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High Pressure Oil and Gas Pipelines Carbon Steel Weld Neck Flanges custom

High Pressure Oil and Gas Pipelines Carbon Steel Weld Neck Flanges Manufacturers

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High-Integrity Carbon Steel Weld Neck Flanges

Weld Neck Flanges are considered the most reliable and structurally sound flange type for high-pressure oil and gas pipeline applications. Their long tapered hub transfers stress from the flange to the pipe wall, distributing the load and reducing stress concentrations. As a professional manufacturer, we produce carbon steel weld neck flanges to ASME B16.5 and B16.47 standards, using A105 and A350 LF2 forged materials that deliver exceptional impact toughness. The bore of our flanges is precision-bored to match the internal diameter of the mating pipe, ensuring unobstructed flow and minimizing turbulence. This seamless transition is critical in high-velocity hydrocarbon transportation where erosion and pressure drop must be kept to a minimum. Our weld neck flanges are available in all standard pressure classes from Class 150 to Class 2500, making them suitable for both surface and subsea pipeline systems across upstream, midstream, and downstream oil and gas operations.

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Weld Neck Flange Technical Specifications

ParameterSpecification Detail
Material GradeASTM A105, A350 LF2, A694 F52/F60/F65
Design StandardASME B16.5, ASME B16.47 Series A/B
Pressure ClassClass 150 to Class 2500 (ANSI)
Size Range1/2" to 60" (DN15 - DN1500)
Facing OptionsRaised Face (RF), RTJ, Flat Face (FF)
Certification3.1 MTC, NACE MR0175, API 6A compliant

Oil & Gas Pipeline Applications

Carbon steel weld neck flanges are the industry standard for high-pressure connections in upstream oil and gas gathering lines, midstream transmission pipelines, and downstream refinery piping. They are extensively used at compressor stations, metering skids, and pipeline pig launcher/receiver assemblies where pressure integrity is critical. In subsea applications, our flanges are used for riser systems and subsea manifold connections. They are also found in LNG plant feed lines and storage tank piping systems. In the petrochemical industry, weld neck flanges connect reactor vessels, heat exchangers, and distillation column nozzles. Because of their forged construction and full penetration welds, they are specified for all Class 600 and above applications. Their robust design makes them suitable for sour gas service when manufactured to NACE MR0175 requirements for sulfide stress corrosion resistance in H2S environments.

Structural & Performance Advantages

  • Superior Stress Distribution: The tapered hub gradually transfers load from the flange to the pipe, significantly reducing bending stress at the weld joint.
  • Radiographic Inspectability: Full penetration butt welds can be 100% radiographically tested, ensuring zero-defect weld integrity for critical services.
  • Minimal Flow Restriction: Bore-matched to pipe ID eliminates flow turbulence and reduces erosion in high-velocity hydrocarbon streams.
  • High Fatigue Resistance: Forged construction and generous hub radius provide excellent resistance to cyclic pressure and thermal fatigue.

Export & Project Delivery Support

We support payments via T/T and Irrevocable L/C at sight. For oil and gas projects, we maintain a large inventory of standard ANSI Class 150 to 600 flanges for immediate dispatch. All carbon steel flanges are protected with anti-rust oil and supplied with plastic pipe protectors. We use heavy-duty, moisture-sealed wooden crates suitable for sea freight to major global energy hubs. Full project documentation is provided, including 3.1 Mill Test Certificates, heat treatment charts, and dimensional inspection reports. For sour service applications, NACE compliance reports are provided as standard. Our logistics team is experienced in delivering to pipeline construction sites and offshore fabrication yards worldwide, providing real-time tracking and customs documentation support.

  • Q: What is the difference between ASME B16.5 and B16.47 weld neck flanges?
  • A: ASME B16.5 covers sizes up to 24" (NPS 24), while B16.47 covers large-diameter flanges from NPS 26 to NPS 60 in two series (A and B) with different dimensional standards.
  • Q: Can you provide flanges compliant with NACE MR0175 for sour gas service?
  • A: Yes, we supply carbon steel weld neck flanges manufactured and tested to NACE MR0175/ISO 15156 requirements for H2S sour service environments.
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Jiangyin Gaoxin Pipe Fittings Co., Ltd.
About Us
JIANGYIN GAOXIN PIPE FITTINGS CO.,LTD.
Our company is a professional manufacturer of pressure piping components. As High Pressure Oil and Gas Pipelines Carbon Steel Weld Neck Flanges Manufacturers，Our product range covers butt-weld, socket-weld, and threaded pipe fittings, including flanges and customized non-standard parts. These products are widely used in industries such as oil & gas, chemical processing, power generation, shipbuilding, papermaking, metallurgy, pharmaceuticals, and food processing. We manufacture according to standards such as ASME, EN,JIS,DIN,ANSI,GOST, MSS, GB/T,HG, DL, SH, SY,and have a complete range of inspection equipment, a strict quality control system, and various certifications（PED,AD2000,EAC, ABS,BV, DNV,NORSOK M650, ISO9001,ISO14001,ISO45001,etc.）, making us a leader in the industry.

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