ISO 17349:2016

Petroleum and natural gas industries - Offshore platforms handling streams with high content of CO2 at high pressures

ISO 17349:2016 contains provisions for design of topside facilities for offshore plants handling CO2-rich streams at high pressures; i.e. CO2 molar concentration above 10 %. The surface systems include usual offshore process unit operations, as shown in Figure 1. ISO 17349:2016 is applicable only to topside facilities of fixed and floating oil and gas production offshore units up to the last barrier, such as an ESDV. Subsea production systems and Cryogenic CO2 separation are not covered.

Industries du pétrole et du gaz naturel — Plates-formes en mer traitant des fluides à forte teneur en CO2 à haute pression

L'ISO 17349:2016 contient des dispositions relatives à la conception des installations de surface d'installations de production en mer qui traitent des fluides riches en CO2 à haute pression, c'est-à-dire des fluides dont la concentration molaire en CO2 est supérieure à 10 %. Les installations de surface concernent les opérations ordinaires des unités de traitement en mer, comme illustré à la Figure 1. L'ISO 17349:2016 s'applique uniquement aux installations de surface des unités fixes et flottantes de production de pétrole et de gaz en mer jusqu'au dernier dispositif de sécurité, tel qu'une vanne d'arrêt d'urgence. Les systèmes de production immergés et la séparation cryogénique du CO2 ne sont pas traités.

General Information

• Status: Published
• Publication Date: 09-Feb-2016
• ICS: 75.020 - Extraction and processing of petroleum and natural gas
• Technical Committee: ISO/TC 67 - Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries
• Drafting Committee: ISO/TC 67 - Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries
• Parallel Committee: ISO/TC 115/SC 3/WG 1 - Joint TC 115/SC 3-TC 67/SC 6 WG : Centrifugal pumps for petroleum and natural gas industries
• Current Stage: 9093 - International Standard confirmed
• Start Date: 01-Nov-2023
• Completion Date: 13-Dec-2025

Relations

• Consolidates: ISO 10003:2007 - Quality management - Customer satisfaction - Guidelines for dispute resolution external to organizations
• Effective Date: 06-Jun-2022

Overview

ISO 17349:2016 - Petroleum and natural gas industries - Guidelines for offshore platforms handling streams with high content of CO2 at high pressures - provides guidance for the design and operation of topside facilities on fixed and floating offshore production units that handle CO2‑rich streams (defined as CO2 molar concentration above 10%). The standard focuses on surface processing (compression, dehydration, hydrocarbon dew‑point control, CO2 separation) up to the last barrier (for example an ESDV). It excludes subsea production systems and cryogenic CO2 separation processes. ISO 17349 supplements existing offshore standards by addressing the unique thermodynamic, materials and safety challenges of dense‑phase and CO2/hydrocarbon mixtures.

Key topics and technical requirements

ISO 17349:2016 covers practical design and safety considerations, including:

• Behavior of CO2‑rich streams: considerations for dense phase, critical and supercritical behavior, EOS (equations of state) selection and validation for CO2/hydrocarbon mixtures.
• Hydrate and solid CO2 formation: assessment and control strategies to prevent hydrate or CO2 solid formation in piping and equipment.
• Flow metering and process control: implications of CO2 properties on measurement accuracy and control systems.
• Depressuring, blowdown and relieving: procedures and design for safe depressurization of CO2‑rich systems (blowdown valve arrangements, depressuring strategies).
• Flare and vent system configuration: selection and configuration guidance for flares and vents, including velocity categorization (e.g., low/high velocity tip flare and vent criteria).
• Materials selection: corrosion, brittle and ductile fracture risks in CO2 environments; guidance on metallic and non‑metallic seals, lubricants and cladding.
• Safety, hazard and consequence analysis: leak consequence modelling, CO2 detection, toxicology considerations, hazard identification, and risk management strategies.
• Informative annexes: practical methodologies (e.g., running ductile fracture evaluation, BLEVE considerations, water content specification, rapid gas decompression).

Applications and users

ISO 17349:2016 is intended for:

• Offshore process and safety engineers designing topside facilities handling CO2‑rich streams.
• Materials and corrosion specialists selecting alloys, seals and linings for CO2 service.
• HSE, risk and integrity management teams conducting hazard identification, consequence analysis and emergency response planning.
• Operators, EPC contractors and regulators seeking guidance to supplement existing offshore standards for projects with significant CO2 content or high‑pressure injection requirements.

Keywords: ISO 17349:2016, CO2‑rich streams, offshore platforms, topside facilities, high pressure, hydrate formation, depressuring, flare and vent, materials selection, safety.

Related standards

Normative and commonly referenced documents include: ISO 13702, ISO 15156 (Parts 1–3), ISO 15544, ISO 19900, ISO 21457, ISO 23251, and ISO 25457. These provide additional requirements for fire/explosion control, materials in sour environments, emergency response, structural requirements and pressure relieving systems.

Standards Content (Sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 17349
ISO/TC 67 Secretariat: NEN
Voting begins on: Voting terminates on:
2014-09-18 2015-02-18
Petroleum and natural gas industries — Guidelines for
offshore platforms handling streams with high content of
CO2 at high pressures
Pétrole et plates-formes en mer de gaz naturel — Courants contenant des niveaux élevés de CO2 sous haute
pression et débits élevés — Lignes directrices
ICS: 75.020
ISO/CEN PARALLEL PROCESSING
This draft has been developed within the International Organization for
Standardization (ISO), and processed under the ISO lead mode of collaboration
as defined in the Vienna Agreement.
This draft is hereby submitted to the ISO member bodies and to the CEN member
bodies for a parallel five month enquiry.
Should this draft be accepted, a final draft, established on the basis of comments
received, will be submitted to a parallel two-month approval vote in ISO and
THIS DOCUMENT IS A DRAFT CIRCULATED
formal vote in CEN.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
To expedite distribution, this document is circulated as received from the
IN ADDITION TO THEIR EVALUATION AS
committee secretariat. ISO Central Secretariat work of editing and text
BEING ACCEPTABLE FOR INDUSTRIAL,
composition will be undertaken at publication stage.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 17349:2014(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2014

ISO/DIS 17349:2014(E)
Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as
permitted under the applicable laws of the user’s country, neither this ISO draft nor any extract
from it may be reproduced, stored in a retrieval system or transmitted in any form or by any means,
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ii © ISO 2014 – All rights reserved

