デュプレックススチールフランジとは何ですか

Duplex steel flanges are piping components made from duplex stainless steel, a family of stainless steels that contain a balanced mix of austenitic and ferritic phases. This dual-phase structure gives duplex steel superior mechanical strength, 優れた耐食性, and high resistance to stress corrosion cracking.

These flanges are used in a variety of critical applications, including offshore oil rigs, 淡水化プラント, chemical processing units, 海洋構造物. The combination of strength and corrosion resistance makes duplex steel flanges an ideal choice for demanding environments where conventional stainless steels may fail.

Chemical Composition and Grades

Duplex stainless steels generally contain:

クロム: 21 に 25 パーセント
ニッケル: 4.5 に 7 パーセント
モリブデン: まで 3.5 パーセント
Nitrogen: added to enhance pitting resistance
Low carbon content to minimize carbide precipitation

Common grades used for duplex steel flanges include:

UNS S31803 / S32205 (としても知られています 2205 二重)
UNS S32750 (スーパーデュプレックス)
UNS S32760
UNS S32550

Each grade is selected based on the specific mechanical and environmental requirements of the application.

Advantages of Duplex Steel Flanges

Duplex steel flanges offer a wide range of benefits compared to traditional stainless or carbon steel flanges:

1. 高強度

Duplex steel has nearly twice the yield strength of standard austenitic stainless steel, allowing for thinner sections and reduced weight without compromising strength.

2. 耐食性

They provide excellent resistance to general corrosion, 穴あき, 隙間腐食, and especially to chloride-induced stress corrosion cracking.

3. コスト効率

Despite higher initial material costs, the long service life and reduced maintenance needs make duplex flanges more cost-effective over time.

4. Superior Toughness

The austenitic component enhances toughness even at sub-zero temperatures, making these flanges suitable for arctic or deep-sea conditions.

5. Resistance to Erosion

Duplex alloys resist erosion from fast-flowing seawater or corrosive fluids, making them ideal for high-pressure applications.

Common Types of Duplex Steel Flanges

sasaflange manufactures a full range of duplex steel flanges according to international standards such as ASME, ASTM, EN, およびDIN. Some of the most common types include:

ウェルドネックフランジ – Ideal for high-pressure applications
スリップオンフランジ – Easier installation in low-pressure systems
ソケットウェルドフランジ – Excellent for small diameter high-pressure pipes
ブラインドフランジ – Used to terminate or isolate pipe sections
重ね継手フランジ – Allow for quick bolt alignment in systems
ねじれたフランジ – Used for non-welded connections
オリフィスフランジ – Used with flow meters and instrumentation

All flanges produced by sasaflange are available in a variety of face types, 顔の盛り上がりなど (RF), リング型ジョイント (RTJ), and flat face (FF).

Applications of Duplex Steel Flanges

Thanks to their exceptional properties, duplex flanges are widely used in:

1. 石油およびガス産業

Duplex flanges are preferred for offshore platforms, subsea equipment, and transport pipelines due to their strength and resistance to seawater corrosion.

2. 海水淡水化プラント

The high chloride resistance makes them ideal for saltwater processing and brine management.

3. 化学および石油化学処理

Duplex steel can handle aggressive media and temperature variations common in reactors and storage tanks.

4. 海洋産業

Used in shipbuilding, underwater pipelines, and marine structures for their resistance to erosion and corrosion.

5. 発電

From nuclear plants to renewable energy systems, duplex flanges are used in high-pressure steam and fluid systems.

規格と認証

sasaflange ensures all duplex steel flanges meet or exceed the following international standards:

ASTM A182 / A240
ASME B16.5 / B16.47
EN 1092-1
NORSOK M-630 / M-650
ISO 15156 (for sour service)

Each flange is also traceable by heat number, ensuring complete transparency and accountability throughout the supply chain.

Duplex vs Super Duplex Flanges

While both duplex and super duplex flanges offer superior performance, super duplex contains higher levels of chromium and molybdenum, offering better corrosion resistance and mechanical properties. Super duplex flanges are generally used in even more extreme environments such as:

Deepwater oil drilling
High salinity applications
Aggressive chemical environments

sasaflange provides both duplex and super duplex flange solutions tailored to specific industrial needs.

Welding and Machining Considerations

Welding duplex steel flanges requires expertise and control over heat input to maintain the phase balance. Poor welding can lead to loss of corrosion resistance and mechanical integrity.

Machining duplex steel is more challenging than austenitic stainless steel due to its higher strength. Proper tooling and coolant techniques must be used to ensure precision and tool longevity.

sasaflange works with experienced welders and machinists to ensure all flanges are fabricated to exact specifications without compromising structural integrity.

Surface Finish and Protection

アプリケーションに応じて, sasaflange offers several surface finishes for duplex flanges:

Pickled and passivated for restoring corrosion resistance
Machined or polished surfaces for smooth flow and sealing
Coated surfaces (where needed) for enhanced protection

Special attention is paid to surface cleanliness, especially for industries like food, 製薬, and desalination.

Quality Control and Testing

Every duplex steel flange from sasaflange undergoes rigorous quality control, 含む:

Visual and dimensional inspection
Ultrasonic testing (ユタ州)
染料浸透試験 (PT)
静水圧試験
確実な物質識別 (PMI)
第三者による検査 (as requested)

All test results are documented in Mill Test Certificates (MTC) and comply with EN 10204 タイプ 3.1 または 3.2.

Packaging and Delivery

To prevent contamination and damage during shipping, sasaflange packs each duplex steel flange with:

Plastic caps to protect sealing faces
Anti-corrosion paper wrapping
Plywood boxes or crates for export
Clear labeling with product information and heat numbers

Global delivery is available with full documentation support, including certificates of origin, material test reports, and shipping invoices.

最終的な考え

Duplex steel flanges are a smart investment for industries demanding high performance, 耐久性, 耐食性. Their ability to perform under pressure in extreme environments makes them one of the most reliable flange materials available today.

Whether you are sourcing for offshore drilling, 化学処理, or marine systems, ササフランジ provides high-quality duplex flange solutions engineered to meet your specifications and exceed expectations.