In differential pressure flow measurement systems, the orifice plate plays a crucial role in creating restriction within a pipeline. However, the accuracy of the measurement depends not only on the plate itself but also on how and where pressure is tapped.
This is where orifice tapping becomes critical. The placement of pressure taps directly affects differential pressure readings and, ultimately, the calculated flow rate.
Let’s quickly explore orifice tapping types, orifice plate tapping locations, and the differences between orifice flange tapping and other methods.
What is Orifice Tapping?
Orifice tapping refers to the method of taking pressure measurements upstream and downstream of an orifice plate to determine the differential pressure.
When fluid passes through an orifice plate:
- • Velocity increases
- • Pressure decreases
- • A pressure difference is created
Pressure taps installed at specific locations measure this difference, which is used to calculate flow rate.
High-quality measurement systems rely on precision-engineered orifice plate flow meter components to ensure accuracy and repeatability.
Why Orifice Plate Tapping Is Important
Incorrect tap placement can result in:
- • Inaccurate pressure readings
- • Flow calculation errors
- • Energy losses
- • Operational inefficiencies
Proper orifice plate tapping locations ensure that:
- • Pressure is measured at standardised points
- • Readings are consistent
- • Flow rate calculations are reliable
Common Orifice Tapping Types
There are several standardized orifice tapping types used in industrial applications.
1. Flange Tapping
Orifice flange tapping is one of the most common methods.
In this system:
- • Pressure taps are drilled directly into the flanges holding the orifice plate.
- • Taps are located 1 inch (25.4 mm) upstream and downstream from the plate.
It is widely used because:
- • Installation is simple
- • Compact design
- • Suitable for smaller pipe diameters
This method is often referred to as flange tap orifice configuration.
2. Corner Tapping
In corner tapping:
- • Pressure taps are located immediately at the upstream and downstream faces of the plate.
- • Commonly used in smaller diameter pipelines.
It provides accurate results when precise installation standards are followed.
3. Radius Tapping (D and D/2 Tapping)
In radius tapping:
- • Upstream tap is placed one pipe diameter (D) upstream.
- • Downstream tap is placed half a diameter (D/2) downstream.
This method is often used in research and experimental setups.
4. Pipe Tapping
Pipe tapping involves:
- • Upstream tap at 2.5 pipe diameters (2.5D)
- • Downstream tap at 8 pipe diameters (8D)
It is less common in modern systems due to larger space requirements.
Flange Tapping Orifice Plate Explained
The flange tapping orifice plate setup integrates taps directly into the flange assembly.
Advantages:
- • Compact installation
- • Reduced piping complexity
- • Suitable for industrial skid systems
- • Easy maintenance access
Industries that rely on precise fabrication often procure such assemblies from trusted oil field equipment manufacturer to ensure dimensional accuracy and pressure rating compliance.
Orifice Plate Tapping Locations
Correct orifice plate tapping locations are essential for standard compliance (such as ISO 5167 or ASME guidelines).
| Tapping Type | Upstream Location | Downstream Location |
| Flange Tapping | 1 inch from plate | 1 inch from plate |
| Corner Tapping | At plate face | At plate face |
| D and D/2 | 1D upstream | 0.5D downstream |
| Pipe Tapping | 2.5D upstream | 8D downstream |
Improper placement can significantly impact discharge coefficient and measurement accuracy.
Factors Affecting Tapping Selection
When selecting orifice tapping types, engineers consider:
- • Pipe diameter
- • Operating pressure
- • Fluid type (liquid, gas, steam)
- • Installation space
- • Standard compliance requirements
For high-pressure oil and gas systems, flange tapping is commonly preferred due to compactness and standardization.
Industrial Applications
Orifice tapping systems are used in:
- • Oil and gas production pipelines
- • Steam measurement systems
- • Chemical processing plants
- • Refinery operations
- • Power generation facilities
Proper tapping ensures accurate differential pressure measurement, which directly affects production efficiency.
Installation Best Practices
To ensure accurate flow measurement:
- • Maintain required straight pipe length
- • Avoid turbulence near tapping points
- • Ensure proper alignment of plate and flanges
- • Check tap openings for blockages
- • Use impulse lines of equal length
Regular inspection prevents clogging, especially in gas or slurry applications.
Common Mistakes to Avoid
- • Incorrect tap spacing
- • Improper flange alignment
- • Blocked impulse lines
- • Using non-standard tap dimensions
- • Neglecting calibration
Even small installation errors can produce significant measurement deviations.
Conclusion
Understanding orifice tapping, including various orifice tapping types, is essential for accurate differential pressure flow measurement. Whether using orifice flange tapping, flange tap orifice, or other tapping methods, proper location and installation directly impact performance.
Correct orifice plate tapping locations ensure compliance with industry standards and provide reliable flow data in critical industrial processes.
By selecting the appropriate tapping method and following installation best practices, industries can achieve accurate, efficient, and long-lasting flow measurement performance.