ISO/DIS 17349
Contents Page
Foreword . iv
Introduction . iv
1 Scope . 7
2 Normative references . 8
3 Terms, definitions and abbreviations. 8
3.1 Terms and Definitions . 8
3.2 Abbreviated terms . 10
4 Overview of CO rich streams behavior . 12
4.1 General . 12
4.2 Hydrate formation . 12
4.3 CO solid formation . 12
4.4 Flow metering . 13
5 Blow down, depressuring and relieving of plant and equipment . 13
5.1 Depressuring . 13
6 Flare and vent system configuration . 14
6.1 General . 14
6.2 System selection . 14
6.3 System configuration . 15
7 Materials . 16
7.1 Corrosion . 16
7.2 Brittle fracture . 17
7.3 Ductile fracture . 17
7.4 Lubricants . 17
7.5 Non-metallic seals for CO service . 17
8 Safety . 18
8.1 General . 18
8.2 Impacts of the loss of containment of CO rich streams . 18
8.3 Hazard identification and risk assessment and management . 19
8.4 Consequence analysis . 20
8.5 CO detection . 21
8.6 Strategies . 22
Annex A (informative) Evaluation of EOS for CO rich streams . 23
Annex B (informative) Hydrate formation . 28
Annex C (informative) Water content specification . 32
Annex D (informative) Depressuring of CO rich streams . 38
Annex E (informative) Configuration of flare and vent systems . 41
Annex F (informative) Boiling liquid expanding vapor explosion — BLEVE . 43
Annex G (informative) Methodology for evaluation of running ductile fracture . 45
Annex H (informative) Non-metallic materials for use in CO service . 47
Annex I (informative) CO toxicology information . 48
Bibliography . 51

ISO/DIS 17349
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17349 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries.
iv © ISO 2014 – All rights reserved

ISO/DIS 17349
Introduction
In recent years, the oil industry has been facing challenges in developing and operating high CO content
offshore fields. The CO rich streams, separated from the produced natural gas, may be injected to enhance
oil recovery from the reservoirs. Even in cases where the oil recovery increase is not so significant, operators
have to consider the CO rich stream compression and injection, in order to avoid its venting to the
atmosphere.
Main concerns comprise surface safety system and material selection areas, which lack specific standards
and regulations for this scenario. The commercial tools available, for instance, to model the dispersion of
gases, need to be validated for CO and CO /hydrocarbon mixtures, which have distinctive thermodynamic
2 2
behavior. This will affect the choice of materials and plant design.
This document is intended for guidance only, to improve the industry’s knowledge and to assist developers
and operators to address the issues raised.

DRAFT INTERNATIONAL STANDARD ISO/DIS 17349

Petroleum and natural gas industries — Guidelines for offshore
platforms handling streams with high content of CO2 at high
pressures
1 Scope
This International Standard provides guidelines for design of topside facilities for offshore plants handling CO
rich streams at high pressures. The surface systems include usual offshore process unit operations, e.g.
compression, dehydration, hydrocarbon dew point control and CO separation. Cryogenic CO separation
2 2
processes are not covered. The actual concentration of CO and other components present in the CO rich
2 2
streams is determined case by case, based on reservoir characteristics, topside plant process selection,
economical evaluations and appropriate regulations. This standard intends to address concepts and criteria
about process with CO rich streams that should be considered as a supplement to existing standards for
offshore installations.
In this document the term “Streams containing high levels of CO ”, henceforth referred to as CO rich streams,
2 2
designates streams with CO molar concentration above 10 %. Pure CO streams and CO streams from
2 2 2
combustion processes are not covered.
This International Standard is applicable only to topside facilities of fixed and floating oil and gas production
offshore units. Subsea production systems are not covered. Figure 1 shows an example of Oil and Gas
Platform Process and the highlighted scope of this International Standard.
Pipeline /
Gas Lift
Gas Treated Gas Flare and/or
Export Gas
Injection Compression Vent
Compression
Manifold for Injection
Gas
Injection Wells
CO rich stream CO rich stream
2 2
Injection Compression /
Manifold Pumping
CO
Injection Wells
Produced Gas
Produced Gas Produced Gas CO
Dew Point
Compression Dehydration Separation
Control
Gas/Liquid Separation Plant Low Pressure Gas
Production
Oil Treatment Plant Compression
Manifold
Water Treatment Plant System
Oil Tanks or Treated Water
Fluids from Wells
Pipelines Disposal
Figure 1 — Example of a Process Flow Diagram that is within Scope of this Standard (in grey zone)
ISO/DIS 17349
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 13702, Petroleum and natural gas industries — Control and mitigation of fires and explosions on offshore
production installations — Requirements and guidelines first edition
ISO 15156-1, Petroleum and natural gas industries — Materials for use in H S–containing environments in oil
and gas production — Part 1: General principles for selection of — cracking-resistant materials
ISO 15156-2, Petroleum and natural gas industries — Materials for Use in H S–containing environments in oil
and gas production — Part 2: Cracking-resistant carbon and low-alloy steels, and the use of cast irons
ISO 15156-3, Petroleum and natural gas industries — Materials for Use in H S–containing environments in oil
and gas production — Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys
ISO 15544, Petroleum and natural gas industries — Offshore production installations — Requirements and
guidelines for emergency response
ISO 19900, Petroleum and natural gas industries — General requirements for offshore structures
ISO 21457, Petroleum, petrochemical and natural gas industries — Materials selection and corrosion control
for oil and gas production systems
ISO 23251, Petroleum and natural gas industries — Pressure relieving and depressuring systems
ISO 25457, Petroleum, petrochemical and natural gas industries — Flare details for general refinery and
petrochemical service
3 Terms, definitions and abbreviations
3.1 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
charpy test
test for determining the energy absorbed in an impact test of metallic materials, also referred as
Charpy V-notch test
3.1.2
compressibility factor
Z
thermodynamic property for modifying the ideal gas law to account for the real gas behavior
3.1.3
critical point
critical point is defined by the critical pressure and temperature of the fluid composition above which the
substance exists as a supercritical fluid
3.1.4
critical pressure
defined as the vapor pressure at the critical temperature
8 © ISO 2014 – All rights reserved

