34-samss-112

Previous Issue: 17 September 2007 Next Planned Update: 17 September 2012 Revised paragraphs are indicated in the right margin of 14 Primary contact: Roumi, Sulaiman Hamad on 966-3-8731262

Copyright©Saudi Aramco 2007. All rights reserved.

Materials System Specification

34-SAMSS-112 14 October 2009

Orifice Meter for Gas Custody Measurement

Custody Measurement Standards Committee Members Fadhl, Khalid Ahmed, Chairman Roumi, Sulaiman Hamad, Vice Chairman Awami, Luay Hussain Bakhsh, Abduljalil Hamed Britton, Richard Leo Far, Husain Salah Grainger, John Francis Hijji, Abdullah Saleh Jumah, Yousif Ahmed Khan, Farooq Saeed Louisse, Mart Marri, Saeed Mohammad Othman, Fahad Adel Rockwell Jr., William Allen Sanna'A, Zaki Abbas Shaikh Jaffar, Abdullah Mohammed Torairi, Mohammed Saleh Trembley, Robert James

Saudi Aramco DeskTop Standards Table of Contents 1 Scope............................................................. 2 2 Conflicts and Deviations................................. 2 3 References..................................................... 2 4 Definitions and Abbreviations......................... 4 5 General Requirements................................... 5 6 Orifice Meter Design....................................... 7 7 Meter Tube Design......................................... 9 8 Identification Tagging................................... 11 9 Testing and Inspection................................. 12 10 Shipping Requirements................................ 13 11 Documentation............................................. 13

Document Responsibility: Custody Measurement 34-SAMSS-112

Issue Date: 14 October 2009

Next Planned Update: 17 September 2012 Orifice Meter for Gas Custody Measurement

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1 Scope

This specification defines the minimum mandatory requirements for orifice meters to be

used for the custody transfer measurement of sales gas and ethane.

This specification also defines the minimum mandatory requirements for the upstream

and downstream meter tubes if they are supplied along with the orifice meter by the

meter manufacturer or vendor.

2 Conflicts and Deviations

2.1 Any conflicts between this specification and other applicable Saudi Aramco

Materials System Specifications (SAMSSs), Engineering Standards (SAESs),

Standard Drawings, (SASDs), or industry standards, codes, and forms shall be

resolved in writing by the Company or Buyer Representative through the

Manager, Process & Control Systems Department of Saudi Aramco, Dhahran.

2.2 Direct all requests to deviate from this specification in writing to the Company or

Buyer Representative, who shall follow internal company procedure SAEP-302

and forward such requests to the Manager, Process & Control Systems

Department of Saudi Aramco, Dhahran.

2.3 Direct all requests for interpretation of this specification in writing to the

Company or Buyer Representative who shall forward them to the Chairman,

Custody Measurement Standards Committee for resolution. The Chairman,

Custody Measurement Standards Committee shall be solely responsible for

determining whether a proposed installation meets the requirements of this

specification.

3 References

Material or equipment supplied to this specification shall comply with the latest edition

of the references listed below, unless otherwise noted.

3.1 Saudi Aramco References

Saudi Aramco Engineering Procedure

SAEP-302 Instructions for Obtaining a Waiver of a

Mandatory Saudi Aramco Engineering

Requirement

Saudi Aramco Engineering Standards

SAES-H-001 Coating Selection & Application Requirements for

Industrial Plants & Equipment

http://standards/docs/SAEP/PDF/SAEP-302.PDF

http://standards/docs/SAEP/PDF/SAEP-302.PDF

http://standards/docs/SAES/PDF/SAES-H-001.PDF




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SAES-J-005 Instrumentation Drawings and Forms

SAES-L-105 Piping Material Specifications

SAES-L-109 Selection of Flanges, Stud Bolts and Gaskets

SAES-Y-100 Regulated Vendors List for Custody Measurement

Equipment

Saudi Aramco Materials System Specification

01-SAMSS-010 Fabricated Carbon Steel Piping

Saudi Aramco Standard Drawing

AB-036019 Thermowell Assembly and Detail

Saudi Aramco Forms and Data Sheets

SA-8020-113-ENG ISS for Orifice Meter for Gas Custody

Measurement

NMR-7907 Non Material Requirements for Instrumentation

(General)

3.2 Industry Codes and Standards

American Gas Association

AGA Report 3 Orifice Metering of Natural Gas

American Petroleum Institute, Manual of Petroleum Measurement Standards

API STD 598 Valve Inspection and Testing

API MPMS 14.3.1 Natural Gas Fluids Measurement, Concentric,

Square-Edged Orifice Meters, General

Equations and Uncertainty Guidelines

API MPMS 14.3.2 Natural Gas Fluids Measurement, Concentric

Square Edge Orifice Meters, Specifications and

Installation Requirements

Commentary Note:

AGA Report 3 and API MPMS 14.3.2 are identical documents, so they can be used interchangeably.

