An orifice flange assembly plays a crucial role in accurate flow measurement in pipelines.

It is widely used in industries across Saudi Arabia, the UAE, Oman and Egypt because of its reliability and cost-effectiveness compared to many modern flow technologies.

Yet even the most precisely engineered assembly can deliver poor results if it is not installed correctly. Small installation errors often lead to large inaccuracies, pressure loss, equipment wear and unnecessary downtime.

To help avoid these issues, this guide explains the most common installation mistakes and the best practices recommended by experts and trusted orifice flange assembly suppliers. Whether you are a project engineer, maintenance supervisor or procurement specialist, these points will help ensure long-term accuracy and system stability.

1. Incorrect Orientation of the Orifice Plate

One of the most common mistakes is installing the orifice plate in the wrong orientation. Each plate is designed with a specific direction for the flow.

When installed backward, it immediately affects the differential pressure reading and the flow calculation becomes unreliable.

A backward plate often leads to lower flow readings, increased turbulence and in some cases, permanent plate damage.

Always check for the flow direction mark, typically a tag or engraving on the plate.

During installation, confirm that the beveled edge faces downstream for concentric plates.
You can also refer to orientation guidelines from the International Society of Automation for further clarity.

2. Misalignment Between the Orifice Plate and Pipeline

Even a slight misalignment causes turbulence that disturbs the flow profile.

This is a major reason for inaccurate readings in industries across the UAE, Saudi, Oman and Egypt, especially in older pipeline systems.

Proper alignment requires checking that:

• The orifice plate is centered

• There are no gaps between the plate and the flange

• The gaskets do not intrude into the bore

• The bolts are tightened uniformly

Any deviation leads to unpredictable flow behavior and more frequent calibration requirements. 

3. Gasket Obstruction Inside the Bore

A gasket protruding into the pipe is a small detail that can create a major disruption.

When the gasket overlaps even a few millimeters into the orifice opening, it completely alters the differential pressure. This is one of the simplest mistakes to avoid but also one of the most common during rushed installations.

Use the correct gasket size recommended by reliable suppliers.

Globe United FZE’s orifice flange assembly page provides installation notes and sizing guidance to help prevent gasket misalignment and ensure proper sealing.

4. Insufficient Upstream and Downstream Straight Lengths

Flow measurement depends on achieving a stable and predictable flow profile before the fluid reaches the orifice plate.

If the pipeline has bends, valves or reducers right before the assembly, the flow becomes distorted. This turbulence directly affects accuracy.

Most standards recommend:

• A minimum upstream straight length between 10 to 30 pipe diameters

• A downstream length between 5 to 10 pipe diameters

These guidelines are also supported by industry documents like the Flow Measurement Handbook by Emerson which explains how disturbances affect differential pressure measurement.

However, actual requirements depend on fluid properties and the presence of pipeline disturbances. When space is limited, installing flow conditioners or consulting an expert becomes essential.

5. Improper Installation of Pressure Taps

Pressure taps must be drilled, cleaned and mounted correctly because even a minor error affects the pressure difference measurement. Errors generally include:

• Taps installed at the wrong angle

• Blocked or partially closed taps

• Dirt, rust or weld slag inside the pressure passages

• Different lengths for impulse lines

These issues introduce measurement lag or inconsistent readings.

Always ensure the taps are clear, aligned and free from debris. Technical guidance from InstrumentationTools offers additional troubleshooting insights on tap installation.

6. Uneven Bolt Tightening

Bolts that are not tightened evenly create an irregular seal that can cause leakage or plate warping.

A warped plate distorts the flow profile and causes long-term measurement issues. Use a star-pattern tightening method and follow torque guidelines recommended by the supplier.

This ensures uniform pressure across the flange faces.

7. Neglecting Routine Inspection and Maintenance

Even though orifice flange assemblies are known for their durability, they still require periodic inspection.

Dust, corrosion, scale buildup and worn-out gaskets are common in industrial environments across the Middle East, especially in humid regions of the UAE or dusty environments in Saudi Arabia and Oman.

Regular maintenance includes:

• Cleaning the pressure taps

• Inspecting the orifice plate for wear and tear

• Ensuring the bolts are secure

• Checking for gasket deterioration

• Verifying that impulse lines are not blocked

Routine care prevents costly downtime and keeps flow measurement accurate.
Internal maintenance tips can be found on Globe United FZE’s blog which covers flow equipment care and industry practices.

Best Practices for Proper Installation

Following best installation practices ensures that the orifice flange assembly delivers consistent, reliable and industry-standard readings.

1. Use Assemblies from Trusted Suppliers

Choosing high-quality equipment reduces most installation issues. Leading orifice flange assembly suppliers like Globe United FZE offer assemblies manufactured according to international standards.

Quality equipment ensures better sealing, stable performance, accurate dimensions and long service life.

2. Follow the Manufacturer’s Installation Guide

Every assembly comes with technical instructions that cover orientation, torque values and maintenance procedures. Even an experienced technician should refer to these guidelines. They are made to ensure accuracy and prevent long-term equipment wear.

3. Ensure Proper Pipeline Preparation

Before installing the assembly, check that:

• The pipeline is clean

• The inside surfaces are free from burrs

• There is no foreign material inside the pipe

• The surface where the flanges meet is smooth

Pipeline preparation directly affects performance and is often overlooked.
For detailed pipeline safety guidelines, refer to API’s pipeline standards which outline industry-approved preparation steps.

4. Verify Differential Pressure Transmitter Calibration

The orifice flange assembly works in combination with a DP transmitter. Even if the installation is perfect, incorrect transmitter calibration leads to faulty readings. Ensure calibration matches the fluid properties, expected flow range and operating pressure.

5. Maintain Good Documentation

Record installation details such as:

• Plate orientation

• Tap positions

• Torque values

• Maintenance dates

This helps during troubleshooting and ensures consistent performance across facilities in Oman, Saudi, UAE and Egypt.

To conclude, proper installation of an orifice flange assembly is essential for precision in flow measurement.

Industries in Saudi Arabia, UAE, Oman and Egypt rely heavily on this equipment, so avoiding common mistakes and following best practices can significantly improve accuracy, system reliability and operational efficiency.

Working with trusted orifice flange assembly suppliers such as Globe United FZE adds another layer of assurance because you receive both quality products and expert guidance.