High Corrosion Resistance Weld Neck Flange with Full Penetration Butt Welds for Class 150 to Class 2500 Pressure

Weld Neck Flange features a long tapered hub smoothly transitioning to the pipe wall. It is connected to pipes via full penetration butt welds. The tapered hub disperses stress concentration at the weld joint, delivering superior fatigue resistance, structural strength and sealing reliability. It is the preferred flange for critical piping systems.

• ✅ High temperature & high pressure piping
• ✅ Cryogenic / low temperature service (LNG, liquid nitrogen)
• ✅ Frequent thermal cycling, vibration and alternating fatigue load
• ✅ Sour gas, corrosive medium, hazardous fluid transportation
• ✅ Systems requiring strict anti-leakage performance

1. Oil & Gas Industry Offshore platforms, onshore refineries, crude oil & natural gas transmission pipelines, wellhead piping, sour gas service (compliant with NACE MR0175).
2. Petrochemical & Chemical Plants Reactor piping, high-pressure synthesis loops, acid & alkali medium pipelines, hydrogen process piping.
3. Power Generation Thermal power, ultra-supercritical units, main steam pipeline, high-pressure feedwater systems, waste heat recovery piping.
4. LNG & Cryogenic Engineering LNG receiving stations, cryogenic storage and transport pipelines, liquid gas low-temperature piping.
5. Marine & Shipbuilding Offshore vessel process piping, saltwater corrosion-resistant onboard pipeline systems.
6. Pharmaceutical & New Energy High-purity process pipelines, hydrogen energy transmission systems, battery chemical production lines.
7. Water Treatment & Heavy Industry Large-scale industrial desalination, high-pressure circulating water systems, metallurgical high-temperature medium pipelines.

1. ASME B16.5 Pipe Flanges and Flanged Fittings (NPS 1/2" ~ NPS 24"; Class 150 ~ 2500)
2. ASME B16.47 Large Diameter Steel Flanges (NPS 26" ~ NPS 60; Series A / Series B)
3. EN 1092-1 Steel flanges for piping systems (PN6 ~ PN400, European metric system)
4. JIS B2220 Japanese standard steel pipe flanges
5. GB/T 9115, HG/T 20592, HG/T 20615 Chinese industrial standards

• ASTM A105: Carbon steel flanges for ambient & higher temperature service
• ASTM A350 LF2: Low-temperature carbon steel flanges
• ASTM A182 F304/F316L/F51/F53: Stainless steel, duplex & super duplex steel flanges

• ASME B31.3 Process Piping Code (specifies WN flange mandatory for severe cyclic & hydrogen service)
• ASME B31.1 Power Piping Code

RF (Raised Face), FF (Flat Face), RTJ (Ring Type Joint), MFM (Male & Female Face)