China Suppliers Factory ASME B16.5 Class 150/300 Forged Steel Socket Weld Flange for High-Pressure Applications
Material Grade
Carbon Steel
ASTM A105 / A105N
ASTM A350 LF2 / LF3
ASTM A694 F42 / 46 / 56 / 60 / 65
ASTM A350 LF2 / LF3
ASTM A694 F42 / 46 / 56 / 60 / 65
Stainless Steel
ASTM A182 F304 / 304L / 304H
316 / 316L, 310S, 317, 347, 904L
ASTM A182 F51, F53, F44
316 / 316L, 310S, 317, 347, 904L
ASTM A182 F51, F53, F44
Alloy Steel
ASTM A182 F11 / 12 / 5 / 9 / 91 / 92
Sealing Face
RF
FF
FTJ
Frequently Asked Questions
Q
What is the difference between ASTM A105 and ASTM A105N material grades?
ASTM A105 is a standard specification for carbon steel forgings used in piping applications, while ASTM A105N denotes the same material that has undergone a normalizing heat treatment process. The "N" suffix indicates normalized condition, which improves mechanical properties such as toughness and uniformity of microstructure, making it suitable for more demanding pressure and temperature applications.
Q
When should I choose ASTM A350 LF2 or LF3 over standard carbon steel grades?
ASTM A350 LF2 and LF3 are low-temperature carbon steel grades specifically designed for use in cryogenic and sub-zero service conditions. They are required when the operating temperature drops below -20°F (-29°C), where standard carbon steel grades like A105 may become brittle. LF3 offers improved low-temperature impact toughness compared to LF2 and is used in even more extreme cold environments.
Q
What are the advantages of using ASTM A182 F316L stainless steel over F304L?
ASTM A182 F316L contains an addition of molybdenum (2–3%) compared to F304L, which significantly enhances its resistance to pitting and crevice corrosion, especially in chloride-rich environments such as marine, chemical processing, and offshore applications. The "L" designation in both grades indicates a low carbon content (≤0.03%), which minimizes the risk of sensitization and intergranular corrosion during welding.
Q
What does ASTM A182 F51 (Duplex Stainless Steel) offer compared to standard austenitic grades?
ASTM A182 F51 is a duplex stainless steel (UNS S31803/S32205) that combines the properties of both austenitic and ferritic microstructures. It offers approximately twice the yield strength of standard austenitic stainless steels like 304 or 316, along with excellent resistance to stress corrosion cracking (SCC) and pitting corrosion. It is widely used in oil & gas, chemical, and desalination industries where high strength and corrosion resistance are both critical.
Q
What are the applications of ASTM A182 F91 alloy steel?
ASTM A182 F91 is a chromium-molybdenum-vanadium alloy steel (9Cr-1Mo-V) designed for high-temperature, high-pressure service. It is commonly used in power generation plants, petrochemical refineries, and fossil fuel boiler systems where operating temperatures can reach up to 650°C (1200°F). Its superior creep resistance and long-term strength retention make it a preferred material for critical piping components in elevated-temperature environments.
Q
What is the difference between RF, FF, and FTJ sealing faces?
RF (Raised Face) is the most common flange face type, featuring a raised circular area around the bore that concentrates bolt load on a smaller gasket area, providing a strong seal. FF (Flat Face) has a flat sealing surface across the entire flange face and is typically used when connecting to cast iron or non-metallic equipment to avoid flange bending stresses. FTJ (Female Tongue and Groove Joint) is a precision-machined face type where one flange has a raised tongue and the other has a matching groove, ensuring accurate gasket positioning and a highly reliable, leak-proof seal — commonly used in high-pressure and critical service applications.








