Orifice Plate Commissioning Checklist

Proper commissioning of an orifice plate ensures accurate flow measurement and reliable operation in industrial processes. This checklist covers essential steps from preparation and safety considerations to pre-commissioning checks, commissioning procedures, and final documentation.

Step 1: Preparation and Documentation

Before beginning the physical commissioning process, ensure all following necessary documents are gathered and reviewed:

Instrument Loop Diagrams (ILD)

• Obtain detailed loop diagrams showing the complete signal flow from the orifice plate to the control system input.
• Verify that all components tagging, wiring details, and terminal numbers are clearly indicated.
• Cross-check the ILD with the actual installation to ensure accuracy.

Orifice Plate and Transmitter Data Sheets

• Collect manufacturer data sheets for both the orifice plate and transmitter.
• Review the specifications, including type, calibration requirements, flow range, and accuracy characteristics.
• For transmitters, pay special attention to input and output range and signal characteristics.

Instrument Wiring Diagrams

Gather detailed schematics showing all termination locations, wire paths, and connectors.

Ensure these diagrams match the actual installation.

Specification Sheets

• Compile specification sheets for all relevant equipment, including the orifice plate and associated instruments.
• Review these sheets to ensure all installed equipment meets the required specifications.

Loop Folders

• Organize all documents associated with each loop into well-structured folders.
• Include calibration records, maintenance history, and any previous commissioning data if applicable.

P&ID (Piping and Instrumentation Diagrams)

• Obtain the latest version of the P&ID showing process flow, piping details, and instrumentation.
• Verify that the P&ID accurately represents the current installation.

Instrument Location Layout

• Review Instrument Location Layout drawings indicating the physical location of each orifice plate within the process area.
• Confirm that these locations match the actual installation.

Hookup Drawings

• Examine comprehensive installation drawings demonstrating how the orifice plate is connected to related instruments and the process.
• Verify these drawings against the actual installation, noting any discrepancies.

Step 2: Safety Considerations

Before commencing any physical work, ensure all safety protocols are in place:

Work Permits

• Obtain all required work permits for the commissioning process.
• Review site-specific safety protocols with all personnel involved in the commissioning.
• Conduct a safety briefing to ensure everyone understands the potential hazards and safety measures.

Personal Protective Equipment (PPE)

• Ensure all personnel have the appropriate PPE and Verify that all PPE is in good condition and properly fitted.

Safe Work Area

• Establish a clearly defined work area using barriers or tape.
• Post signs to restrict unauthorized access.
• Ensure adequate lighting in the work area.
• Remove any tripping hazards or unnecessary equipment from the area.

Lockout/Tagout

• Implement proper lockout/tagout procedures for all relevant electrical and process equipment.
• Verify that all energy sources have been identified, isolated, and locked out.
• Test to ensure zero energy state before beginning work.

Emergency Equipment

• Locate and ensure access to the nearest: Safety shower, Eye wash station, Fire extinguisher (suitable for electrical fires), First aid kit.
• Verify that all emergency equipment is in working order.
• Ensure all personnel know the locations of emergency equipment and how to use them.

Step 3: Pre-Installation Checks of Orifice Plate

Conduct thorough inspection  before installing the orifice plate:

Verify Orifice Plate Specifications

• Material: Confirm the material (e.g., 316 stainless steel, Hastelloy) matches the specification and is compatible with the process fluid.
• Thickness: Measure the plate thickness using a micrometer and compare to specifications.
• Bore Diameter: Use a precision bore gauge to measure the orifice bore diameter. Compare to specifications.
• Beta Ratio: Calculate the beta ratio (orifice diameter / pipe inside diameter) and verify it matches the design.
• Surface Finish: Inspect the surface finish using a comparator gauge. Ensure smoothness meets specifications.

Confirm Material Compatibility

• Review process fluid composition and verify orifice plate material compatibility.
• Check temperature and pressure ratings against expected process conditions.
• Consider any potential corrosion issues and verify the chosen material is suitable.

Inspect Orifice Plate

• Use a precision straightedge to check for flatness across the entire plate surface.
• Carefully inspect sealing surfaces for nicks, scratches, or other damage.
• Verify the bore edge is sharp and square, with no rounding. Use a magnifying glass if necessary.
• Confirm the correct bevel angle on the downstream side using an angle gauge.

Verify Pipe Specifications

• Confirm pipe material matches specifications.
• Measure wall thickness at multiple points using an ultrasonic thickness gauge.
• Measure internal diameter at several locations using an inside micrometer.
• Check for out-of-round conditions using a dial bore gauge.