American Society of Mechanical Engineers

ASME B16.5 Pipe Flanges and Flanged Fittings

ASME B31.3 Process Piping

http://standards/docs/SAES/PDF/SAES-J-005.PDF

http://standards/docs/SAES/PDF/SAES-L-105.PDF


http://standards/docs/SAES/PDF/SAES-Y-100.PDF

http://standards/docs/SAMSS/PDF/01-SAMSS-010.PDF

http://standards/docs/Standard_Drawings/PDF/AB-036019-001.PDF

http://standards/docs/Forms_Data_Sheets/XLS/SA-8020-113.XLS

http://standards/docs/Nonmaterial_Requirements/PDF/SA-7907.PDF

http://linkmanager.ihs.com/LinkManagerService/LKMLink.aspx?LinkRefName=AGA+REPORT+3-1+-+1990&RefGroupId=30

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http://linkmanager.ihs.com/LinkManagerService/LKMLink.aspx?LinkRefName=API+MPMS+14.3.1+-+1990&RefGroupId=30

http://linkmanager.ihs.com/LinkManagerService/LKMLink.aspx?LinkRefName=API+MPMS+14.3.2&RefGroupId=30



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4 Definitions and Abbreviations

4.1 Definitions

Beta Ratio: The ratio of the orifice bore diameter to the internal diameter of the

pipe.

Buyer or Purchaser: The Company (Saudi Aramco, Aramco Overseas Co., or

Aramco Services Co.) actually placing the order for the material. The buyer can

be a third party metering customer.

Buyer's Representative: The person acting on behalf of the Buyer, who may

be from the Engineering, Inspection, Purchasing, or User Organization.

Custody Transfer Measurement: A specialized form of measurement that

provides quantity and quality information used for the physical and fiscal

documentation of a change in ownership and/or responsibility of commodities.

The following measurements are custody transfer measurements:

Measurement of hydrocarbon liquid or gas movements (deliveries or

receipts) between Saudi Aramco and its customers, suppliers, or transport

contractors.

Measurement of hydrocarbon liquid or gas transfers within, or between,

Saudi Aramco business entities (e.g., refineries, bulk plants, terminals, gas

plants, VELA, etc.) where the measurement is used for accounting or loss

control.

Flow Conditioner: A device that can effectively reduce the swirl component of

a flowing stream and has the ability to produce a flow condition necessary to

perform accurate flow measurement.

Near-shore: Any outdoor, onshore location within one kilometer from the

shoreline of the Arabian Gulf; all of the Ras Tanura Refinery and Terminal; and

within three kilometers from the shoreline of the Red Sea.

Orifice Fitting: Pressure containing piping element used to contain and

position the plate in the piping system.

Orifice Meter: An orifice meter is a fluid flow measuring device that produces

a differential pressure to infer flow rate. It consists of an orifice plate, mounted

in an orifice fitting and equipped with differential pressure sensing taps.

Meter Tubes: The straight upstream pipe and fittings between the flow meter

and the upstream pipe flange and the similar down-stream pipe and fittings

between the flow meter and the pipe flange.




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Orifice Plate: A thin square edge plate with a machined circular bore,

concentric with the meter tube internal diameter when installed.

Vendor: The party that supplies or sells integrated metering systems, metering

equipment, or components.

4.2 Abbreviations

d Orifice Bore Diameter

D Nominal Pipe Diameter

ID Internal Pipe Diameter

ISS Instrument Specification Sheet

5 General Requirements

5.1 Application

This specification together with Instrument Specification Sheet (ISS), Form

SA-8020-113-ENG shall be used as attachments to the Purchase Order.

The Vendor shall submit a completed copy of the specification sheet along with

the bid.

5.2 Approved Vendors

Orifice meters for gas custody measurement shall be supplied by an approved

vendor per SAES-Y-100.