ISO/DIS 17349
3.1.5
critical temperature
defined as the temperature above which liquid cannot be formed by a pressure increase
3.1.6
dense phase
fluid state (supercritical or liquid) above critical pressure
3.1.7
equation of state
EOS
thermodynamic equation describing the state of matter under a given set of physical conditions such as
temperature, pressure and volume
3.1.8
free water
water not dissolved in the CO rich stream, i.e. water exists as a separate phase
Note 1 to entry: This can be pure water, water with dissolved salts, water wet salts, water glycol mixtures or other
mixtures containing water.
3.1.9
gas-assisted flare
flare with gas assistance system in order to increase gas net heating value
3.1.10
high velocity tip flare
flare with gas exit velocities higher than 122 m/s
3.1.11
high velocity vent
vent with gas exit velocities higher than 150 m/s
3.1.12
hydrate
solid, crystalline compound of water and light hydrocarbons or CO , in which the water molecules combine
with the gas molecules to form a solid
3.1.13
internal cladding
metallic coating of CRA in which the bond between the parent metal and liner is metallurgical
3.1.14
low velocity tip flare
flare with gas exit velocities lower than 122 m/s
3.1.15
low velocity vent
vent with gas exit velocities lower than 150 m/s
3.1.16
minimum design temperature
minimum temperature below which the application limits for the materials involved are exceeded
3.1.17
platform
complete assembly including structure, topsides and, where applicable, foundations
[ISO 19900:2002, definition 2.23]
ISO/DIS 17349
3.1.18
rapid gas decompression
RGD
depressurization
explosive decompression
rapid pressure-drop in a high pressure gas-containing system which disrupts the equilibrium between external
gas pressure and the concentration of gas dissolved inside any polymer, with the result that excess gas tries
to escape from the solution at points throughout the material, causing expansion
[ISO 23963-2:2011, definition 3.1.10]
3.1.19
supercritical phase
the fluid state above critical pressure and temperature
3.1.20
topsides
structures and equipment placed on a supporting structure (fixed or floating) to provide some or all of a
platform’s functions
[ISO 19900:2002, definition 2.38]
3.1.21
triple point
the temperature and pressure where CO exists as a gas, liquid and solid simultaneously
3.2 Abbreviated terms
ACGIH American Conference of Governmental Industrial Hygienists
AIV acoustically induced vibration
BLEVE boiling liquid expanding vapor explosion
BDV blow down valve
CO carbon dioxide
CCR central control room
CFD computational fluid dynamics
CRA corrosion resistant alloy
EERS evacuation, escape and rescue strategy
EOS equation of state
ESD emergency shut down
FEA finite element analysis
FES fire and explosion strategy
GHV gross heating value
H S hydrogen sulfide
10 © ISO 2014 – All rights reserved

ISO/DIS 17349
HC hydrocarbon
HP high pressure
HSE health, safety and environment
HVV high velocity vent
IDLH immediately dangerous to life or health
LP low pressure
o
MMSCF million standard cubic feet gas (60 F & 1 atm)
NHV net heating value
NIOSH National Institute for Occupational Safety and Health
NIST National Institute of Standards and Technology
OSHA Occupational Safety & Health Administration
Pa ambient pressure
Pc critical pressure
PEL permissible exposure limit
pha Preliminary Hazard Analysis
ppmv parts per million, volumetric basis
PR EOS Peng-Robinson
PR-HV Peng-Robinson EOS modified by using mixing rule of Huron-Vidal and Peneloux factor
PR-SV Peng-Robinson-Stryjek-Vera
PSV pressure safety valve
PVT pressure, volume, temperature
RGD rapid gas decompression
RO restriction orifice
SCF super critical fluids
STEL short term exposure limit
SRK EOS Soave-Redlich-Kwong
Ta ambient temperature
Tc critical temperature
TLV threshold limit value
TWA time weighed average
ISO/DIS 17349
V maximum permitted velocity, expressed in m/s
max
WEL workplace exposure limits
Z compressibility factor
4 Overview of CO rich streams behavior
4.1 General
In an offshore plant design, CO rich streams may be handled close to or above its critical pressure (dense
[5]
phase) or above its critical pressure and temperature (supercritical phase) . In the latter, some of its
properties are similar to that of a liquid (e.g. density) and other similar to that of a gas (e.g. viscosity). The
physical and thermodynamic properties of the CO rich streams will have an impact on issues like hydrate
formation and depressuring.
The design of a plant handling CO rich streams at high pressures should be conducted using an
EOS supported by experimental data in the range of operations. Examples of this approach are shown in
Annex A. If experimental data are not available, data from thermodynamic based models, including readily
available EOS, may be used taking into account any related uncertainties therefore allowing for sufficient
safety margins.
Particular attention should be given when performing simulations near the critical point due to strong variation
on stream properties and uncertainty on the description of the existing phases. For that reason, equipment
normal operation envelope should avoid critical point region.
4.2 Hydrate formation
CO rich streams may present a potential risk for hydrate formation similar to sweet natural gas, if water is
present (as free water or in gas phase).
For high pressures, CO has an inhibitor effect on hydrate formation, since an increase on the
CO concentration shifts the hydrate equilibrium curve towards low temperatures, as it can be seen in
Annex B.
Dehydration unit design should take into account all operational conditions, including low temperatures that
might occur in process systems and pipeline segments downstream from the offshore plant. Special attention
should be given to the fact that CO tends to increase water holding capacity at higher pressures.
For that reason, depending on CO content in the stream, it is not safe to set a water dew point specification
based on higher pressure requirements only, since water condensation may occur at lower pressures
(see Figure B.1).
As a first approach, a margin of 10 °C on water dew point or a reduction down to 50 % of the water saturation
content should be considered.
An example of moisture content specification for Dehydration Unit is presented in Annex C.
4.3 CO solid formation
Solid formation may be observed in a CO rich stream depending on temperature and pressure. Low
temperatures which lead to solid formation may be achieved during planned and unplanned depressuring
operations, for equipment maintenance purposes and emergency conditions as well. Annex D presents phase
diagram for CO rich streams and discusses solid formation based on experimental and theoretical
calculations.
12 © ISO 2014 – All rights reserved

