LNG Supplier in Asia
The client was operating a butane custody transfer skid that relied on a master meter and duty meter regime. Given the commercial sensitivity of butane transfers, the supplier needed to ensure that the overall measurement uncertainty complied with regulatory requirements while also exploring opportunities for improvement.
Key notes
- Industry: Oil & Gas (Custody Transfer/Asian LNG Client)
- System: Master Meter and Duty Meter Coriolis based skid configuration with P&T transmitters, and flow computers
- Impact: Verified <0.25% uncertainty at 95% confidence level; enabled compliance and regulatory acceptance
- By confirming compliance and identifying clear pathways for future optimization, Engineerim enabled the LNG Supplier to safeguard custody transfer accuracy, reduce commercial risk, and plan for strategic upgrades to further enhance measurement integrity.
Engineerim was engaged to calculate the overall measurement uncertainty of the butane metering skid at a specified flow rate. The scope included:
- Coriolis flow meters (master and duty)
- Pressure and temperature transmitters
- Flow computer integration and signal processing
A full evaluation of the master–duty meter arrangement was performed. Each source of error was quantified, combined, and expressed at a 95% confidence level, in line with international standards for custody transfer applications.
The analysis confirmed that the skid’s total expanded uncertainty was within ±0.25% of the regulatory requirement, validating the system’s compliance for custody transfer. Going beyond the basic scope, Engineerim provided the client with additional high-value recommendations:
- Higher accuracy flow meters could further reduce total measurement uncertainty by up to 26%.
- Master meter calibration deviations (observed at ~0.10%) should be carefully tracked over successive calibrations and discussed with the vendor.
- Direct proving with an onsite calibrated prover was highlighted as the best long-term strategy for achieving the lowest possible uncertainty.
- Master–duty meter joint proving was suggested as the next-best option, significantly reducing the impact of master meter calibration uncertainty.
- Signal transmission optimization: replacing analog 4–20 mA inputs with digital communication protocols would eliminate additional uncertainty contributions from flow computer input channels.
The analysis confirmed that the skid’s total expanded uncertainty was within ±0.25% of the regulatory requirement, validating the system’s compliance for custody transfer. Going beyond the basic scope, Engineerim provided the client with additional high-value recommendations:
By confirming compliance and identifying clear pathways for future optimization, Engineerim enabled the LNG Supplier to safeguard custody transfer accuracy, reduce commercial risk, and plan for strategic upgrades to further enhance measurement integrity.