5.3 Scope of Supply

The Vendor shall supply a fully assembled orifice meter as specified in this

SAMSS to perform accurate measurement of gas flow. The orifice meter shall

include the following components as a minimum:

Orifice Plate

Orifice Fitting

The Vendor may also furnish the following items only when specified on the

ISS, Form SA-8020-113-ENG:

Upstream meter tube

Flow Conditioner

Downstream meter tube


http://standards/docs/SAES/PDF/SAES-Y-100.PDF





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5.4 Process Conditions

The orifice meter and all accessories shall be suitable for measuring the process

fluid under the conditions specified on Saudi Aramco Form SA-8020-113-ENG.

5.5 Engineering Units

All dimensions shall be in the "International System of Units" (SI), and shall be

followed by the equivalent value in US Customary between brackets.

The units of flow measurement shall be in US Customary units as specified on

the ISS Form SA-8020-113-ENG.

5.6 Environmental Conditions

5.6.1 Temperature

Equipment and instrumentation shall operate continuously under the

following ambient air temperatures without any degradation of the

manufacturer's guaranteed performance:

Outdoor

Sheltered (1)

Outdoor

Unsheltered

Maximum 55°C

(131°F) 65°C

(149°F)

Minimum 0°C

(32°F) 0°C

(32°F)

Note (1): "Sheltered" refers to permanent, ventilated enclosures or buildings

or permanently fixed sunshades with a top and three sides".

5.6.2 Humidity

Outdoor design basis shall be 5% to 95% relative humidity (non-

condensing).

5.6.3 Offshore and Near-shore Environment

Equipment and instrumentation which is not enclosed or hermetically

sealed, but is situated offshore or near-shore, shall be protected against

corrosion and operational failure due to wind-borne seawater spray and

the accumulation of wetted salt (NaCl).






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6 Orifice Meter Design

6.1 General Requirements

The design and construction of orifice plates shall comply with the requirements

of API MPMS 14.3.2 in addition to the requirements specified in this SAMSS.

Orifice fittings shall be provided to hold the orifice plate. They shall be

designed to be installed in an upright position and shall comply with the

requirements of API MPMS 14.3.2 in addition to the requirements specified in

this SAMSS.

6.2 Orifice Meter Size

The orifice plate bore diameter shall be determined based on a beta ratio

between 0.2 and 0.6 and a maximum differential pressure of 100 inches of water

column to handle the maximum flow rate as specified in Saudi Aramco ISS

Form SA-8020-113-ENG.

The minimum orifice meter nominal pipe size shall be 2" and the minimum

orifice plate bore diameter shall be 0.45". If the orifice meter size or orifice

plate bore diameter falls below the specified limits, then the Chairman of the

Custody Measurement Standards Committee shall be consulted for clarification

and approval.

Commentary Note:

The minimum orifice meter size or orifice plate bore diameter are specified to be within the sizing limits specified in API MPMS 14.3.2 and the uncertainty limits specified in API MPMS 14.3.1.

6.3 Orifice Meter Design Pressure

The orifice meter shall withstand the maximum design pressure as specified in

the ISS Form SA-8020-113-ENG in accordance with ASME B31.3. The

maximum working pressure for the meter shall be consistent with the flange

rating according to ASME B16.5.

6.4 Materials of Construction

Orifice plates shall be constructed of type 316 stainless steel or better.

The wetted parts of the orifice fitting shall be manufactured of material that

provides adequate corrosion resistance and shall be suitable for the gas &

process condition as specified in ISS Form SA-8020-113-ENG.





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The external parts of the meter shall be painted with a corrosion resistance

coating per the manufacturer's standard for surface finishing, priming and

painting. The coating and its application shall be suitable for the environmental

conditions in section 5.6.

6.5 Meter's Performance

The orifice meter shall be designed and fabricated to ensure proper performance

for gas measurement in accordance with AGA Report 3.

6.6 Orifice Meter Components

6.6.1 Orifice Plates

The measured diameter of an orifice plate shall be calculated at a

reference temperature of 60°F according to the calculation of AGA

Report 3. This reference diameter shall be stamped on the plate.

Orifice plates shall be beveled, and the plate faces shall be flat and

smooth as specified in API MPMS 14.3.2.

Orifice plates shall not have weep holes.

6.6.2 Orifice Fittings

6.6.2.1 Orifice fittings can be either double chambers or single

chamber based on the following applications:

Double chamber orifice fittings are required for single

meter run installations in order to allow for orifice plate

inspections and changes without interrupting the gas flow.

Single chamber orifice fittings may be used only in

multitube meter runs installations or where it is possible to

shutdown the station flow to inspect the orifice plate.