ISO/DIS 17349
[6]
The influence of methane content in solid formation temperature has already been evaluated and published .
The frost point is presented for a CO -CH mixture in a wide range of concentrations, showing that increasing
2 4
CH content shifts the frost point curve toward lower temperatures, as shown in Annex D.
[6] [7]
According to available references and , there is an indication that solid formed from a CO rich stream in
low temperature operations may be considered as composed of pure CO . Therefore, in the absence of
experimental data and specific phase diagrams for mixtures with the solid region represented, available phase
diagrams for pure CO may be used as conservative approach, in order to predict the low temperatures in
which solid formation is expected in an offshore plant design.
Process plant design should take into account the predicted low temperatures with additional design margin in
order to specify suitable mitigation measures to avoid or deal with solid formation. More details are presented
in Clause 5.
4.4 Flow metering
Design of metering systems has to take into account the peculiarities of behavior of CO rich streams.
Preferably, metering systems should be located in plant sections where physical and transport properties are
stable and predictable, i.e., far from critical point or phase transitions. Depending on the process, this means
[8]
some meters may be designed for gas phase, while others for liquid phase .
Flow computers with input for composition as well as temperature and pressure online measurements using
the AGA-8 method, commonly used for natural gas, may be extended to CO rich streams as long as
[9]
conditions guarantee gas phase . AGA-8 method also shows good predictability of supercritical phase as
shown in Annex A.
Differential pressure flow meters such as orifice plates, Venturi or V-Cone are well suitable and robust,
especially when working at very high pressures. Coriolis meters, being mass flow meters, are less susceptible
to the variation of fluid properties or phase changes as long as no solids are formed but can be limited to
operational pressures due to meter body construction.
Special care should be taken regarding changes in the CO rich stream properties and potential flashing, so
meter sizing and location should be properly selected.
5 Blow down, depressuring and relieving of plant and equipment
Temperature decrease observed in CO rich streams during depressuring depends upon the initial and final
pressures, initial temperature and stream composition.
In order to avoid brittle fracture, minimum temperatures achieved during an isenthalpic depressuring should
be considered for material selection of letdown pressure devices (PSVs, BDVs, ROs) and for the entire low
pressure system. Piping sections upstream the letdown pressure device may also be subjected to low
temperatures and should be designed for co-incident high pressure at minimum temperature.
Apart from low temperature effects, designing relief systems of process plants (equipment or piping) should
consider solid CO formation, hydrate formation, adhesion and two-phase flow analysis.
5.1 Depressuring
Plant design should avoid operational conditions that lead to the triple point and solid formation in order to
prevent plugging, piping erosion and vibration. Annex D presents examples of depressuring route in a phase
diagram for CO rich streams.
Designer should evaluate:
 control of blowdown rate (such as manual assisted operations, restriction orifice or automatic control in
steps);
ISO/DIS 17349
 selection of blowdown relief header backpressure higher than triple point and frost line. In this case
proper transient studies should be carried out for a better evaluation of the whole relief system;
 discharge header arrangement suitable to collect solids on relief system knock-out drum;
 avoiding pockets minimizing bends in pipe segments downstream relief device up to main flare or vent
header;
 use of heat tracing;
 applying the full upstream pressure rating to the blowdown systems in the event of risk of plugging.
For depressuring criteria, designer should comply with the guidance of ISO 23251 requirements even in cases
of non flammable CO rich streams.
ESD system design should consider proper installation of shutdown/isolation valves in order to limit inventory
and thereby minimize trapped fluid amount and potential for incident escalation.
The risk of Rapid Gas Decompression (RGD) damages to non-metallic materials may impose limitations on
the depressuring rate. This scenario should be included in the consequence analysis.
6 Flare and vent system configuration
6.1 General
Flare and Vent systems design shall comply with ISO 23251.
Design of CO rich streams flare and vent systems should consider the following aspects, as a minimum:
 CO rich streams composition and respective minimum net heating values (NHVs);
 Reliable combustion assurance (Flare);
 Proper gas dispersion assurance (Vent);
 CO solid formation (see Clause 4);
 Temperature profile during depressuring (see Clause 5 and Clause 7).
6.2 System selection
Possible flare and vent system configurations are described in Annex E, Table E.1.
In case of H S present in CO rich streams flaring should be preferred instead of venting. For flare systems,
2 2
design should comply with H S destruction temperature, as low NHV streams have lower flame temperature.
For vent systems, design warrants proper H S dispersion studies due to hazard and safety aspects.
Flaring gases with low NHV influences ignition stability and may cause flame extinction. Header and disposal
segregation between low and high NHV releases may be considered as an option.
For streams with NHV lower than 7,5 MJ/m (200 BTU/SCF), which corresponds approximately to a
75 % (molar) CO mixture with methane, vent or gas-assisted low velocity tip flare should be used. Minimum
NHV should be ensured in flare systems to allow flammability and combustion efficiency at the flare tip, by
mixing assistance fuel gas from a reliable source to CO rich streams being relieved. The assistance fuel gas
capacity should be designed for the worst case scenario.
14 © ISO 2014 – All rights reserved

ISO/DIS 17349
3 3
For streams with NHV higher than 7,5 MJ/m (200 BTU/SCF) and lower than 28,1 MJ/m (800 BTU/SCF), high
velocity tip flares are not recommended. The use of such tip compared with low velocity one should be
carefully evaluated. Manufacturer guarantee is required in case the high velocity tip will be used.
For high velocity tip flares, a typical minimum NHV gas mixture to be burned is 28,1 MJ/m (800 BTU/SCF).
This corresponds approximately to a 25 % (molar) CO mixture with methane.
6.3 System configuration
6.3.1 Flare
For units dealing with CO rich streams, alternative flare system for low NHV and/or low temperature may be
considered in additional to typical HP and LP systems.
The ignition of CO rich streams requires a high energy ignition source. Such condition can be achieved by
increasing the number of pilot burners in relation to minimum requirements of pilot manufacturers’
recommendations as detailed in ISO 25457.
To ensure combustion, special attention should be given to flare tip velocities. It is important to take into
account the following considerations: Low velocity flares are those designed for and operated with an exit tip
velocity lower than the maximum permitted velocity, V , as determined by the Formula (1), limited to
max
122 m/s (400 ft/s).
log V NHVK1 K2                                             (1)
max
where
V is the maximum permitted velocity, expressed in m/s;
max
K1 is the constant equal to 28,8;
K2 is the constant equal to 31,7;
NHV is the net heating value expressed in MJ/Sm .
[10]
The method to determine the maximum permitted velocity V is shown in .
max
As a general rule, maximum permitted velocity calculated from formula (1) will dictate flare tip area equivalent
diameter. Effects of low temperature on flame stability may be countered by lowering velocity or adding
assistance gas. Flare tip design will be dictated by flare tip suppliers and experimental evidence should be
required for all critical relief scenarios and/or unproven solutions. Interaction with flare tip suppliers is
recommended from the early phases of design.
Designer should evaluate noise and acoustically induced vibration (AIV) aspects.
Flare thermal design shall comply with ISO 23251, following recommendations about admissible total radiation
fluxes over the working areas, without the need of any heat-shield in the unit.
Dispersion simulations are necessary for defining the following designing aspects: flare length, height, position
and orientation due to dominant wind directions. The snuffed flare scenario should be one of those covered by
dispersion studies, especially considering that low temperature releases are less likely to ignite.
6.3.2 Vent
Vent tip location should be assessed based on dispersion studies, practical safety zones, noise, acoustically
induced vibration (AIV) and thermal radiation in case of accidental ignition scenario.
ISO/DIS 17349
Dispersion simulations, including evaluation of the CO plume, are necessary for defining the following
designing aspects: vent length, height, position and orientation due to dominant wind directions. The final
location of the outlet orifices should assure that the low flow discharges be duly dispersed.
As a general recommendation, the vent tip should be pointing 45° from the horizontal plane in the direction
away from working areas. Some protection against rain may be provided.
When designing the vent system, consideration should be given to the formation of solid CO due to low
temperatures downstream of blowdown/relief valves. If solid CO formation is possible, the vent design should
minimize the potential for blockage.
High velocity vents are recommended whenever possible, in order to reduce potential CO or hydrate plugging,
solid adhesion and improve gas dispersion.
7 Materials
7.1 Corrosion
7.1.1 General
Internal corrosion may be a significant risk to the carbon steel piping and equipment integrity dealing with CO
rich streams in presence of free water. Free water combined with high CO partial pressure is likely to lead to
high corrosion rates. As discussed is Annexes B and C, water may be less likely to drop out from vapor phase
CO rich streams when compared to natural gas.
The presence of H S in combination with free water will have a significant effect on the corrosion rate. The
possibility of oxidizing species ingress in the presence of H S may induce elemental sulphur deposition
leading to higher corrosion rates.
Materials selection shall comply with ISO 21457. Physicochemical and corrosion models used for internal
corrosion evaluation may take into account fugacities effect at high CO contents and high pressures in order
to prevent over-conservative pH and corrosion predictions.
Piping, fittings and equipment with fluids containing H S shall be evaluated according to ISO 15156.
Pipe segments and other parts of the system that can have stagnant conditions (pockets) should be evaluated
carefully for internal corrosion.
7.1.2 Internal corrosion control by dehydration
In general, for carbon steel piping and equipment no internal corrosion protection is required providing that
free water in the CO rich streams is avoided through a strict water content control procedure. This
consideration should be used downstream of the dehydration system. Moisture content monitoring should be
considered as part of piping and equipment design and operation.
Upset conditions and downtimes should be taken into account. This may include dehydration system failure
and dehydration off-spec when specifying critical systems where significant failure cannot be tolerated.
7.1.3 CRAs
Most of CRAs are suitable for wet CO rich streams applications. The use of solid or clad CRAs for corrosion
prevention should be considered for the dehydration system itself and the upstream facilities. Some guidelines
for selecting CRAs are indicated in ISO 21457.
When H S is present materials shall be specified according to ISO 15156.
16 © ISO 2014 – All rights reserved

