eliminates intergranular sensitization risk during prolonged high-temperature service.

• Chromium (Cr): 16.0–18.0%
• Nickel (Ni): 10.0–14.0%
• Molybdenum (Mo): 2.0–3.0%
• Carbon (C): ≤0.030%
• Maximum Continuous Service Temperature: 450°C
• Corrosion Resistance: Superior resistance to chlorides, sulfides, and organic acids present in FCC oil slurry

Grade 321 (UNS S32100) — Titanium-Stabilized Austenitic Stainless Steel

Chosen for applications demanding superior thermal stability and resistance to intergranular corrosion at sustained high temperatures. Titanium stabilization (Ti ≥ 5×C) provides excellent resistance to oxidation and scaling at 300–400°C operating conditions.

• Chromium (Cr): 17.0–19.0%
• Nickel (Ni): 9.0–13.0%
• Titanium (Ti): 5×C (minimum), typically 0.4–0.7%
• Carbon (C): ≤0.08%
• Maximum Continuous Service Temperature: 870°C (oxidation resistance)
• Thermal Stability: Excellent resistance to sensitization and intergranular attack during thermal cycling

Specifications

Parameter	Specification	Standard / Reference
Product Type	Stainless Steel Coil Tube (盘管)	—
Material Grades	ASTM A270 / A213 Type 316L or Type 321	ASTM A270, ASTM A213
Outside Diameter (OD)	19.05 mm – 76.20 mm (¾" – 3")	ASTM A53, ASME B36.19M
Wall Thickness	3.00 mm – 10.00 mm (Thick-walled)	ASME B36.19M Schedule 80S–160S
Coil Mean Diameter	Custom per application (typically 300–1200 mm)	Project-specific
Tube Length (Uncoiled)	Up to 12,000 mm continuous	—
Operating Temperature	300°C – 400°C (continuous)	—
Design Pressure	Up to 6.0 MPa (900 psi)	ASME BPVC Section VIII
Surface Finish	Mill finish or pickled & passivated (Ra ≤ 0.8 μm)	ASTM A380
Recommended Flow Velocity	≤ 2.0 m/s (oil slurry side); ≤ 4.0 m/s (utility side)	API RP 571, NACE MR0175
Erosion Allowance	≥ 1.5 mm minimum wall thickness remaining after erosion allowance	API 579 / FFS
Welding Process	Orbital TIG (GTAW) with argon back protection	ASME BPVC Section IX
Applicable Standards	ASME BPVC, API 660, ASTM A270/A213, EN 10217	—

Manufacturing Process

1. Raw Material Selection & Inspection: Seamless stainless steel tubes conforming to ASTM A270 or A213 are procured from certified mills. Incoming material undergoes spectrographic analysis (PMI), hardness testing, and visual inspection to verify chemical composition and mechanical properties.
2. Dimensional Verification: Tubes are inspected for OD, wall thickness, straightness, and surface condition using ultrasonic thickness gauges and optical measurement systems. Thick-wall specifications are confirmed to meet minimum erosion allowance requirements.
3. Cutting & End Preparation: Tubes are cut to specified lengths using precision sawing equipment. End faces are deburred, chamfered, and cleaned to prepare for orbital welding. Surface contamination is removed via solvent cleaning and passivation.
4. Coil Forming (Cold Bending): Tubes are cold-coiled to the required mean coil diameter using CNC-controlled coil forming machines. The forming process maintains dimensional accuracy within ±0.5% of nominal diameter while avoiding work-hardening that could compromise fatigue life. Interpass inspection confirms no cracking or distortion.
5. Orbital TIG Welding (GTAW): End joints are welded using automated orbital TIG welding with 100% pure argon back purge to prevent internal oxidation. Weld parameters are qualified per ASME BPVC Section IX, and each weld undergoes visual inspection and dye penetrant testing (PT) per ASTM E709.
6. Post-Weld Heat Treatment (if required): Solution annealing may be applied for Grade 321 to restore full austenitic microstructure and eliminate residual stresses, followed by water quenching.
7. Pickling & Passivation: The completed coiltube assembly undergoes chemical pickling (HNO₃/HF blend) and passivation treatment per ASTM A380 to remove weld discoloration, mill scale, and contaminants, establishing a protective chromium oxide film.
8. Final Non-Destructive Testing (NDT): Comprehensive inspection includes visual examination, magnetic particle testing (MT) for surface defects, eddy current testing (ET) for wall thickness verification, and hydrostatic pressure testing at 1.5× design pressure per ASME BPVC Section VIII.
9. Packaging & Shipping: Coiltubes are wrapped in protective film, padded with impact-resistant material, and shipped in wooden crates or steel containers to prevent mechanical damage during transit.

Applications

This coiltube product is purpose-designed for the following critical applications within FCC refining units:

• FCC Oil Slurry Heat Exchangers: Primary application — recovering heat from high-temperature FCC oil slurry (300–400°C) while resisting erosion from suspended zeolite-based catalyst particles.
• FCC Feed Preheaters: Heating FCC feed streams prior to entering the riser reactor, where thermal efficiency directly impacts unit conversion rates.
• Slurry Cooler / Quencher Systems: Managing thermal loads in downstream cooling circuits where abrasive media and corrosive environments coexist.
• Heat Integration Loops: Pinch-point heat exchangers in process integration networks where space constraints favor compact coiled geometries.

Quality Certifications & Compliance

• ISO 9001:2015 — Quality Management System certification for manufacturing operations
• ISO 14001:2015 — Environmental Management System compliance
• ASME "U" Stamp — National Board registration for pressure vessel components (where applicable)
• ASTM Material Certification — Full mill test reports (MTR) with chemical analysis, mechanical test data, and NDT records per ASTM A270/A213
• API 5CT / API 660 Compliance — For refinery service components
• NACE MR0175 / ISO 15156 — Resistance to sulfide stress cracking in sour service environments
• Third-Party Inspection (TPI) — Available upon request for Lloyd's Register (LR), Bureau Veritas (BV), DNV, or TUV certification
• Material Traceability — Complete heat-number traceability from raw steel mill through final product dispatch

Design Considerations for Erosion Control

Critical Engineering Note: In FCC oil slurry service, catalyst particle erosion is the primary degradation mechanism. The following design principles must be adhered to:

• Flow Velocity Limitation: Oil slurry-side velocity must not exceed 2.0 m/s to prevent erosive wear. This is approximately 40–50% lower than typical clean-fluid design velocities.
• Thick-Wall Selection: Minimum wall thickness of 3.0 mm is recommended, with an additional erosion allowance of 1.5 mm factored into the design life calculation.
• Smooth Internal Surface: Ra ≤ 0.8 μm internal surface finish reduces particle adhesion and minimizes local turbulence-induced erosion.
• Gradual Bend Radius: Coil mean diameter should be ≥ 8× tube OD to avoid excessive centrifugal particle impact at bends.
• Material Selection Guidance: Grade 316L is preferred for chloride-rich slurry; Grade 321 is preferred where thermal cycling and oxidation resistance are dominant concerns.

Wenzhou Jixing Metal Materials Co., Ltd. maintains a dedicated engineering team specializing in FCC service coiltube design, offering CFD simulation support, erosion life prediction, and application-specific material selection advisory to ensure optimal performance and maximum asset availability.