SAES-Y-101 PDF – Custody Metering of Hydrocarbon Gases

This article is about SAES-Y-101 which is about Custody Metering of Hydrocarbon Gases and download SAES-Y-101 PDF for process and piping engineers, supervisors and project managers, Welding QCs, QC Supervisors. This is saudi aramco standards of Custody Metering Engineering based on international codes and standards and useful for piping and process engineering knowledge to get job as engineers, QC Supervisors and QC managers, Engineering managers and technicians.

SAES-Y-101 PDF Download

SAES-Y-101

Custody Metering of Hydrocarbon Gases

SAES-Y-101 is a standard that establishes the minimum mandatory requirements for the design, construction, and installation of custody transfer metering stations used in the measurement of sales gas and ethane. This standard is likely applicable within the context of Saudi Aramco’s operations.

General Requirements:

1. Approved Vendors: When procuring meters, meter run instruments, and control systems for the custody transfer metering station, it is important to purchase them as a complete integrated system from a single vendor. This ensures that the vendor takes responsibility for the design, fabrication, assembly, and proper functionality of the metering system. Gas custody metering systems should be fabricated by approved vendors, and the list of approved vendors can be obtained from SAES-Y-100. Additionally, instruments, valves, and electrical equipment used in the gas custody metering system should be sourced from approved vendors specified in other relevant standards such as SAES-J-002, SAES-L-102, and SAES-P-101.

Gas custody metering projects should be executed according to the requirements of SAEP-21 or SAEP-50, as applicable. The construction agency, such as SAPMT, is responsible for ensuring that the design and construction contractors deliver a fully operational metering system that complies with both the provisions of this standard and the approved project functional design specifications.

5.2 Classification of Gas Metering Systems:
Gas metering systems are categorized into three classes based on their capacity:

• Small Gas Metering System: Designed for gas flow rates of 20 MMSCFD (million standard cubic feet per day) or less.
• Medium Gas Metering System: Designed for gas flow rates greater than 20 MMSCFD but less than 200 MMSCFD.
• Large Metering System: Designed to handle gas flow rates of 200 MMSCFD or higher.

The specifications for each class of metering systems should meet the specific application requirements outlined in Section 6 of this standard.

Units of Measurement:
All dimensions of the metering skid and associated equipment should be expressed in metric units unless otherwise specified in the project specifications. However, for measurement signals, calculations, and final reporting for billing purposes, the following US Customary units should be used.

Custody Metering General Design

General Design:
Layout:
The gas custody metering system should be designed as a skid-mounted system capable of unattended operation and measurement. The design should ensure that the system can handle 120% of the approved allocated customer demand. If this design exceeds the capacity of the current class of the metering system, it should be designed to meet the requirements of the next higher class. For orifice-based metering systems, the sizing should be such that the Beta Ratio (ratio of orifice bore diameter to pipe diameter) falls between 0.20 and 0.6.

The arrangement of equipment should follow the guidelines outlined in SAES-B-054 to allow for convenient access during operation, maintenance, and replacement. Equipment such as transmitters and gauges should be located at accessible heights from the top of the platform or skid work surface (grating) to ensure ease of access, without obstruction from cross piping or fixed structures. If equipment is located above normal working heights, steps or ladders and operating platforms should be provided.

The original design should include pipe header stubs to allow for the addition of extra meter runs in the future. Blind flanges should be installed at the end of each stub in case a complete shutdown of the metering system is permissible. However, if the metering system cannot tolerate a total shutdown for installing future meter runs, a manually operated block valve with a blinded outlet should be provided at the end of each stub.

The need for filtration in the metering system, especially if there is black powder present in the supply pipeline that could affect downstream equipment, should be determined by the proponent organization.

Two Flow Control Valves (FCVs) should be installed in parallel downstream of the outlet header of the meter runs for medium and large gas metering systems. Each FCV should be able to handle 100% of the maximum flow rate. Upstream and downstream isolation valves should be provided for each FCV. Whenever possible, instrument air should be supplied.

Medium and large gas metering systems should be equipped with a remotely operable isolation valve located outside the meter skid. This valve, installed upstream of the meter skid, should have remote control capability. Unless specified otherwise, this valve falls outside the responsibility of the metering system vendor.

A sample probe and connection for manual sampling should be installed downstream of the meter. If a gas chromatograph (GC) is installed, the outlet of the sample probe should have a suitable connection for manual sampling.

For large gas metering systems, an online GC should be installed. The sample probe should be connected downstream of the meter runs, and the manufacturer should confirm its optimal performance by determining its appropriate location.

For medium gas metering systems, a dedicated online GC should be installed. Alternatively, if a representative gas composition can be obtained from an online GC installed at a common and unique gas supply header, an automatic composite sampling system can be installed upon the request of the proponent. This sampling system collects and stores representative gas samples over a period of one week.

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Read Also:

SAES-Y-100 PDF Download – Regulated Vendors List for Royalty/Custody Measurement Equipment