ISO/DIS 17349
7.1.4 Internal corrosion protecting chemicals
Reliance on pH stabilization and corrosion inhibitors injection may not be an effective way to control CO rich
streams corrosion rates where free water is present. If this approach is to be adopted a qualification program
is recommended, in order to ensure the effectiveness of this solution.
7.1.5 Internal organic coatings
Internal coating for corrosion protection is not recommended where there is a risk of damage such as
detachment from the base pipe material due to RGD, erosion, installation and workovers. Extensive corrosion
[12]
rates are likely to result in sections with coating damages .
7.2 Brittle fracture
If a CO rich stream experiences depressuring it may cool down rapidly as a result of the
Joule-Thomson effect. Selected materials should be suitable for the minimum design temperature. This
applies to both parent metal and welded joints.
These materials with guaranteed low temperature properties should be applied to vessels, pipes, valves and
fittings, including body and internals of pressure relief devices. In addition, the low temperature upstream
pressure let down device in piping sections should be considered (refer to Clause 5).
7.3 Ductile fracture
Piping systems handling CO rich streams are more susceptible to running ductile fractures than those for
natural gas service. When a fracture initiates in a pipe with dense phase CO rich stream and vapor starts to
form, the decompression speed drops rapidly, keeping the pipe subjected to a high loading state. The
selected piping material should resist this high loading state and thus prevent fracture propagation.
Likelihood of fracture propagation depends on piping material and thickness, on operation temperature and
[14]
pressure and on the physical properties of the CO rich stream . A methodology for evaluating ductile
fracture propagation is described in Annex G.
7.4 Lubricants
Petroleum based greases and many synthetic types of greases, used in components such as valves and
pumps, may be deteriorated by CO rich streams. The compatibility of the applied grease with specified CO
2 2
rich streams should be taken into account for the entire operating envelope of pressure and temperature.
The phase equilibrium between different kinds of lubricants and CO indicates a three phase area where two
liquid phases and vapor coexist. These regions should be avoided at lubrication point. Besides, the CO
solubility in the lubricant reduces significantly its viscosity and can also jeopardize lubrication.
There are specific lubricants and greases designed for CO applications. This applies in particular to safety
critical valves such as block valves, check valves and pressure relief valves where lubrication may
significantly affect the ability of the valve to operate in an emergency situation. One possibility is to minimize
the contact between lubricant and gas, so that effects will be reduced.
7.5 Non-metallic seals for CO service
The materials selected should be compatible with all states of the CO rich streams. In a dense phase, CO
2 2
rich streams may behave as an efficient solvent and it can penetrate and saturate some non-metallic materials.
The possibility of swelling during dense phase exposure and explosive decompression damage during rapid
gas decompression should be considered for elastomers sealing. Candidate materials need also to be tested
for the potential low temperature conditions that may occur during a depressurization situation (Joule-
Thomson effect).
ISO/DIS 17349
CO rich streams may cause different types of deterioration mechanisms like swelling and cracks after rapid
decompression of several components, such as: o-rings, seals, gaskets and valve seats.
Non-metallic materials should be qualified to ensure:
 ability to resist destructive decompression (RGD);
 chemical/physical compatibility with CO and other chemical components in the CO stream without
2 2
causing significant decomposing/extraction, swelling, hardening or unacceptable negative impact on
material key properties;
 resistance to full temperature range.
All non-metallic seals and packing elements selected should be qualified for the intended operational
conditions. The standards ISO 23936-1 and ISO 23936-2 should be used as references. Concerning
RGD evaluation, the same procedures should be applied as described in ISO 23936-2, however with modified
acceptance criteria for thermoplastics. In this case, the formation of blisters is not acceptable.
Annex H gives some tests for non-metallic materials commonly used in CO rich stream applications.
8 Safety
8.1 General
Offshore units handling CO rich streams at high pressures are a relatively novel process and, depending on
process conditions and applied technology, complexity may be increased due to fluid dynamic properties of
dense phase CO rich streams. This introduces a number of new hazard management issues that should be
addressed.
8.2 Impacts of the loss of containment of CO rich streams
When the temperature of a CO rich stream plume is below the water dew point temperature in the
atmosphere into which it is being released, water vapor will condense to form a visible cloud. Otherwise, high
temperature and pressure releases will take longer time to be visually perceived.
The visible cloud represents the extent of the water vapor condensation and does not represent the extent of
the CO plume. If a high temperature CO stream is leaking (e.g. a leak from a compressor discharge), no
2 2
visible cloud will be produced.
If the ambient atmosphere into which a CO release flows is dry, the water vapor cloud will be smaller than on
a humid day. As a result, the absence of a visible cloud should not be taken as an indication of the absence of
a CO leak. Otherwise, the presence of a visible cloud should not be taken as an indication of the exclusive
presence of a CO leak.
8.2.1 Respiratory physiological parameters
CO acts both as a stimulant and depressant on the central nervous system. Immediately after exposure to
elevated CO levels, physiological parameters such as ventilation rate, total volume of air inhaled and exhaled
during ventilation, CO partial pressure in the lungs and acidity of the blood increase. An ambient volume
concentration of 3 % CO results in a measurable increase in ventilation rate and volume. CO at this level
2 2
also cause headaches, diffuse sweating, and difficult breathing at complete rest after an exposure period of
[15]
several hours .
If inhaled CO concentration is increased above 3 %, respiratory stimulation then increases sharply until
inspired CO concentration of about 10 % is reached. Between 10 % and 30 % inspired CO , the rate of
2 2
18 © ISO 2014 – All rights reserved

