Overview
Double Welding Neck Flanges are specialized pipe connectors with two integrated neck sections for welding to adjacent pipes or equipment. Unlike standard welding neck flanges, this design provides dual reinforcement points, making them ideal for critical high-pressure systems where joint integrity is paramount. Manufactured to international standards like ASME B16.5, ANSI B16.47, and ISO 7005, these flanges are available in pressure classes ranging from 150 to 2500. The extended hub design gradually distributes stress away from the welded joint, significantly reducing fatigue failure risks in dynamic piping systems.
Structure and Working Principle
The flange consists of three main components: the welding neck sections (typically with 37° bevel ends for V-groove welding), the central flange ring with bolt holes, and the sealing face (commonly RF or RTJ). The double-neck configuration allows for bidirectional pipe connections without requiring separate spool pieces. During operation, the welded joints create permanent, full-penetration connections that match the pipe's strength. The flange's thickness and hub length increase proportionally with pressure class to maintain structural stability. Gaskets installed between mating flanges compress under bolt torque to form pressure-resistant seals.
Key Features
1. Enhanced Pressure Containment: The dual-neck design withstands up to 25% higher burst pressures compared to single-neck equivalents in Class 600+ applications. 2. Vibration Resistance: The extended hubs act as dampers, reducing vibration transmission in compressor and pump discharge lines. This is particularly valuable in offshore platforms and reciprocating machinery installations. 3. Metallurgical Continuity: Proper welding creates homogeneous metal structures across joints, crucial for cryogenic services where thermal contraction could fracture weaker connections.
Application Areas
Primary installations include: - Offshore oil & gas production manifolds - High-pressure steam lines in power plants (up to 1000°C) - Reactor feed systems in chemical processing - Hydraulic fracturing (fracking) equipment These flanges are specified in API 6A wellhead equipment and ASME B31.3 process piping where cyclic loading occurs. The double-neck design is mandatory in some European pressure equipment directives (PED) for certain hazardous fluid services.
Maintenance and Precautions
Regular inspections should check for: 1. Weld toe cracks (use MPI or UT testing) 2. Bolt load relaxation (re-torque after initial heat cycles) 3. Creep deformation in high-temperature service Critical installation practices include: - Maintaining 1.5-3mm root gap during welding - Post-weld heat treatment for carbon steel over 19mm thickness - Using alignment pins during assembly to prevent flange face damage Avoid water quenching after welding to prevent hydrogen-induced cracking, especially in sour gas service.
B2B Procurement Guide
Technical specifications should include: 1. Material grade with impact test requirements (e.g., ASTM A350 LF2 Charpy tested) 2. NDE requirements (RT, UT, or PT examination levels) 3. Dimensional tolerances per MSS SP-44 Leading manufacturers include: - Flanschenwerk Bebitz GmbH (Germany) - Metal Udyog (India) - Pacific Hoseflex (USA) Bulk purchase discounts typically apply for orders exceeding 50 units. Lead times range from 4-12 weeks for custom materials like duplex stainless steel. Always request mill test certificates (MTCs) and material traceability documentation.
Related Manufacturers
- 主营：弯头、三通管件、钢制弯头、喷塑法兰、不锈钢法兰、大口径法兰盘、法兰管件、管道连接件、不锈钢异径管、涂塑管件
- 主营：异形弯、异径管、大三通、法兰管、法兰盘、法兰片、弯头法兰、双盘弯头、热卷法兰、厚壁管、化工管、斜三通、石化管、高压管、焊接管、异形管、折流板、碳钢管、三通河、船标管、变径管、连接防漏、管线钢弯、加高管帽、异径三通
- 主营：弯头、管件、三通、法兰、不锈钢法兰、四通、大小头、盲板、管板、人孔、封头、管帽、管托、支吊架、不锈钢管件、绝缘接头、补偿器、防水套管、耐磨管件、疏水节、固定节、不锈钢弯头、不锈钢三通、不锈钢大小头、订制管件
- 主营：抗硫弯头、无缝弯头、螺纹三通、法兰盲板、抗硫法兰、wn对焊法兰、硫对焊法兰、锻造高压法兰、硫异径管、无缝弯管、过球三通
- 主营：过滤器
- 主营：钢制伸缩器、可曲挠橡胶接头、鸭嘴阀、双法兰伸缩接头、单法兰伸缩接头、补偿器、伸缩节、伸缩器、软接头、防水套管、柔性套管、橡胶接头、橡胶软接头、止回阀、刚性防水套管、铸铁伸缩器、套筒补偿器、套管伸缩器、轴向外压补偿器、不锈钢波纹补偿器、橡胶弯头、偏心异径橡胶接头、丝扣橡胶接头
- 主营：SCH80活套法兰、南亚PVC管、积水clean PVC管
- 主营：涂塑钢管、防腐钢管、保温钢管、双环氧涂塑钢管、涂塑复合钢管、钢塑复合管、内外涂塑钢管、农田灌溉钢管、热浸塑穿线管、刷油缠布防腐钢管、聚氨酯保温钢管、喷涂缠绕保温钢管、IPN8710钢管、钢套钢蒸汽保温钢管、镀锌铁皮保温钢管、聚丙烯防腐钢管、螺旋防腐钢管、焊接防腐钢管、3PE防腐钢管、TPEP防腐钢管、聚乙烯防腐钢管、环氧粉末涂塑钢管、环氧树脂防腐钢管、环氧煤沥青防腐钢管、水泥砂浆防腐钢管
- 主营：壁胶管、吸胶管、砂浆管、矿用胶管、疏浚胶管、通风胶管、吸砂胶管、输送胶管、输气胶管、输送软管、蒸汽胶管、船用胶管、卸灰胶管、接头胶管、耐磨胶管、工业胶管、市政排污、液压支架、绝缘橡胶、喷砂胶管、低压胶管、柔性软管、空气胶管、夹布胶管、复合软管
- 主营：法兰、弯头
- 主营：工业管
- 主营：弯头、三通、异径管、法兰、大小头、人孔、封头、支吊架、管托、沟槽管件、防水套管、补偿器、高压承插管件、橡胶软接头、防腐钢管、保温钢管、镀锌钢管、方管
- 主营：破碎机配件、烧结机耐热配件、焚烧炉炉排、双金属耐磨管道、双金属耐磨弯头、定制双金属异形管件、变径管、复合耐磨管、耐热铸钢件、隔热垫、陶瓷复合耐磨管道、烧结机炉条、耐磨铸件、高铬铸铁炉条、高锰钢耐磨锤头、高锰钢耐磨衬板、高铬铸铁耐磨衬板、稀土合金耐磨管道、定做炉排、化学成分、锅炉配件、耐热钢炉排、粉碎设备配件、出口耐热钢铸件、出口炉排
- 主营：HIC低硫磷管件、NACEMR0175标准、大口径对焊弯头、API6A6B法兰、紧凑型法兰、NOROK挪威标准法兰、锚固法兰、双相钢弯头、合金管件
- 主营：双金属弯头采购、消防喷淋装置