Stress Corrosion Cracking Resistant F55 Super Duplex Threaded Flanges

Where tensile stresses and chloride-laden fluids co-exist, conventional austenitic stainless steel flanges can experience stress corrosion cracking (SCC). Dafugui's Stress Corrosion Cracking Resistant F55 Super Duplex Threaded Flanges feature a dual-phase ferrite-austenite structure designed to retard crack propagation. Produced in our Wenzhou manufacturing facility, these threaded flanges provide reliable mechanical joining for sour oil, gas, and power generation systems.

Resistance Mechanisms Against Stress Corrosion Cracking (SCC)

• Duplex Phase Balance: F55 super duplex steel maintains an approximate 50/50 balance of austenite and ferrite phases. The continuous ferritic matrix provides enhanced resistance to Chloride Stress Corrosion Cracking (CSCC) compared to 300-series stainless steels.

• Sour Service Suitability: Stress Corrosion Cracking Resistant F55 Super Duplex Threaded Flanges engineered in accordance with NACE MR0175 / ISO 15156 guidelines, making these components suitable for upstream oil and gas applications containing hydrogen sulfide (H₂S).

• Non-Welded Mechanical Joint: Threaded assembly avoids high residual tensile stresses associated with welding, reducing localized stress concentrations at pipe joints.

Zhejiang Dafugui S32760 Flanges Details

Zhejiang Dafugui S32760 Flanges PROCESS flow

Standards & Material Compliance

Quality Inspection Protocols

• Ferrite Content Verification: Measured via magnetic Feritscope to ensure ferrite phase balance remains within the specified 40%–60% range.

• Low-Temperature Impact Test: Charpy V-Notch impact testing performed at -40°C in accordance with ASTM A370 to verify material toughness.

• Pressure Containment Test: Stress Corrosion Cracking Resistant F55 Super Duplex Threaded Flanges will be hydrostatically tested to 1.5 times nominal rating to verify structural strength.

Factory Advantage: Heat Treatment & Metallurgical Control

• Precision Solution Annealing: Solution heat treatment and rapid water quenching processes are strictly controlled to prevent deleterious phase precipitation (σ-phase).

• Certified Testing Equipment: In-house metallurgical and mechanical testing labs ensure product compliance before release.

Commercial & Procurement Information

• MOQ: 1 Piece

• Standard Delivery Lead Time: 15–30 Days

• Warranty: 12 Months limited quality warranty from shipment date

• Export Packaging: Protective end caps, moisture-proof wrapping, packed in fumigated ISPM 15 wooden crates

Frequently Asked Questions

• How does the dual-phase structure of F55 resist stress corrosion cracking?
The ferritic phase in the duplex matrix acts as a barrier, helping to block micro-crack propagation induced by tensile stress and chloride exposure.

• What is the low-temperature design limit for Stress Corrosion Cracking Resistant F55 Super Duplex Threaded Flanges?
Forged UNS S32760 retains impact toughness down to -50°C, making it suitable for cold-climate and subsea installations.

• Is ferrite content documented on the Material Test Certificate?
Yes. Every heat lot includes measured ferrite percentage data on the EN 10204 3.1 certificate.