Gauging and calculation of the volume of LNG unloaded or reloaded The gauging procedures must comply with the recommendations of the current version of the LNG Custody Transfer Handbook of the International Group of Liquefied Natural Gas Importers (GIIGNL). The primary and secondary measuring systems are of capacity, float and/or microwave type; they must comply with standard ISO 18132. The LNG volume unloaded or reloaded, expressed in cubic metres, is determined by the difference between the volumes of LNG contained in the Vessel's tanks before and after the Unloading or Reloading operations. Each of the Vessel's tanks must be equipped with two gauging systems, a main system dedicated to Cargo inspection operations and an emergency system. The maximum permissible error in the primary and secondary gauging systems must not exceed plus or minus 5 mm. The primary and secondary gauging systems must be identified during the Cargo inspection before the Unloading or Reloading operations without modification during these operations. In the event of failure of the main gauging system, the emergency system is used; if its maximum permissible error exceeds plus or minus 5 mm, particularly on an old Vessel, the Shipper and the Operator shall mutually agree on a maximum permissible error greater than +/- 5 mm. The total uncertainty in measuring the LNG volume unloaded or reloaded as a result of the gauging system measurement uncertainty, gauge tables and correction tables associated with each of the Vessel's tanks must be less than 0.3%, in accordance with Council Directive 71/349/EEC of 12 October 1971 transposed into French law. In case the Vessel’s cargo lines used for the Cargo Transfer have not the same filling state during gauging before and after Cargo Transfer: ▪ if the Vessel’s cargo lines are full before Cargo Transfer and empty after Cargo Transfer, the volume of LNG measured before Cargo Transfer is increased by the volume of the cargo lines; ▪ if the Vessel’s cargo lines are empty before Cargo Transfer and full after Cargo Transfer, the volume of LNG measured after Cargo Transfer is increased by the volume of the cargo lines. The volume of the cargo lines is usually provided by the Vessel’s tables: this value is used to increase the volume measured in the tanks. If the volume of the cargo lines is unknown or if the Vessel is not able to provide the relevant tables, a fixed increase of 75 m3 of LNG is applied.
Gauging and calculation of the volume of LNG unloaded or reloaded The gauging procedures must comply with the recommendations of the current version of the LNG Custody Transfer Handbook of the International Group of Liquefied Natural Gas Importers (GIIGNL). The primary and secondary measuring systems are of capacity, float and/or microwave type; they must comply with standard ISO 18132. The LNG volume unloaded or reloaded, expressed in cubic metres, is determined by the difference between the volumes of LNG contained in the Vessel's tanks before and after the Unloading or Reloading operations. Each of the Vessel's tanks must be equipped with two gauging systems, a main system dedicated to Cargo inspection operations and an emergency system. The maximum permissible error in the primary and secondary gauging systems must not exceed plus or minus 5 mm. The primary and secondary gauging systems must be identified during the Cargo inspection before the Unloading or Reloading operations without modification during these operations. In the event of failure of the main gauging system, the emergency system is used; if its maximum permissible error exceeds plus or minus 5 mm, particularly on an old Vessel, the Shipper and the Operator shall mutually agree on a maximum permissible error greater than +/- 5 mm. The total uncertainty in measuring the LNG volume unloaded or reloaded as a result of the gauging system measurement uncertainty, gauge tables and correction tables associated with each of the Vessel's tanks must be less than 0.3%, in accordance with Council Directive 71/349/EEC of 12 October 1971 transposed into French law.
