Saudi Aramco Royalty/Custody Metering of Hydrocarbon Liquids, SAES-Y-103 describes the minimum mandatory requirements governing the design, construction and installation of metering stations and equipment for royalty and custody transfer measurement of liquid hydrocarbons (e.g., crude oil, petroleum products, butane, nonrefrigerated propane, natural gas liquids). The applications include:
a. Pipeline Shipping/Receiving & Marine Loading/Unloading
b. Truck, Rail Car & Refueler Loading (Distribution Operations)
c. Truck, Rail Car & Refueler Unloading (Distribution Operations)
d. Aircraft Refueling, Defueling and Dispensing (Distribution Operations)
PROCESS & CONTROL SYSTEM DESIGN AND INSTALLATION GUIDELINES
7.1 Systems using Turbine and Positive Displacement Meters
The primary method for measuring liquid petroleum products is a flow meter.
There are currently two types of flow meters approved for use in Saudi Aramco
custody/royalty transfer applications: turbine meter and positive displacement
meter.
Secondary metering methods such as Ultrasonic and Coriolis flow meter may be
used provided they confirm to the specifications described in this manuals and
approved API and ASTM Standards following approval of the technical director of
Custody Measurement Unit.
7.2 Systems using Ultrasonic Flow Meters (UFM)
Acceptance for use of UFM in custody transfer must be reviewed and approved
by the Custody Measurement Unit. Upon approval, the provisions below may be
considered during design and installation of ultrasonic meters for custody transfer
applications:
Only transit time multi-path ultrasonic meters shall be considered.
Provision for data acquisition shall be made at the design phase, so that
this information may be used for ‘foot printing’ and monitoring meter
performance.
Means of meter performance verification is necessary. Acceptable
methods include meter calibration at recognized test facility, using master
meter or conventional pipe prover.
Calibration of the meter shall take place with the flow conditioner and pipe
spools in place.
Provision of suitable pressure and temperature measurement points is
required at both the ‘duty’ and ‘standby’ stations in order that the
appropriate correction volume factors may be applied when comparing the
two meters.
If flow conditioners are proposed as part of the system design then the
type and location of these devices shall be discussed with the meter
manufacturer prior to installation.
The straight pipe sections located immediately upstream and downstream
of the meter shall be selected, fabricated and installed to ensure minimum
impact on the performance of the metering station or the specified
measurement uncertainty.
Note: Meter manufacturers shall be consulted regarding the
minimum number of straight lengths required upstream and
downstream of the meter.
7.3 Systems using Coriolis Meters
Acceptance for use of Coriolis flow meters in custody transfer must be reviewed
and approved by the Custody Measurement Unit/P&CSD. Upon approval, the
provisions below may be considered during design and installation of Coriolis FM
for custody transfer applications.
Place Flow Control Valve downstream of the Coriolis FM to minimize the
potential for ‘flashing’ of lighter hydrocarbons.
If mechanical vibration is present, clamp or mount the meter in order to
minimize this effect of Mechanical vibration, which has the potential to
degrade Coriolis meter performance.
Where the operating temperature is expected to differ significantly from
ambient, consideration to minimize this effect must be applied in the
design and installation of the Coriolis FM.
U-tube devices shall be installed with the ‘U’ vertical to prevent the buildup
of gas within
the meter body.
7.4 Sampling Systems
This manual does not cover Liquefied Petroleum Gases (LPG) or liquids that are
gases at ambient temperature and pressure (Reid vapor pressure above 110 kPa
(16 psig). For LPG sampling systems refer to API MPMS Chapter 14.8.
On-line Analyzers
On-line water analyzers are not accepted for custody transfer measurement, as
there are problems inherent in the comparison of any on-line water analyzer
technology with its ‘sampling’ equivalent.
Manual Sampling
Manual samples obtained from flowing stream in pipelines shall be per API
Manual of Petroleum Measurement Standards, Chapter 8.1 – Manual Sampling of
Petroleum and Petroleum Liquids and Chapter 8.2 – Automatic Sampling of
Petroleum and Petroleum Liquids.
Automatic Sampling
Automatic line sampling systems, either in-line or approved fast-loop systems shall
be installed and maintained in accordance with 34-SAMSS-525.
7.5 Control Systems
All Pipeline and Marine Metering Control Systems shall comply with the design
and installation requirements specified in SAES-Y-103and the references listed
below:
34-SAMSS-841, Flow Computer for Custody Transfer Measurement of
Hydrocarbon Liquids
34-SAMSS-851, Metering Supervisory Computer for Custody Transfer
Measurement of Hydrocarbon Liquids
Flow computer equipment shall be designed such that constants can be adjusted
only by authorized personnel. Where it is necessary to use manual data inputs
within the computer, for such functions as defaults, establishing fallback values
and setting alarm limits, the use of this data shall be automatically logged. Flow
computer configurations shall be checked in accordance with Procedure No. 23 – Flow Computer Configuration Check.
Flow computer manufacturers shall consider the provision of a separate
‘maintenance’ totalization register for use during totalization checks. Totalizers
shall provide resolution sufficient to permit totalization checks to be completed
within a reasonably short time frame and checked in accordance with Procedure
No. 25 – Flow Totalizer Check.
A full set of calculations and input tests shall be carried out when the software is
installed in the flow computer, MSC or PLC. Measurement software shall be
controlled and cataloged in accordance with Procedure No. 26 – Software
Tracking. Meter K-Factor calculation checks shall be performed according to
Procedure No. 28 – K-Factor Calculation Check.