Slip-On (SO) flange Class 900 ASME 16.5 is a critical component in high-pressure piping systems. Unlike weld-neck flanges, slip-on flanges feature a simple structure where the pipe slips through the flange bore, allowing for easy alignment and installation. This design combined with the Class900 pressure rating that can balances usability and performance.
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Key Dimensional Specifications of ASME B16.5 SO Flange Class900
Bore Size
The bore diameter of SO flange Class900 matches the nominal pipe size (NPS) of the connected pipe, ranging from NPS 1/2 to NPS 24 (per ASME B16.5's standard scope). For example, an NPS 2 SO flange Class900 has a bore diameter of 2.375 inches (for schedule 40 pipe), ensuring a snug fit with the pipe outer diameter.
Flange Thickness & Diameter
Class900 SO flanges have a thicker hub and larger overall diameter compared to lower-class slip-on flanges to accommodate high-pressure loads. For NPS 4, the flange thickness (web thickness) is 1.125 inches, and the outside diameter is 10.75 inches. These dimensions increase proportionally with NPS to maintain structural stability.
Bolt Circle & Bolt Specifications
The bolt circle diameter (BCD) and number of bolts are critical for distributing pressure evenly across the flange face. For NPS 3 Class900 SO flange, the BCD is 8.5 inches, with 8 bolts of size 1-1/8 inches. ASME B16.5 specifies bolt materials (e.g., A193 B7) to ensure compatibility with the flange's pressure-temperature rating.
Applications of SO Flange Class900 ASME B16.5
Petroleum & Gas: Upstream oil exploration (wellheads), midstream pipeline transmission, and downstream refineries (hydrocracking, distillation units).
Chemical Processing: Corrosive chemical transfer (acids, bases), polymer production, and pharmaceutical manufacturing (high-purity systems).
Power Generation: Fossil fuel power plants (boiler feedwater lines, steam turbines) and nuclear power plants (secondary coolant systems).
Marine & Offshore: Offshore oil platforms, shipboard piping systems, and subsea pipeline connections (with corrosion-resistant materials).
FAQ
A: Can SO Flange Class900 ASME B16.5 be used for high-temperature applications?
Q: Yes, but the maximum operating temperature depends on the material. Carbon steel (A105) Class900 SO flanges can be used up to 800°F, while stainless steel (316L) can withstand up to 1500°F.
A: What is the difference between ASME B16.5 and ASME B16.47 for Class900 SO flanges?
Q: ASME B16.5 covers flanges up to NPS 24, while ASME B16.47 (Series A/B) covers larger flanges (NPS 26 to NPS 60). SO Flange Class900 is only specified in ASME B16.5 for NPS ≤24.
A: Can Class 900 Slip-On (SO) flanges and Class 900 Plate (PL) flanges be interchanged?
Q: No. They differ in structure (SO flanges have a short neck, while PL flanges do not) and load-bearing capacity. There are differences in the sealing surface and bolt stress, and interchanging them can easily lead to sealing failure or insufficient strength.
A: Do Class 900 SO flanges require regular maintenance under long-term high-pressure conditions? What is the maintenance cycle?
Q: Yes. Core maintenance includes: sealing surface inspection, bolt tightening inspection, and gasket aging inspection. The maintenance cycle is: generally 1-2 years for normal operating conditions; 6-12 months for high-temperature/high-pressure/highly corrosive conditions; and immediate inspection in case of abnormal situations.
ASME B16.5 SO Flange Class900 Dimension