6.6.2.2 Orifice fittings shall have flanged ends. The internal diameter

of the fitting shall be matched to that of the tube, within the

tolerances specified in API MPMS 14.3.2.

6.6.2.3 Flanges on orifice fittings shall be the male-female self-

aligning type or shall be doweled with a minimum of three (3)

alignment pins.

6.6.2.4 The orifice fitting shall have flange differential pressure taps.

The center of the upstream tap hole shall be placed 25 mm

from the upstream face of the orifice plate. The center of the









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downstream tap hole shall be 25 mm from the downstream face

of the orifice plate. Tap nipples shall not be seal welded in

orifice fitting.

6.6.2.5 Orifice fitting shall be equipped with bottom chamber drain

valve(s) to allow for chamber blowdown and cleaning. These

valves shall not be seal welded to the orifice fitting.

6.6.2.6 Full opening drain valves shall be installed on the upstream and

downstream sides of the orifice fittings.

6.6.2.7 Orifice fitting assemblies larger than 16 inch size shall be

equipped with lifting davits to enable both orifice plate and

carriers to be lifted to and from the top of the fitting.

6.6.2.8 The orifice plate gasket or sealing device recesses and

protrusions in the fitting shall comply with the requirements of

API MPMS 14.3.2.

6.6.2.9 For double chamber orifice fittings, the chamber isolation

valve shall be of resilient seated construction and shall have

zero leakage. The orifice fitting valve shall be tested per

API STD 598.

7 Meter Tube Design

This section is applicable only when the meter's manufacturer (Vendor) is requested to

supply the meter tubes and flow conditioner along with meter as specified in the ISS

Form SA-8020-113-ENG.

7.1 General Requirements

7.1.1 Piping shall comply with Saudi Aramco standard SAES-L-105 and

specification 01-SAMSS-010.

7.1.2 The design pressure of the metering system piping shall match that of its

interconnecting piping.

7.1.3 The upstream and downstream meter tube sections shall be constructed

of seamless pipe or cold drawn seamless tubing.

7.1.4 The tube shall be as nearly cylindrical as commercially possible with

out-of-roundness deviations (difference between the maximum and

minimum D measurements) not to exceed 0.5% for upstream sections

and 1% for downstream section.


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7.1.5 The inside pipe walls of the meter tubes shall be as smooth as

commercially practicable. The wall roughness of the upstream and

downstream meter tubes shall not exceed the limits specified in

API MPMS 14.3.2. Pipe walls may be machined, ground, coated, honed

and/or polished.

7.1.6 Flanges and fittings welded to meter tubes shall have internal weld joints

ground to a smooth finish, flush with the internal diameter of the pipe

and free of sharp edges or abrupt changes in surface level or diameter.

7.1.7 Flanges and Gaskets shall be as per Saudi Aramco standard SAES-L-109.

Gaskets shall be purchased or trimmed to have at least a 10 mm larger

inside diameter (bore) than the meter tube for 12 inch tube size and above.

For tube size 10 inch and below, gasket internal diameter shall be at least 6

mm larger inside diameter (bore) than the meter tube.

Commentary Note:

This requirement precludes the gasket from protruding into the tube interior through misalignment or compression.

7.1.8 The averages of upstream and downstream meter tube internal diameter

(ID) micrometer readings shall be stamped on a stainless steel data plate

which will be permanently attached to the meter tube.

7.1.9 Flow direction shall be indicated on the meter tube close to each side of

the flow meter.

7.1.10 Protective coating shall be applied on external surfaces of all piping and

equipment and shall be in accordance with Saudi Aramco standard

SAES-H-001.

7.2 Upstream Meter Tube

7.2.1 The upstream meter tube shall consist of two sections with a total

minimum clear length of 20D. A flow conditioner shall be installed in

the middle of the upstream meter tube.

7.2.2 There shall be no pipe connections or fittings within the upstream meter

tubes.

7.2.3 Upstream meter tube ends shall be flanged and equipped with a spacer

ring or jack screw so that the tube sections and the flow conditioner can

be easily removed for inspection and cleaning.

7.2.4 Spacer ring internal diameter shall be 3 mm larger than the meter tube



http://standards/docs/SAES/PDF/SAES-H-001.PDF




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internal diameter and the outer diameter shall be 1.5 mm smaller than the

inside bolt circle of the flange.

7.3 Flow Conditioner

7.3.1 The flow conditioner shall be a uniform concentric 19-Tube Bundle

Flow Straightener as described in API MPMS 14.3.2. It shall be

installed in the middle of the upstream meter tube.