ISO/DIS 17349
increase in respiratory rate and volume reduces per unit of increase in inspired CO , until the concentration
of 30 % CO in oxygen is reached. At this point ventilation suddenly declines and convulsions occur.
8.2.2 Low temperature impact
The venting or release of dense phase CO rich stream to atmosphere will result in a temperature drop that
may be accompanied by phase changes and solid CO . Upon impact with adjacent structures such as
equipment, instruments or electrical systems released jet can potentially cause their failure due to physical
damages and/or cooling effects and be a major threat to the structural and functional integrity of nearby
equipment and devices. Cooling effects are significantly more pronounced if solid CO is formed during
[14]
release .
Furthermore, the cold jet of gas from release and entrained solids at – 78 °C represents a significant hazard to
personnel, since it can lead to cryogenic burns, impact injuries and severe internal injuries due to inhalation of
this cold release.
8.2.3 CO rich stream BLEVE
Due to the severity of the consequences of a BLEVE, it should not be disregarded during design phase.
Annex F discusses the definition of BLEVE and presents a theory for prediction of CO rich streams BLEVE
possible occurrence
...

INTERNATIONAL ISO
STANDARD 17349
First edition
2016-02-15
Petroleum and natural gas
industries — Offshore platforms
handling streams with high content of
CO at high pressures
Industries du pétrole et du gaz naturel — Plates-formes en mer
traitant des courants à fort teneur en CO à haute pression
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
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ii © ISO 2016 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Abbreviated terms . 4
5 Overview of CO -rich streams behaviour . 5
5.1 General . 5
5.2 Hydrate formation . 5
5.3 CO solid formation. 6
5.4 Flow metering . 6
6 Blow down, depressuring and relieving of plant and equipment .6
7 Flare and vent system configuration . 7
7.1 General . 7
7.2 System selection . 7
7.3 System configuration . 8
7.3.1 Flare . 8
7.3.2 Vent . 9
8 Materials . 9
8.1 Corrosion . 9
8.1.1 General. 9
8.1.2 Internal corrosion control by dehydration. 9
8.1.3 CRAs .10
8.1.4 Internal corrosion protecting chemicals .10
8.1.5 Internal organic coatings .10
8.2 Brittle fracture .10
8.3 Ductile fracture .10
8.4 Lubricants .10
8.5 Non-metallic seals for CO service .11
9 Safety .11
9.1 General .11
9.2 Impacts of the loss of containment of CO -rich streams .11
9.2.1 General.11
9.2.2 Respiratory physiological parameters .12
9.2.3 Low temperature impact .12
9.2.4 CO -rich stream BLEVE .12
9.3 Hazard identification and risk assessment and management .12
9.3.1 General.12
9.3.2 Hazard identification.13
9.3.3 Risk assessment and management .13
9.4 Consequence analysis .14
9.4.1 General.14
9.4.2 CO dispersion .14
9.4.3 Effects of cold CO jet .14
9.5 CO detection .14
9.6 Strategies.15
Annex A (informative) Evaluation of EOS for CO -rich streams .16
Annex B (informative) Hydrate formation .22
Annex C (informative) Water content specification .26
Annex D (informative) Depressuring of CO -rich streams .33
Annex E (informative) Configuration of flare and vent systems .37
Annex F (informative) Boiling liquid expanding vapour explosion (BLEVE) .40
Annex G (informative) Methodology for evaluation of running ductile fracture .42
Annex H (informative) Non-metallic materials for use in CO service .44
Annex I (informative) CO toxicology information .45
Bibliography .48
iv © ISO 2016 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries.
Introduction
In recent years, the oil industry has been facing challenges in developing and operating high-CO
content offshore fields. The CO -rich streams, separated from the produced natural gas, can be injected
to enhance oil recovery from the reservoirs. Even in cases where the oil recovery increase is not so
significant, operators have to consider the CO -rich stream compression and injection, in order to avoid
its venting to the atmosphere.
Main concerns comprise surface safety system and material selection areas, which lack specific
standards and regulations for this scenario. The commercial tools available, for instance, to model the
dispersion of gases, need to be validated for CO and CO /hydrocarbon mixtures, which have distinctive
2 2
thermodynamic behaviour. This will affect the choice of materials and plant design.
This International Standard addresses concepts and criteria for processing CO -rich streams, as a
supplement to existing standards for offshore installations.
vi © ISO 2016 – All rights reserved

INTERNATIONAL STANDARD ISO 17349:2016(E)
Petroleum and natural gas industries — Offshore
platforms handling streams with high content of CO at
high pressures
1 Scope
This International Standard contains provisions for design of topside facilities for offshore plants
handling CO -rich streams at high pressures; i.e. CO molar concentration above 10 %. The surface
2 2
systems include usual offshore process unit operations, as shown in Figure 1.
This International Standard is applicable only to topside facilities of fixed and floating oil and gas
production offshore units up to the last barrier, such as an ESDV. Subsea production systems and
Cryogenic CO separation are not covered.
NOTE This example is within the scope of this International Standard.
Figure 1 — Example of a Process Flow Diagram (in grey zone)
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 13702, Petroleum and natural gas industries — Control and mitigation of fires and explosions on
offshore production installations — Requirements and guidelines
ISO 15156 (all parts), Petroleum and natural gas industries — Materials for use in H S-containing
environments in oil and gas production
ISO 21457, Petroleum, petrochemical and natural gas industries — Materials selection and corrosion
control for oil and gas production systems
ISO 23936-1, Petroleum, petrochemical and natural gas industries — Non-metallic materials in contact
with media related to oil and gas production — Part 1: Thermoplastics
ISO 23936-2:2011, Petroleum, petrochemical and natural gas industries — Non-metallic materials in
contact with media related to oil and gas production — Part 2: Elastomers
API STD 521, Pressure-relieving and Depressuring Systems, API Standard, January 2014
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
compressibility factor
Z
thermodynamic property for modifying the ideal gas law to account for the real gas behaviour
3.2
corrosion resistant alloy
CRA
alloy intended to be resistant to general and localized corrosion by oil field environments that are
corrosive to carbon steels
[SOURCE: ISO 15156-1:2015, 3.6]
3.3
dense phase
fluid state (supercritical or liquid) above critical pressure
3.4
equation of state
EOS
thermodynamic equation describing the state of matter under a given set of physical conditions
3.5
free water
water not dissolved in the CO -rich stream
Note 1 to entry: This can be pure water, water with dissolved salts, water wet salts, water glycol mixtures or
other mixtures containing water.
3.6
gas-assisted flare
flare with gas assistance system in order to increase gas net heating value
3.7
high-velocity tip flare
flare with gas exit velocities higher than 122 m/s
3.8
high-velocity vent
vent with gas exit velocities higher than 150 m/s
2 © ISO 2016 – All rights reserved

