Calibration working standards regime large gas rig


1 Work Standards

In this regime is the following applied:
1.1 Errakal travel standard is once every two years calibrated by NMI.
1.2 The 5 reference meters, the working standards will be compared with the travel standard.
1.3 In the two-year period, the reference meters will be compared for at least four times to the travel standard.  With frequent use, these comparisons are performed more frequently. The ruling is the manager of the rig.
1.4 While performing a calibration a crosscheck is always made between the used reference standards at least at one flow. The flow quantity and the regarded reference meters are dependent on the calibration instrument.


Ad 1.1

The travel standard is only used in the range of comparison / calibration with the Dutch standard of the NMI and to compare / calibrate our standards against the travel standard to guarantee the traceability. Before the travel standard is provided to the NMI for calibration it is first built in the rig to compare all our standards and create calibration curves. The travel standard is transported by Errakal to the NMI and the calibration is witnessed by an Errakal employee. After calibration and transportation the travel standard is stored securely and only used for the equations 2 and 3.


Ad 1.2

After calibration at the NMI and transport to the flow lab the travel standard is built in again and the reference meters are compared to the travel standard. For all the reference standards the curves are made. When observed deviations are greater than 0.2% appropriate measures are taken.


Ad 1.3

Approximately every half year, the reference meters are compared with the travel standard and if deviations greater than 0.2% are found, appropriate measures are taken.


Ad 1.4

During the execution of a calibration or research the reference meters are compared with each other, this means that at least one flow with two or more reference meters a calibration point is determined. Is there a deviation greater than 0.3% calibration is aborted and the appropriate measures are taken.

 

2 Regime for P and T measurements

Pressure Measurements

- All relevant measurements of pressure are calibrated once per year
- The calibration curve obtained is recorded in the electronics to correct input
- At the facility curves are present, to display the pressure at reference standards as a function of the flow
- During a calibration or examination of a quantity surveyor the pressure appointed by system is compared with the graphs
- When differences > 0.5 mbar or suspected defects occur, an additional calibration is inserted

Temperature Measurements

- All relevant measurements of temperature are calibrated once per year
- The correction factor obtained from the calibration is recorded in the electronics
- If during a calibration or examination of a quantity surveyor two identical reference standards are used, the temperatures at these standards are compared
- When differences > 0.2 ° C occur, an additional calibration is inserted 

 

3 Meters of third parties

The calibration of or research on flow meters of third parties are always against the reference standards. The travel standard is never used for this purpose. The calibration of a flow point is measured three times, the values have to be within 0.1%, otherwise there are two additional measurements.