Noise Level Study for PAGA System at NGL Area – DOPET

Noise level standards

iFluids Engineering and Consultancy WLL conducted comprehensive on-site acoustical measurements for noise mapping and analysis to evaluate the Noise Level Study for PAGA (Public Address and General Alarm) System coverage at the NGL (Natural Gas Liquids) area. This study identifies operations, equipment, and subcomponents contributing to noise excesses to ensure regulatory compliance and efficient system design.

Project Background

Qatar Energy operates four NGL plants (NGL-1, NGL-2, NGL-3, and NGL-4) at the Mesaieed NGL Complex in Qatar. The objective is to upgrade outdated control and safety automation systems with modern, proven technologies. These upgrades aim to:

  • Enhance operational safety and efficiency.
  • Centralize management of interfaces and integrations in the existing NGL 1&2 Control Room.

The study included a noise source identification and ranking report, with noise mapping conducted via field noise measurements to ensure compliance with Qatar’s regulatory noise standards.

Scope of the Noise Level Study

  1. Conduct noise level measurements to design the PAGA system for both System-A and System-B configurations at the NGSL area.
  2. Perform on-site acoustical measurements and analyze operations, activities, and equipment contributing to noise excesses.
  3. Map ambient noise levels to AutoCAD files, including noise contour maps.
  4. Submit a comprehensive noise level study report.

Objectives of the Study

  • Record noise levels at PAGA and equipment locations, including ambient and indoor noise for buildings.
  • Use measured sound emission levels and site geometry to generate noise contour maps.
  • Convert noise contour maps into PNG images and shapefiles compatible with AutoCAD.
  • Assess whether process equipment complies with Qatar’s noise regulations and project specifications.

If equipment fails to meet noise limits, mitigation measures such as acoustic insulation or equipment replacement will be recommended.

Noise Study Methodology

Noise study process flow: 1. Data Collection, 2. Modeling, 3. Calculation, 4. Result Analysis, 5. Document Preparation, with feedback for 'Non-compliances' ensuring compliance and precision.
Noise level study process: From data collection to compliant documentation.
  1. Data Collection
    • Gather all necessary documentation for noise monitoring and simulation.
    • Conduct on-site measurements in accordance with ISO 9613 standards for noise assessment.
  2. Simulation Settings
    • Define algorithms for calculations. If not specified, ISO 9613 standards are referenced.
    • Analyze noise levels across the entire project area or specific sensitive receptors.
  3. Field Measurements
    • Use a Type 1 integrated sound level meter for noise level measurements at 221 locations.
    • Perform spot measurements (5 minutes per location) and calculate average daytime noise levels (Leq).
    • Conduct measurements from 6:00 AM to 10:00 AM to represent continuous plant operations.
    • Ensure compliance with Qatar’s State Environmental Protection Law (2002), which limits workplace noise to 85 dB(A) for an 8-hour period.
  4. Key Considerations
    • Calibration of sound level meters before and after measurements.
    • Measurements performed at least 1.5 meters above ground and 3.5 meters away from reflective surfaces.
    • Avoid obstructive elements and adverse climatic conditions during measurements.

Noise Level Criteria

The maximum allowable ambient noise level for industrial zones is 75 dB(A) for both day and night, as per Qatar’s Executive By-Laws (2005) and MIC Guidelines. The Qatar State Environmental Protection Law (2002) stipulates a maximum exposure of 85 dB(A) for 8-hour work periods, with exposure time adjusted based on intensity.

Table showing maximum noise level limits at property lines. For residential and institutional areas: 55 dB(A) in daytime and 45 dB(A) at night. For commercial zones: 65 dB(A) in daytime and 55 dB(A) at night. For industrial zones: 75 dB(A) both during daytime and nighttime.
Noise Level Limits by Zone and Time

Key Findings

  • Workplace noise levels across most areas ranged between 41 dB(A) and 80 dB(A), within the allowable limit of 85 dB(A).
  • Substation building SS-41 recorded noise levels exceeding 85 dB(A) for short durations.
  • The Jetty and loading areas exhibited noise levels closer to 80 dB(A), while most industrial areas remained around 70 dB(A), suitable for normal conversations.
Table showing noise intensity in decibels (dB(A)) and corresponding maximum allowable exposure durations per hour. For 85 dB(A), exposure is 8 hours; for 90 dB(A), exposure is 4 hours; for 95 dB(A), exposure is 2 hours; for 100 dB(A), exposure is 1 hour; for 105 dB(A), exposure is 0.5 hours; for 110 dB(A), exposure is 0.25 hours; and for 115 dB(A), exposure is 0.125 hours
Ensuring safe work conditions by following noise exposure limits

Recommendations

  • For areas exceeding noise limits, consider replacing noisy equipment or implementing noise control measures like acoustic enclosures or insulation.
  • Optimize the PAGA system by:
    • Identifying loudspeaker and junction box locations for adequate coverage.
    • Designing PAGA zones to meet regulatory noise limits and project requirements.

Conclusion

The noise level study ensures compliance with Qatar’s regulatory standards and provides actionable insights for designing an effective PAGA system. The findings emphasize the importance of noise control measures in enhancing workplace safety and maintaining operational efficiency.