3.9
hydrate
solid, crystalline compound of water and light hydrocarbons or CO , in which the water molecules
combine with the gas molecules to form a solid
3.10
CRA clad
metallic coating of CRA in which the bond between the parent metal and liner is metallurgical
3.11
low-velocity tip flare
flare with gas exit velocities lower than 122 m/s
3.12
low-velocity vent
vent with gas exit velocities lower than 150 m/s
3.13
minimum design temperature
minimum temperature below which the application limits for the materials involved are exceeded
3.14
platform
complete assembly, including structure, topsides, foundations and stationkeeping systems
[SOURCE: ISO 19900:2013, 3.35]
3.15
rapid gas decompression
RGD
depressurization
explosive decompression
rapid pressure-drop in a high pressure gas-containing system which disrupts the equilibrium between
external gas pressure and the concentration of gas dissolved inside any polymer, with the result that
excess gas tries to escape from the solution at points throughout the material, causing expansion
[SOURCE: ISO 23936-2:2011, 3.1.10]
3.16
supercritical phase
fluid state above critical pressure and temperature
3.17
topsides
structures and equipment placed on a supporting structure (fixed or floating) to provide some or all of
a platform’s functions
Note 1 to entry: For a ship-shaped floating structure, the deck is not part of the topsides.
Note 2 to entry: For a jack-up, the hull is not part of the topsides.
Note 3 to entry: A separate fabricated deck or module support frame is part of the topsides.
[SOURCE: ISO 19900:2013, 3.52]
3.18
triple point
temperature and pressure where CO exists as a gas, liquid and solid simultaneously
4 Abbreviated terms
AIV acoustically induced vibration
BLEVE boiling liquid expanding vapour explosion
BDV blow down valve
CH methane
CO carbon dioxide
CCR central control room
CRA corrosion resistant alloy
EERS evacuation, escape and rescue strategy
EOS equation of state
ESD emergency shut down
FES fire and explosion strategy
GDU gas dehydration unit
H S hydrogen sulfide
HC hydrocarbon
HP high pressure
HSE health, safety and environment
IDLH immediately dangerous to life or health
LP low pressure
MMSCF million standard cubic feet gas (60 °F and 1 atm)
NHV net heating value
NIOSH National Institute for Occupational Safety and Health
NIST National Institute of Standards and Technology
OSHA Occupational Safety and Health Administration
Pa ambient pressure
Pc critical pressure
PEL permissible exposure limit
PHA Preliminary Hazard Analysis
ppmv parts per million, volumetric basis
PR Peng-Robinson EOS
PR-HV Peng-Robinson EOS modified by using mixing rule of Huron-Vidal and Peneloux factor
4 © ISO 2016 – All rights reserved

PR-SV Peng-Robinson-Stryjek-Vera EOS
PSV pressure safety valve
RGD rapid gas decompression
RO restriction orifice
SCF standard cubic feet
SVLE solid-liquid-vapour equilibrium
STEL short-term exposure limit
SRK Soave-Redlich-Kwong EOS
Tc critical temperature
TWA time weighted average
v maximum permitted velocity, expressed in m/s
max
Z compressibility factor
5 Overview of CO -rich streams behaviour
5.1 General
In an offshore plant design, CO -rich streams can be handled close to or above its critical pressure (dense
[8]
phase) or above its critical pressure and temperature (supercritical phase). In the latter, some of its
properties are similar to that of a liquid (e.g. density) and other similar to that of a gas (e.g. viscosity).
The physical and thermodynamic properties of the CO -rich streams will have an impact on issues like
hydrate formation and depressuring.
The design of a plant handling CO -rich streams at high pressures should be conducted using an
EOS supported by experimental data in the range of operations. Examples of this approach are shown
in Annex A. If experimental data are not available, data from thermodynamic based models, including
readily available EOS, should be used taking into account any related uncertainties therefore allowing
for sufficient safety margins.
Particular attention should be given when performing simulations near the critical point due to strong
variation on stream properties and uncertainty on the description of the existing phases. For that
reason, equipment normal operation envelope should avoid critical point region.
5.2 Hydrate formation
CO -rich streams can present a potential risk for hydrate formation similar to sweet natural gas, if
water is present (as free water or in gas phase).
For high pressures, CO has an inhibitor effect on hydrate formation, since an increase on the
CO concentration shifts the hydrate equilibrium curve towards low temperatures, as it can be
seen in Annex B.
Dehydration unit design should take into account all operational conditions, including low temperatures
that might occur in process systems and pipeline segments downstream from the offshore plant. Special
attention should be given to the fact that CO tends to increase water-holding capacity at higher pressures.
For that reason, depending on CO content in the stream, it is not safe to set a water dew point
specification based on higher pressure requirements only, since water condensation can occur at lower
pressures (see Figure B.1).
As a first approach, a margin of 10 °C on water dew point or a reduction down to 50 % of the water
saturation content should be considered.
An example of moisture content specification for Dehydration Unit is presented in Annex C.
5.3 CO solid formation
Solid formation can be observed in a CO -rich stream depending on temperature and pressure. Low
temperatures that lead to solid formation can be achieved during planned and unplanned depressuring
operations, for equipment maintenance purposes and emergency conditions as well. Annex D presents
phase diagram for CO -rich streams and discusses solid formation based on experimental and
theoretical calculations.
The influence of methane content in solid formation temperature can be found in Reference [9].
The frost point is presented for a CO -CH mixture in a wide range of concentrations, showing that
2 4
increasing CH content shifts the frost point curve toward lower temperatures, as shown in Annex D.
According to References [9] and [10], there is an indication that solid formed from a CO -rich stream
in low temperature operations may be considered as composed of pure CO . Therefore, in the absence
of experimental data and specific phase diagrams for mixtures with the solid region represented,
available phase diagrams for pure CO may be used as conservative approach, in order to predict the
low temperatures in which solid formation is expected in an offshore plant design.
Process plant design should take into account the predicted low temperatures with additional design
margin in order to specify suitable mitigation measures to avoid or deal with solid formation. More
details are presented in Clause 6.
5.4 Flow metering
Design of metering systems shall take into account the peculiarities of behaviour of CO -rich streams.
Preferably, metering systems should be located in plant sections where physical and transport
properties are stable and predictable, i.e. far from critical point or phase transitions. Depending on the
[11]
process, this means some meters may be designed for gas phase, while others for liquid phase.
Flow computers with input for composition as well as temperature and pressure online measurements
using the AGA-8 method, commonly used for natural gas, may be extended to CO -rich streams as long
[12]
as conditions guarantee gas phase. AGA-8 method also shows good predictability of supercritical
phase as shown in Annex A.
Differential pressure flow meters such as orifice plates, Venturi or V-Cone are well suitable and robust,
especially when working at very high pressures. Coriolis meters, being mass flow meters, are less
susceptible to the variation of fluid properties or phase changes as long as no solids are formed but can
be limited to operational pressures due to meter body construction.
Special care should be taken regarding changes in the CO -rich stream properties and potential
flashing, so meter sizing and location should be properly selected.
6 Blow down, depressuring and relieving of plant and equipment
Temperature decrease observed in CO -rich streams during depressuring depends upon the initial and
final pressures, initial temperature and stream composition.
In order to avoid brittle fracture, minimum temperatures achieved during an isenthalpic depressuring
should be considered for material selection of let-down pressure devices (PSVs, BDVs, ROs) and for the
6 © ISO 2016 – All rights reserved

