METERING SYSTEM OPERATION | PROCESS & CONTROL SYSTEM
Meters shall be of types in the approved list by SAES-Y-100, Regulated Vendor List for Custody Measurement Equipment. The use of any other type of meters shall be with prior approval of the Technical Director of Custody Measurement Unit.
Single Meters
Turbine meters shall be operated between 40 and 100% of their maximum flow
rate. All new or recently repaired turbine meters shall be calibrated and have
their linearity verified to be ± 0.15 % or better over a 6:1 turndown ratio
(maximum flow rate: minimum flow rate) for acceptance of their calibration curve.
Positive displacement meters shall be operated between 20 and 85 % of their
maximum flow rate. All new or recently repaired positive displacement meters
shall be calibrated and have their linearity verified to be ± 0.15 % or better over
an 8:1 turndown ratio (maximum flow rate: minimum flow rate) for acceptance of
their calibration curve. The meter shall be calibrated using the liquid for which it is
intended or by a liquid whose properties are similar to the liquid for which it is
intended to be used.
Multiple and Standby Meters
Where more than one meter is installed in the same metering system, the number
of meters to be operated at the same time is to be chosen so as to maintain rates
through each individual meter that achieve the following results:
Each meter operates within the manufacturer’s stated minimum and maximum rates.
Each meter operates, in the linear portion of the meter curves.
Each meter operates under conditions that contribute to stable meter factors.
Each meter operates under conditions which will minimize mechanical deterioration
Meters that are part of multiple meter sets should be removed from service if
possible in order to maintain flows above this limit. As meters should not remain idle for extended periods a schedule shall be in place to rotate multiple and standby
meters in order to prevent mechanical deterioration.
Starting and Stopping of Meters
When a meter is first placed in service or after being idle for an extended period,
the meter shall be bled of air, gas, or vapor prior to being placed in service. For
routine stopping and starting of a meter, a valve on the outlet side should be used.
In multiple meter installations adequate meter capacity must be insured to handle
the flow before a meter is taken out of service.
Meter System Failure
Meter failure (loss of registration or inaccurate registration) shall be reported and
the meter removed from service. Operations are responsible for advising as to the
best course of action to be taken. Metering system repair and proving are to be
initiated as soon as possible.
Total Failure of Meter/System to Register
If the meter/system fails completely (does not show registration), it must be
removed from service immediately. Establish the time that the meter/system failed
and approximately how long it will take to repair. The responsible operations
representative shall notify the appropriate contacts and prepare a written report
completely documenting all events leading up to the failure and action taken.
Meters that are out of service or mothballed, shall be proved prior to return to
service. A meter not used for more than a year will be considered out of service
and should be proved before using it.
9.2 SAMPLING SYSTEM OPERATION
Manual Line Sampling
Requirements associated with manual line sampling follow:
Manual line samples will be collected per the instructions specified in
Procedure No. 30 – Manual Pipeline Sampling.
All equipment and procedures used for manual sampling, where applicable,
shall conform to the relevant Standard Laboratory Procedures.
Automatic Sampling Systems
Automatic line sampling systems, either in-line or approved fast-loop systems shall
be installed and maintained in accordance with 34-SAMSS-525. Operational
guidelines associated with automatic sampling systems follow:
All equipment and procedures used for automatic sampling systems where
applicable shall conform to the relevant Standard Laboratory Procedures.
The sample extraction rate for each system shall be set per Procedure No. 31 – Sampler Controller Setting.
Sampler performance shall be monitored to ensure a high level of
confidence in the representative sampling of the system. This monitoring is
required to ensure the sample extractor is collecting a uniform grab in a flow
proportional manner. The procedures for monitoring sampler performance
are listed below:
o Procedure No. 32 – Sampler Grab Size Check
o Procedure No. 33 – Receiver Mixer Homogenization Test
o Procedure No. 34 – Sampler Weighing Systems
The automatic sampling system shall be checked during filling of each
transfer for the following in accordance with Procedure No. 35 – Sample
Receiver Operational Checks:
o Sample containers are filling
o No leaks
o The grab rate set is correct and is applied
o Proper quantity of sample is being collected
Certifying Automatic Sampling Systems
Automatic samplers shall be certified for use after installation by water injection test
per the requirements specified in API MPMS Chapter 8.2 and Procedure No. 36–
Water Injection Test of Automatic Sampling System. Samplers shall be recertified
when normal operating change outside the worse case test conditions under which
the sampler was originally certified.
Automatic Sampling System Failure
In all case of sampler failure Procedure No. 37 – – Sampling System Failure should
be followed.