Duplex Stainless Steel 2205 2507 Heat Exchanger Tube Bundle for High Pitting Resistance Offshore Chemical Facilities

Yuhong Group Co., Ltd. operates direct seamless pipe mills and heavy equipment manufacturing facilities, providing fully traceable raw tubing and engineered thermal core replacements. We specialize in fabricating high-strength, corrosion-resistant duplex heat exchanger tube bundle assemblies, straight and bent heat transfer tubing arrays, extended surface finned tube bundle cores, and heavy forged heat exchanger tubesheet plates for critical fluid process applications.

Operating under ISO 9001 quality management, Yuhong Group eliminates raw material procurement delays by utilizing in-house seamless tubing stock. We produce drop-in replacement cores for existing shell and tube heat exchanger and shell & tube heat exchanger vessels operating under severe thermal cycling, sour gas (H₂S), and high-chloride conditions.

Standard 304L/316L stainless steel cores frequently fail prematurely under elevated chloride concentrations (>1,000 ppm) due to Stress Corrosion Cracking (SCC) and localized pitting corrosion. Yuhong Group replaces compromised Austenitic cores with Duplex 2205 (UNS S31803 / S32205) and Super Duplex 2507 (UNS S32750) tube bundles.

• Yield Strength Limits: Minimum yield strength of 450 MPa (65 ksi for Duplex 2205), double that of standard Austenitic grades (205 MPa for 316L), permitting reduced tube wall thickness without sacrificing burst pressure safety margins.
• Pitting Resistance Equivalent Number (PREN): Calculated PREN value ≥ 35 for Duplex 2205 (%Cr + 3.3 %Mo + 16 %N) and ≥ 42 for Super Duplex 2507, preventing pitting in high-salinity process loops up to 150℃.
• Pressure & Temperature Thresholds: Engineered to sustain design pressures up to 25 MPa (3,625 psi) and fluid temperatures ranging from -50℃ to 300℃.

We fabricate custom replacement cores matching OEM mechanical dimensions across standard TEMA structural formats:

• Removable U Tube Bundle (TEMA U): Features bent tube arrays anchored to a single heat exchanger tubesheet. This design accommodates differential thermal expansion between shell and tubes without generating cyclic stress on tube-to-tubesheet joint welds.
• Floating Head Tube Bundle (TEMA S/T): Built with a stationary tubesheet and an internal floating head, permitting full core withdrawal for mechanical hydro-jetting in heavy crude oil service.
• Fixed Tubesheet Bundle (TEMA E/F): Rigid dual-tubesheet structure ideal for non-fouling process media or steady-state thermal duties.
• Extended Air Cooler Finned Modules: Integrates high-density finned tube bundle modules (extruded aluminum sleeve or embedded G-fin) onto Duplex base tubes for severe ambient air cooling installations.

• Duplex Stainless Steels: ASTM A789 / A790 UNS S31803, UNS S32205 (Duplex 2205), UNS S32750 (Super Duplex 2507), UNS S32304 (Lean Duplex 2304).
• Super Austenitic & Nickel Alloys: UNS N08904 (904L), UNS N08825 (Incoloy 825), UNS N06625 (Inconel 625), Hastelloy C276.

• Precision CNC Machining & Double Serration: Tubesheet hole patterns are machined on multi-axis CNC centers. Double-serrated grooving (0.4 mm depth * 1.6 mm width) enhances mechanical grip strength during hydraulic tube expansion.
• Automated Orbital Welding: Tube-to-tubesheet connections undergo automated TIG strength welding combined with torque-controlled expansion to guarantee zero-leakage joint reliability.
• Solution Annealing for Cold Bends: U-bend zones on all u tube bundle sets are solution heat-treated (1,020℃ to 1,100℃ followed by rapid water quenching) to restore phase balance (40%–60% ferrite/austenite) and eliminate residual stress.
• Factory NDT Inspections: 100% Non-Destructive Examination including Hydrostatic Pressure Testing (up to 1.5 times design pressure), Eddy Current Testing (ET), Radiographic Testing (RT) on pressure welds, Liquid Penetrant Testing (PT), and Positive Material Identification (PMI).

1. Phase Balance Verification: Ferrite content in Duplex welds and U-bend zones must be maintained between 35% and 65% according to ASTM E562. Excess ferrite (>70%) degrades impact toughness at low temperatures, while excess austenite lowers resistance to stress corrosion cracking.
2. Tube Layout Pitch Selection: Specifying a 90° or 45° square tube pitch provides accessible lanes for high-pressure hydro-blasting during plant maintenance. A 30° triangular pitch maximizes thermal surface density for clean process media.
3. Baffle-to-Shell Clearance Standards: Baffle plate outer diameter must conform strictly to TEMA Class R tolerances. Excessive radial clearance permits shell-side fluid bypass along the inner shell wall, reducing overall thermal transfer efficiency.

To streamline engineering procurement for global refinery, petrochemical, and pressure vessel engineering contractors, Yuhong Group offers standardized commercial execution terms:

• Minimum Order Quantity (MOQ): 1 Complete Tube Bundle Assembly or 1 Custom Heat Exchanger Tubesheet Plate.
• Incoterms & Shipping Ports: FOB Qingdao, FOB Shanghai, FOB Tianjin, or CIF / CFR destination ports worldwide.
• Fabrication Lead Time: Standard replacement cores delivered within 30 to 45 calendar days following final GA drawing approval; emergency shutdown fast-track fabrication available in 20 days.
• Third-Party Inspection (TPI): Fully compliant with BV, SGS, TÜV, Lloyd's Register, and ABS inspection procedures.

• Petroleum Refining: Crude Distillation Unit (CDU) overhead condensers, hydrotreater effluent coolers, and amine gas treating reboilers.
• Offshore Oil & Gas: FPSO top-side cooling modules, high-pressure gas compression coolers, and seawater cooling exchangers.
• Petrochemical Processing: Ethylene oxide/glycol plant heat exchangers, nitric acid coolers, and aromatics fractionating trains.