Check Upstream and Downstream Straight Pipe Lengths

• For beta < 0.6: Verify minimum 10D upstream straight length.
• For beta ≥ 0.6: Ensure minimum 15D upstream straight length.
• Confirm minimum 5D downstream straight length for all beta ratios.
• If upstream disturbances exist, verify additional straight length as per standards (e.g., ISO 5167).

Click here for Classification of Orifice Plates & Pressure Tappings in Orifice Plate

Inspect Pressure Taps

• Verify tap size (typically 1/4″ or 1/2″) matches specifications.
• Use a borescope to check for burrs or obstructions inside taps.
• Confirm correct orientation (flange or D-D/2 taps) as per design.

Review Piping Layout

• Identify any nearby valves, elbows, or fittings that could disturb flow.
• Check for potential pulsation sources like reciprocating pumps.
• Verify the pipe will be fully filled with process fluid at the orifice location.

Step 4: Installation Procedure of Orifice Plate

Follow these steps for proper orifice plate installation:

Prepare Pipe for Installation

• Clean pipe internals thoroughly using appropriate solvents or cleaning tools.
• Inspect pipe ends for squareness using a machinist’s square.
• Clean flange faces and check for any damage or corrosion.

Prepare Orifice Plate

• Remove any protective coatings from the orifice plate using appropriate solvents.
• Verify the direction arrow points downstream.
• Perform a final inspection for any shipping damage.

Install Orifice Plate

• For large plates, use appropriate lifting equipment to handle safely.
• Ensure the bevel on the orifice plate faces downstream.
• Use alignment pins or a centering tool to properly center the plate in the pipe.
• Use a level to verify the plate is perpendicular to the pipe axis.

Install Gaskets

• Use new gaskets appropriate for the service conditions.
• Verify gasket material is compatible with the process fluid and temperature.
• Carefully install gaskets, ensuring they do not protrude into the flow path.

Assemble Flanges

• Use a calibrated torque wrench for bolt tightening.
• Follow the proper bolt tightening sequence (typically star pattern).
• Tighten bolts in multiple passes, gradually increasing to the final torque value.
• After 24 hours (if possible), re-check and adjust bolt torque as needed.

Verify Final Assembly

• Check flange alignment using a straight edge.
• Inspect for any visible gaps between flanges.
• Confirm the orifice plate tab is visible in the seal plug hole for easy identification.

Click here for Orifice Sizing Guidelines & Rules Associated With Selection

Step 5: Configuration of Instrumentation

Properly install and configure the instrumentation:

Select Differential Pressure Transmitter

• Verify transmitter range matches the expected differential pressure.
• Confirm accuracy class meets or exceeds project requirements.
• Check that wetted parts material is compatible with the process fluid.

Install Transmitter

• Mount the transmitter securely, considering potential vibration issues.
• Ensure easy access for future maintenance and calibration.
• If necessary, provide protection from extreme temperatures (e.g., sunshade, insulation).

Install Impulse Lines

• Use appropriate tubing material and size as per specifications.
• Ensure a continuous slope (minimum 1:10) from the orifice taps to the transmitter.
• Support tubing adequately to prevent sagging.
• If freezing is a concern, install heat tracing on the impulse lines.

Install Valves

• Install block valves at the orifice taps for isolation.
• Add bleed valves for air removal.
• Install an equalizing valve across the transmitter.
• Verify all valve types are suitable for the service conditions.

Wire Transmitter

• Use shielded cable for signal wires to prevent interference.
• Ground the cable shield at one end only to avoid ground loops.
• Seal all conduit entries to prevent moisture ingress.
• Clearly label all wires and terminals for easy identification.

Configure Transmitter

• Set zero and span values according to the calculated differential pressure range.
• Configure damping as required to smooth out fluctuations.
• Set alarm limits if applicable(Flow Switch) to the process.
• Document all configuration settings for future reference.

Step 6: Pre-Commissioning Checks for Orifice Plate 

Perform comprehensive checks on the installed system:

Conduct Leak Test

• Pressurize the system to 1.5 times the normal operating pressure.
• Use a soap solution or gas detector to check all joints and connections.
• Pay special attention to flange joints and impulse line connections.
• Maintain test pressure for at least 1 hour, monitoring for any pressure drop.

Verify Valve Positions

• Confirm all main line valves are fully open.
• Check that any bypass valves are closed.
• Verify transmitter block valves are open.
• Ensure all bleed valves are closed.

