S31803 Dual Phase Steel Flange Round Steel Flange 1/2in To 120in

Product Specification

S31803 Dual-phase Steel Flanges in Various Industries with Material for Secure Connections

Crafted from S31803 duplex stainless steel (UNS S31803), these high-performance flanges combine exceptional mechanical strength and outstanding resistance to chloride-induced corrosion, making them the ideal choice for oil & gas pipelines, chemical processing, desalination plants, and offshore platforms. With a dual-phase microstructure (50% austenite + 50% ferrite), S31803 delivers 2x the yield strength of standard 316L steel and superior resistance to stress corrosion cracking (SCC), pitting, and crevice corrosion in harsh environments.

Key Advantages

✅ Unmatched Corrosion Resistance:

• PREN ≥35 ensures robust performance in chloride-rich media (seawater, brine, H₂S-containing fluids) and acidic/alkaline environments (pH 2-12).

• Ideal for subsea umbilicals, heat exchangers, and coastal chemical plants exposed to salt spray.

✅ High Strength & Durability:

• Tensile strength ≥620 MPa and excellent impact toughness for high-pressure (up to PN100/Class 2500) and high-vibration applications.

• Resists erosion and abrasion in slurry transport, mining, and pulp & paper industries.

✅ Cost-Efficient Longevity:

• Outperforms 316L and 904L steels in aggressive conditions, reducing maintenance and replacement costs.

• Suitable for temperatures ranging from -50°C to 250°C (-58°F to 482°F).

✅ Global Compliance & Traceability:

• Manufactured to ASTM A182, ASME B16.5, EN 1092-1, and NACE MR0175/ISO 15156 standards for sour service environments.

• Full material traceability (MTC 3.1) and ISO 9001/14001 certifications ensure quality and sustainability.

✅ Customizable Solutions:

• Types: Weld neck, slip-on, blind, threaded, and socket weld designs.

• Sizes: DN15 to DN2000, with customizable bore dimensions, face finishes (RF/RTJ/FF), and pressure ratings.

• Post-Treatment: Solution annealing, pickling, or shot blasting for enhanced surface integrity.

Industry Applications

• Oil & Gas: Subsea pipelines, LNG terminals, and refinery acid recovery systems.

• Chemical Processing: Reactor vessels, sulfuric acid coolers, and fertilizer production.

• Water Treatment: Seawater reverse osmosis (SWRO) plants, brine pumps, and offshore desalination units.

• Pulp & Paper: Bleaching equipment, digesters, and corrosive chemical storage.

Why Choose S31803 Flanges?

• Leak-Proof Reliability: Precision-machined sealing surfaces ensure zero-leak performance in critical systems.
• Rapid Delivery: Stock availability for common sizes (DN15-DN600) with 15-day lead time for urgent orders.
•  Technical Support: Free corrosion compatibility analysis, welding guidelines, and installation support.

Quality Inspection

Quality Management Department is establshed in the enterprise, which is responsible for the implementation of quallty management acrossall sectors, including QC, QA and implement and supervise various management system. The company reviews the Quality Manual byconducting management reviews annually to confirm its conformance, effectiveness and suitability.

