Welding Necked Flange Steel Forged RF

Gnee Steel (Tianjin) Co., Ltd. is one of the most professional manufacturers and suppliers of welding necked flange steel forged rf in China. With abundant experience, we warmly welcome you to wholesale customized welding necked flange steel forged rf from our factory. For price consultation, contact us.

The Cr composition of Inconel 690 nickel-based alloy is high, about 30%, and Cr can prevent the precipitation of grain boundary carbonites, so as to avoid chromium deficiency near the grain boundary, which can improve the antioxidant ability. Inconel 690 alloy has a high Ni content of approximately 60%, which is resistant to stress corrosion cracking in sodium hydroxide solutions and chloride environments.

FAQ

Q1: What is a Weld Neck (WN) flange? How does it differ from a Slip-On (SO) flange?
WN flanges are joined to the pipe via a long tapered hub using a full-penetration butt weld; stress is transferred gradually along the taper, resulting in a fatigue life approximately three times that of SO flanges. They are suitable for Class 600 and higher ratings and cyclic loading conditions.

Q2: What is the standard height of an RF (Raised Face) sealing surface?
For Class 150–300, the raised face height is 1/16″ (1.6 mm); for Class 400–2500, it is 1/4″ (6.4 mm). The surface is typically machined with a spiral serrated finish to improve gasket seating.

Q3: What materials are commonly used for forged steel WN RF flanges?
ASTM A105 carbon steel is the most common; A182 F11/F22 is selected for high-temperature steam, LF2/LF3 for low-temperature service, F304/F316 for corrosive environments, and F91 for ultra-supercritical applications.

Q4: What size and pressure class ranges does ASME B16.5 cover?
B16.5 covers NPS ½″–24″ (DN15–DN600) and pressure classes 150, 300, 400, 600, 900, 1500, and 2500; larger sizes require reference to ASME B16.47.

Q5: What is the pressure rating of an A105 flange at 200°F?
At 200°F, the MAWP is 1,360 psi for Class 600, 2,035 psi for Class 900, and 3,395 psi for Class 1500; ratings decrease as the temperature rises.

Q6: What is the manufacturing process flow for forged WN RF flanges?

Billet heating to 2,000–2,200°F → Open-die forging/ring rolling → Normalizing + Tempering → CNC rough & finish machining (including RF serrations) → NDT inspection → Oiling/Galvanizing → Packaging & marking.

Q7: What NDT methods are included in the factory inspection?
100% RT (E94) or UT (E165) for Class 900 and above; 100% PT (E709) for weld zones; OES chemical analysis, tensile testing, and hardness testing per heat; EN 10204 3.1 MTC provided for exports.

Q8: Are B16.5 and B16.47 flanges interchangeable?
They are not interchangeable. They differ in bolt circle diameter, flange outer diameter, and sealing face geometry; the same standard must be used at both ends of a pipeline section to ensure proper alignment and assembly.

Q9: In which industries are forged WN RF flanges primarily used?
Oil and gas wellheads and gathering pipelines; refining and chemical reaction units; power plant main steam and reheat steam lines; LNG cryogenic transport; offshore platform process piping; and pipelines handling corrosive chemical media.

Q10: What are the HS code for export customs declaration and the packaging requirements?
HS Code: 7307.11; Packaging: VCI anti-rust film + wooden pallets/crates; sealing faces protected with covers or plastic film; documentation included: MTC, CoC, NDT reports, and packing list.

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