LIST OF THE CEC PRODUCTS
FLOW METERING PHILOSOPHY
Flow Metering will be classified according to the purpose for which it is required. The classification requires five general levels of accuracy, along with defined rangeability, and calibration as follows:
- Class I – Fiscal Metering (taxation and royalties)
- Class II – Custody Transfer (invoicing for payment)
- Class III- Internal Accounting /Performance Measurement
- Class IV- Control and Protection
- Class V – Indication
Any special requirements regarding taxation and royalties shall be achieved by this Class of metering; otherwise, the measurement for invoicing of payment shall be in accordance with Class II
The measurement shall be fully in accordance with the API Manual on Petroleum Measurement. The type of meter shall be determined according to the application and in agreement with the third party. All straighteners shall be provided in accordance with the API Manual on Petroleum Measurement Standards. Temperature and pressure compensation shall also be provided and shall use the tables in the API Manual on Petroleum Measurement Standards. The accuracy of the temperature and pressure transmitters shall be +/- 0.1% or better.
Turbine meters should be considered for any flow rates especially when exceeding (16,000 m3/d) and where the liquid metered has low viscosity and poor lubricity characteristics. The Ultrasonic Meter can be used the same as the Turbine meter if it has custody transfer approval. The distance between the meter and its prover shall be kept as short as possible. The meter shall be able to operate within linearity of +/- 0.15% or better throughout its normal range. The meter shall be able to reproduce its output within +/- 0.02% or better of meter reading under constant operating conditions.
P.D. meters to be sized to operate between 30% and 80% of nameplate rating. Turbine meters to be sized to operate between 10% and 80% of nameplate rating. Ultrasonic meters to be sized to operate between 5% and 90% of nameplate rating. Coriolis meters should be considered for meter run sizes less than 6″.
Calculation shall be performed in a certified flow computer, and not in the DCS. All instruments shall be calibrated to standards traceable to NIST or other International Standards. The provision for meter proving in the site shall be provided unless agreed otherwise with the third party. One stand-by meter shall be installed. No bypass shall be permitted.
The measurement shall be as in Class II above except that meter proving is not required, and the calculation may be carried out in the FCS. No stand-by meter is required, a bypass valve may be provided, where tank inventory measurement is available or where agreed with the parties involved.
Orifice Plate may be used for this class of measurement as a primary flow element.
LEASE AUTOMATED CUSTODY TRANSFER (LACT)
LACT units are designed for unattended custody transfer of crude oil from a seller to a buyer. The LACT design is determined by:
- Flow rate
- Operating pressure
- Gravity
- The temperature of the oil
Minimum pressure drop through the piping and components is desirable.
LACT units have traditionally been fitted with positive-displacement meters, but a turbine meter can be used with certain types of fluid. New units being built today utilize Coriolis meters because they have no moving parts and can offer a lower cost.
- Current Max Flow Rate 1700 BPH
- ANSI 600 Pressure Rating
- LACT Unit Meter Proving
- Load Rack Meter Proving
- Custody Transfer Metering Skids
- Coriolis, PD & Turbine Meter Proving