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Industrial Weld Neck Flange for Oil and Gas Pipeline Connection - China Suppliers and Factory Direct Quality
Material Grade
Carbon Steel
ASTM A105 / A105N, 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
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 for carbon steel flanges?
ASTM A105 refers to standard carbon steel forgings for piping components, while ASTM A105N indicates the same material that has undergone normalizing heat treatment. The "N" suffix denotes normalized condition, which improves toughness and mechanical properties, making A105N suitable for more demanding applications.
Q
What are the main differences between 304L and 316L stainless steel flanges?
Both 304L and 316L are low-carbon austenitic stainless steels. The key difference is that 316L contains molybdenum (2–3%), which significantly enhances its resistance to chloride corrosion and pitting. 316L is therefore preferred in marine, chemical, and highly corrosive environments, while 304L is widely used in general-purpose applications.
Q
What does ASTM A182 F51 refer to, and where is it commonly used?
ASTM A182 F51 refers to duplex stainless steel (UNS S31803 / S32205). It offers a combination of high strength and excellent corrosion resistance, particularly against stress corrosion cracking and pitting. It is commonly used in oil & gas, chemical processing, desalination, and offshore industries.
Q
What is the difference between RF, FF, and FTJ sealing faces?
RF (Raised Face) is the most common flange facing, where the sealing area is raised above the bolt circle. FF (Flat Face) has the entire flange face in the same plane and is used when mating with flat-face flanges to prevent bending stress. FTJ (Full-Face with Tongue and Groove) provides a more secure seal, used in high-pressure or critical sealing applications.
Q
When should alloy steel grades such as ASTM A182 F91 or F92 be selected?
ASTM A182 F91 and F92 are chrome-molybdenum alloy steels designed for high-temperature and high-pressure service. F91 (9Cr-1Mo-V) and F92 (9Cr-2W) are typically used in power generation, steam pipelines, and petrochemical plants where operating temperatures can exceed 600°C. They offer superior creep resistance compared to standard carbon or low-alloy steels.
Q
Why is 904L stainless steel used in special applications?
904L is a high-alloy austenitic stainless steel with low carbon content and high additions of nickel, chromium, molybdenum, and copper. This composition gives it exceptional resistance to strong acids (including sulfuric acid), chloride-induced corrosion, and stress corrosion cracking. It is commonly specified for chemical processing, acid handling, and highly corrosive industrial environments where standard grades like 316L would be insufficient.