7.3.2 The flow conditioner shall comply with the pressure ratings of the

adjacent piping.

7.3.3 The flow conditioner shall be constructed of carbon steel or better

material that can provide adequate corrosion resistance in the gas

service.

7.3.4 The flow conditioner can be either flange type or line type. It shall be

installed in a way that provides convenient access for ease of inspection,

removal and maintenance.

7.3.5 The flow conditioner shall be securely fastened to prevent it from

vibration or being dislodged and pushed downstream against the orifice

plate.

7.4 Downstream Meter Tube

7.4.1 The downstream meter tube shall have a minimum clear length of 5D.

There shall be no pipe connections or fitting within this 5D downstream

section.

7.4.2 The downstream tube shall have two thermowells made of 316 stainless

steel installed at a distance of at least 5D downstream of the orifice

meter. The thermowells shall be separated by no more than 300 mm.

7.4.3 The thermowells shall be installed in 1 inch NPT tap fittings in

accordance with Saudi Aramco Standard Drawing AB-036019.

8 Identification Tagging

8.1 An identification tag of an AISI Series 300 (Austenitic) type stainless steel shall

be attached to the orifice fitting securely with similar stainless steel or Monel

fasteners. The tag shall be marked by raised letters or die stamping with the

following information and shall be located so that the information can be read

after the equipment is installed:

Manufacturer


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Model Number

Serial Number

Date of Manufacture

Equipment Tag No.

Purchase Order Number

Orifice Fitting Connection Size and Pressure Rating

Certified Internal Pipe Diameter

Material of Body and Trim

8.2 The orifice plate shall be stamped with the Bore Diameter (d) at reference

temperature, Plate Thickness, Material and the word "UPSTREAM" on the

upstream face of the orifice plate.

8.3 Flow direction shall be indicated by an arrow on the orifice fitting and/or by the

words IN and OUT on the piping connections.

8.4 The upstream and downstream meter tubes shall have stainless steel data plate

indicating the averages of tubes internal diameters (ID).

9 Testing and Inspection

9.1 Quality Program

The Vendor shall implement and maintain a Quality Program, which shall

include clearly defined and documented procedures for the relevant Quality

System functions. The Quality Program documents shall be made available to

the Buyer Representative for review and audit.

9.2 Inspection Requirements

The orifice meter and its accessories, and the meter tubes (if provided) are subject

to inspection by the Buyer's Representative in accordance with the requirements

of this material specification and Appendix 2B of API MPMS 14.3.2.

9.3 Dimensional Measurements

The Vendor shall perform dimensional measurements of the critical points of

orifice plate, fitting and meter tubes (if provided) in accordance with

API MPMS 14.3.2 requirements and shall be witnessed by the buyer or its

representative. The measurement results shall be documented and shall be made

available to the Buyer Representative for review.

9.4 Hydrostatic Test






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Hydrostatic test of the orifice meter or the meter tube (if provided) shall be

performed on the fully assembled meter skid by the skid fabricator.

10 Shipping Requirements

10.1 General

All equipment and internals being shipped shall be braced and temporary

supports shall be provided, if required, to prevent damage during shipment.

10.2 Internal Protection

The internals of all piping, fabricated and assembled equipment shall be

completely cleaned and dried to the satisfaction of the Saudi Aramco Inspector.

A non-toxic vapor phase corrosion inhibitor (CORTEC VCI-609, or equivalent)

shall be applied to the internal surfaces of all piping, fabricated and assembled

equipment.

10.3 External Protection

Permanent blind flanges or covers shall be installed at the ends of the orifice

fitting and meter tube (if provided) with the gaskets and bolts required for

service.

All bolts, nuts and the faces of open flanged connections shall be coated with

temporary protective coating such as petroleum paste.

11 Documentation

The vendor shall submit the following documents:

Nonmaterial items as shown on Form NMR-7907.

Operation and maintenance manual(s) of the orifice meter and the associated

accessories

Sizing Calculation

All test results

List of spare parts required for the material supplied

All drawings of the meter tubes (if supplied with the meter)

Documents and drawings shall comply with the requirements of SAES-J-005.

Revision Summary

17 September 2007 New Saudi Aramco Materials System Specification.

http://standards/docs/Nonmaterial_Requirements/PDF/SA-7907.PDF

http://standards/docs/SAES/PDF/SAES-J-005.PDF




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14 October 2009 Editorial revision to read ISS Form SA-8020-113-ENG instead of 8020-112-ENG.