Project Achievement

HENGLI Petrochemical 40 million / year ton of oil refining integration project	ZHEJIANG Petrochemical 40 million / year ton of oil refining integration project	LIANYUNGANG Petrochemical 3.2 million tons / young hydrocarbon comprehensive	YISHENG New Material The 6.6 million tons / year of the PTA project	CNOOC Huizhou Refining & Chemical Co Huilian Phase II, 22 million / year ton of oil refining Reconstruction and expansion project	Sinopec Zhenhai Refining & Chemical Company 1.2 million / year ton ethylene renovation and expansion project	Wanhua Chemical 480,000 tons / year bisphenol A integration project	GUANGXI Huayi New Materials Integration project of new chemical materials	CNOOC Shell The SMPO & POD project	China AtlantoShaanxi Coal Chemical Industry: 1.8 million tons / year ethylene glycol project
Hainan Huasheng 2.26 million tons / year non-photogamic polycarbonate project	Shenghong Refining The 16 million tons / year oil refining project	Anhui Haoyuan Chemical Industry 300,000 tons / year ethylene glycol project	Heilongjiang Longyou Petrochemical Company5.5 million tons / year heavy oil catalytic pyrolysis project	HuaLu Hengsheng 500,000 tons / year ethylene glycol project	Baofeng Energy600,000 tons / year methanol to olefin project	Jiangnan Shipyard (98000m³ liquefied ethane ship, etc.) Brand number: 316 / 316L, delivery time: 2020.12	Keppel shipyard in Singapore (FLNG ship) Brand number: 316 / 316L, delivery time: 2020.1	Guangzhou Wenchong Shipyard (Super double-phase steel desulfurization tower) Brand number: S32750 Delivery time: 2021.3	CSSC Dalian (FPSO, MV31, etc.) Brand number: 316L, etc., delivery date, 2019.8
725 Institute of China Shipbuilding Industry (Cu-Ni alloy Tube)	Nantong COCSO Shipyard (FSRU ship module)	CIMC Raffles (Drilling Rig)	CNOOC Orient 13-2 (Lined pipe)	CNOOC Bozhong 19-6 (Lined Pipe)	Petrobras MODEC FPSO (COSCO Shipping)	CNOOC Guangxi LNG, storage and transportation storage Brand number: 304 / 304L Specification: (8 "~32")×(3.76~9.53mm)	CNOOC Zhejiang LNG Phase II Brand number: 304 / 304L Specification: (6 "~28")×(7.11~10.31mm)	Sinopec Shandong LNG Phase II Brand number: 304 / 304L Specification: DN250 SCH10S	LIANYUNGANG Petrochemical A 4X160000m³ low-temperature ethane storage tank Brand number: 304 / 304L Specification: 813X12.7MM Delivery time: 2020.9
Sinopec Luoyang Institute Wenzhou LNG terminal Brand number: 304 / 304L Specification: 219.1~711X12.7MM Delivery time: 2022.3	Huatai Shengfu 160,000 m ³ low-temperature ethane storage tank Brand number: 304 / 304L Specification: 219~508X9.53MM	YAMAL LNG Brand number: 304 / 304L Specification: 406~914X9.53MM	Beijing Maiden Voyage	Oriental Hope	Sichuan Yongxiang 70,000 tons / year high purity polysilicon project	Xinjiang Daquan 25,000 tons / year high purity polysilicon project	Eagle Central China Paper Industry 500,000 tons of box board project	Guangxi Sun Paper 3.5 million tons of forest pulp and paper integration project	APP for Asian pulp and paper Chemical machine pulp and sewage treatment project
TCL Shenzhen Huaxing Optoelectronics semiconductor clean pipeline project	Beijing Daxing Airport	Hong Kong-Zhuhai-Macau/Macao Bridge Tubes used for stainless steel construction	CNNC Xiapu nuclear Power Plant Fast reactor demonstration project of CNNC 2.3	CONBA Stainless steel pipe for pharmaceutical engineering	Shenghong Refining Stainless steel associated heat pipe	Hangzhou Sewage Treatment Plant Stainless steel pipe for backwash purification unit	Qilu Pharmaceutical Fluid stainless steel pipe for raw material delivery	Zijin Mining Wet copper smelting, stainless steel sewage pipe	ect
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Certificate

API-5LD AUTHENTICATION	American Petroleum Institute API 5LC Certificate	ASME Certificate in the United States	EU PED&AD2000 certificate	ABS classification society certification certificate in the United States	DNV Det Norske Veritas Certificate	RINA Italian Bureau of Shipping Certificate	BV French Bureau of Shipping certification	LR Lloyd's Register Certificate of Approval	Customs Union EAC Certificate	Russian GOST certificate

Raw Material Vendors	Cooperation Partners

Packing and Shipping:

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Upgrade to S31803 Duplex Steel Flanges – Where Strength Meets Corrosion Resistance!