Orifice Flanges: Complete Guide to Flow Measurement in Industrial Piping
Introduction
Orifice flanges are specialized pipe flanges designed for precise flow measurement in industrial piping systems. These critical components work in conjunction with orifice plates to create differential pressure measurements.
What Are Orifice Flanges?
Definition and Purpose
Orifice flanges are paired flanges with precisely machined slots or holes that accommodate an orifice plate, generating a pressure differential that correlates to flow rate.
Key Components:
- Orifice Flange Pair – Two matching flanges
- Orifice Plate – Precision-machined restriction element
- Pressure Tappings – Connection points for instrumentation
- Gaskets – Seal the orifice plate assembly
Orifice Flange Design Features
Pressure Tapping Locations:
| Tapping Type | Location | Application |
|---|---|---|
| Flange Taps | 1 inch from orifice plate | Most common, standard |
| D and D/2 Taps | 1D upstream, 0.5D downstream | High accuracy |
| Corner Taps | At orifice plate faces | Small pipe sizes |
Orifice Plate Bore Configurations:
- Concentric Bore – Standard for clean fluids
- Eccentric Bore – For liquids with gas or solids
- Segmental Bore – For dirty services
- Quadrant Edge – Low flow rate applications
ASME Standards and Specifications
Primary Standards:
- ASME B16.36 – Orifice Flanges and Orifice Flange Unions
- ASME MFC-3M – Measurement of Fluid Flow in Closed Conduits
- ISO 5167 – Measurement of Fluid Flow by Pressure Differential Devices
Installation Requirements
Straight Run Specifications:
- Minimum: 10-20 pipe diameters upstream, 5 downstream
- Recommended: 20-40 pipe diameters upstream, 10 downstream
- Ideal: 50+ pipe diameters upstream, 15 downstream
Common Applications
Industry Applications:
- Oil and Gas: Crude oil flow measurement, natural gas custody transfer
- Chemical Processing: Raw material feed rates, product flow monitoring
- Power Generation: Feedwater flow, steam flow measurement
- Water and Wastewater: Raw water intake, treated water distribution
Conclusion
Orifice flanges remain the most widely used flow measurement technology in industrial applications due to their simplicity, reliability, and standardization.
Songhai Flanges manufactures ASME B16.36 compliant orifice flanges in all pressure classes and materials.
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