Exploring Orifice Flange Types

Release time：2026-02-28    Click：12

　　Orifice flange types are specialized piping components designed to measure fluid flow accurately by creating a pressure differential across a constricted orifice plate. Mounted between two flanges in a pipeline, they are indispensable in oil and gas, chemical, and power generation industries where flow monitoring is critical. The key distinction lies in the orifice plate design—concentric, eccentric, or segmental—each tailored to specific fluid properties (e.g., solids content, viscosity). Understanding orifice flange types ensures precise measurement and operational efficiency.

　　Concentric orifice flanges are the most common type, featuring a circular orifice plate centered in the pipe. The hole diameter (0.2–0.8 times pipe diameter) creates a symmetrical pressure drop, ideal for clean liquids and gases. This design follows ISO 5167 standards, ensuring accuracy within ±1% of reading. Concentric flanges are used in water treatment plants, refineries, and HVAC systems, where homogeneous fluids flow without suspended solids. The plate is held in place by bolts, with pressure taps (flange taps or vena contracta taps) measuring upstream and downstream pressures.

　　Eccentric orifice flanges address challenges posed by fluids with suspended solids (e.g., sewage, slurry). The orifice plate is offset, with the hole tangent to the pipe bottom, preventing solids from accumulating. This design is critical in wastewater treatment and mining, where clogging would disrupt flow measurement. Eccentric flanges maintain accuracy for fluids with up to 10% solids, though they are less precise than concentric types (±2% error). The offset also allows for draining trapped solids during maintenance.

　　Segmental orifice flanges are another solution for slurries and viscous fluids. The orifice is a segment of a circle (arc-shaped), positioned at the pipe bottom to avoid solids buildup. This design is common in pulp and paper mills, where fibrous slurries flow through pipelines. Segmental plates are easier to manufacture than eccentric ones and offer similar clog resistance. However, they introduce higher turbulence, slightly reducing accuracy (±1.5% error). Some variants include a drain hole to release trapped solids.

　　Materials and construction of orifice flange types prioritize durability. Flanges are typically carbon steel (ASTM A105) or stainless steel (316), with the orifice plate made from hardened stainless steel (440C) to resist erosion. For corrosive fluids, Hastelloy or Monel plates are used. The flange face (raised face or ring-type joint) ensures a leak-proof seal with gaskets (graphite or PTFE). Pressure taps are welded to the flange, connected to differential pressure transmitters (DP transmitters) for real-time flow calculation.

　　Installation and calibration of orifice flange types require expertise. The flange pair is installed in a straight pipe section (10–50 diameters upstream, 5 diameters downstream) to ensure laminar flow. The orifice plate is aligned precisely, with bolts torqued to manufacturer specs. Calibration involves comparing measurements with a master meter (e.g., ultrasonic flowmeter) and adjusting DP transmitter settings. Regular maintenance checks for plate erosion (common in high-velocity flows) and gasket leaks. Upgrades like integrating smart transmitters (wireless, self-diagnostic) enhance reliability. Orifice flange types thus enable precise flow control in critical industrial processes.

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