Check for Flow Disturbances

• Listen for any unusual noise or vibration in the piping.
• Feel the pipe for excessive vibration.
• If available, use an ultrasonic flow meter to check for swirl in the flow.

Assess Potential for Cavitation

• Calculate the pressure drop across the orifice at maximum flow rate.
• Verify that the downstream pressure is greater than 1.5 times the vapor pressure of the fluid.
• Listen for the characteristic noise of cavitation.

Click here for Orifice Plate Flow and Pressure Drop Calculation Excel Tool

Step 7: Commissioning Tests for Orifice Plate 

Perform detailed commissioning tests to verify system performance:

Perform Zero Check

• Close the block valves and open the equalizing valve.
• Verify the transmitter reads zero (±0.1% of span).
• If necessary, adjust the zero and document the change.

Conduct Flow Tests

• Perform tests at minimum flow, 25%, 50%, 75%, and 100% of range.
• Use an independent flow measurement device for comparison (e.g., portable ultrasonic meter).
• Record all data, including temperatures and pressures.
• Calculate and record flow for each test point.

Refer the below link for the procedure verification of flow rate by using  portable ultrasonic meter.

Check Linearity

• Collect and plot flow rate data at various points.
• Verify linearity is within ±2% of rate across the range.
• Check for causes of deviations and make necessary adjustments.

Assess Pressure Pulsations

• Monitor the differential pressure transmitter output for fluctuations.
• If available, use a high-speed data logger(recorder) to capture rapid changes.
• Calculate the pulsation index and Verify the pulsation index is less than 0.05 for accurate measurement.

Step 8: Documentation of Commissioning Activity

Compile comprehensive documentation of the commissioning process:

Record As-Built Details

• Measure and document the actual pipe internal diameter.
• Record the final orifice bore diameter and plate thickness.
• Document pressure tap locations and sizes.
• Note any deviations from the original design.

Compile Calibration Data

• Include transmitter calibration certificates.
• Document results of on-site calibration checks.
• Record all final configuration parameters.

Update Drawings

• Mark up P&IDs with any changes made during installation.
• Update instrument data sheets to reflect the installed equipment.
• Revise isometric drawings if necessary to show the final installation.

Prepare Commissioning Report

• Summarize all test results.
• Include comparisons with design calculations.
• Note any anomalies or areas for improvement.
• Provide recommendations for ongoing maintenance.

Collect Manufacturer Documentation

• Gather orifice plate material and dimensional certificates.
• Include transmitter manuals and certificates.
• Collect valve datasheets and certificates.

Step 9: Final Inspection and Handover

Perform final checks and prepare for system handover:

Remove Temporary Equipment

• Disconnect and remove all test instruments.
• Ensure all test ports are properly plugged.
• Remove any temporary supports or scaffolding.

Verify Normal Operating Conditions

• Confirm all valves are in the correct position for normal operation.
• Check transmitter output at normal flow conditions.
• Verify system pressure and temperature are within normal ranges.

Check Control System Integration

• Confirm the transmitter signal is correctly received by the control system.
• Verify flow calculations in the control system use the correct parameters.
• Test any alarms or control functions associated with the flow measurement.

Conduct Final Inspection

• Perform a final check for any leaks.
• Ensure all equipment is properly labeled.
• Verify the area is clean and tidy.
• Remove the lockout/tagout and close the work permit.

Prepare Handover Package

• Compile all test results, certificates, and documentation.
• Include marked-up drawings and data sheets.
• Provide the comprehensive commissioning report.
• List any outstanding items or limitations.

Conduct Handover Meeting

• Brief the operations team on installation details and normal operating parameters.
• Discuss any potential issues or watch points.
• Review maintenance requirements and schedules.

Update Maintenance Systems

• Add new equipment to the maintenance database.
• Schedule routine calibration checks.
• Update spare parts inventory as needed.

Plan Follow-up Activities

• Schedule a performance verification after the initial run-in period.
• Arrange any necessary training for operators.
• Plan for future optimizations or improvements.

Downloadable Orifice Plate Commissioning Checklist

Ensure precise flow measurement and reliable performance with our comprehensive Orifice Plate Commissioning Checklist.

This detailed Excel checklist guides engineers through critical steps including pre-installation checks, installation procedures, instrumentation setup, system checks, commissioning tests, documentation, and final checks. 

Follow the link below to download the checklist and streamline your commissioning process.

Click on the link for more Essential Instrumentation Checklists