entire low pressure system. Piping sections upstream the let-down pressure device can also be subjected
to low temperatures and should be designed for co-incident high pressure at minimum temperature.
Apart from low temperature effects, designing relief systems of process plants (equipment or piping)
should consider solid CO formation, hydrate formation, adhesion and two-phase flow analysis.
Plant design should avoid operational conditions that lead to the triple point and solid formation in
order to prevent plugging, piping erosion and vibration. Annex D presents examples of depressuring
route in a phase diagram for CO -rich streams.
Designer should evaluate the following:
— control of blow down rate (such as manual assisted operations, restriction orifice or automatic
control in steps);
— selection of backpressure of the blow down relief header higher than triple point and frost line. In this
case proper transient studies should be carried out for a better evaluation of the whole relief system;
— avoiding pockets and minimizing bends in pipe segments downstream relief device up to main flare
or vent header;
— main flare or vent header configuration to avoid potential plugging;
— use of heat tracing;
— application the full upstream pressure rating to the blow down systems in the event of risk of plugging.
For depressuring criteria, designer shall comply with API STD 521 requirements even in cases of non-
flammable CO -rich streams.
ESD system design should consider proper installation of shutdown/isolation valves in order to limit
inventory and thereby minimize trapped fluid amount and potential for incident escalation.
The risk of Rapid Gas Decompression (RGD) damages to non-metallic materials can impose limitations
on the depressuring rate. This scenario should be included in the consequence analysis.
7 Flare and vent system configuration
7.1 General
Flare and Vent system design shall comply with API STD 521.
Design of CO -rich streams flare and vent systems shall consider the following aspects, as a minimum:
— CO -rich streams composition and respective minimum net heating values (NHVs);
— combustibility (flare);
— safe gas dispersion (vent);
— CO solid formation (see Clause 5);
— temperature profile during depressuring (see Clause 6 and Clause 8);
— selection of metallic and non-metallic materials (see Clause 8).
7.2 System selection
Possible flare and vent system configurations are described in Table E.1.
In case of H S present in CO -rich streams, flaring should be preferred instead of venting. For flare
2 2
systems, design should comply with H S destruction temperature, as low NHV streams have lower
flame temperature. For vent systems, design shall warrant proper H S dispersion due to hazard and
safety aspects.
Flaring gases with low NHV influences ignition stability and can cause flame extinction. Header and
disposal segregation between low and high NHV releases may be considered as an option.
For streams with NHV lower than 7,5 MJ/Sm (200 BTU/SCF), which corresponds approximately to
a 75 % (molar) CO mixture with methane, vent or gas-assisted low-velocity tip flare should be used.
Minimum NHV shall be ensured in flare systems to allow flammability and combustion efficiency at the
flare tip, by mixing assistance fuel gas from a reliable source to CO -rich streams being relieved. The
capacity of assistance fuel gas should be designed for the worst-case scenario.
3 3
For streams with NHV higher than 7,5 MJ/Sm (200 BTU/SCF) and lower than 28,1 MJ/Sm
(800 BTU/SCF), high-velocity tip flares are not recommended. The use of such tip compared with low
velocity one shall be carefully evaluated. Manufacturer guarantee is required in case the high-velocity
tip will be used.
For high-velocity tip flares, a typical minimum NHV gas mixture to be burned is 28,1 MJ/Sm
(800 BTU/SCF). This corresponds approximately to a 25 % (molar) CO mixture with methane.
7.3 System configuration
7.3.1 Flare
For units dealing with CO -rich streams, alternative flare system for low NHV and/or low temperature
may be considered in additional to typical HP and LP systems.
The ignition of CO -rich streams requires a high energy ignition source. Such condition can be achieved
by increasing the number of pilot burners in relation to minimum requirements of pilot manufacturers’
recommendations as detailed in ISO 25457.
To ensure combustion, special attention shall be given to flare tip velocities. It is important to take into
account the following considerations: Low-velocity flares are those designed for and operated with an
exit tip velocity lower than the maximum permitted velocity, v , as determined by the Formula (1),
max
limited to 122 m/s (400 ft/s).
log v =+()NHVK12/K (1)
()
10 max
where
v is the maximum permitted velocity, expressed in m/s;
max
K1 is the constant equal to 28,8;
K2 is the constant equal to 31,7;
.
NHV is the net heating value, expressed in MJ/Sm
The method to determine the maximum permitted velocity v is shown in Reference [13].
max
As a rule, maximum permitted velocity calculated from Formula (1) will dictate flare tip area equivalent
diameter. Effects of low temperature on flame stability can be countered by lowering velocity or adding
assistance gas. Flare tip design will be dictated by flare tip suppliers and experimental evidence
should be required for all critical relief scenarios and/or unproven solutions. Interaction with flare tip
suppliers is recommended from the early phases of design.
Designer should evaluate noise and acoustically induced vibration (AIV) aspects.
Flare thermal design shall comply with API STD 521, following recommendations about admissible
total radiation fluxes over the working areas, without the need of any heat shield in the unit.
8 © ISO 2016 – All rights reserved

Dispersion simulations are necessary for defining the following designing aspects: flare length, height,
position and orientation due to dominant wind directions. The snuffed flare scenario should be one
of those covered by dispersion studies, especially considering that low temperature releases are less
likely to ignite.
7.3.2 Vent
Vent tip location shall be assessed based on dispersion studies, practical safety zones, noise, acoustically
induced vibration (AIV) and thermal radiation in case of accidental ignition scenario.
Dispersion simulations, including evaluation of the CO plume, are necessary for defining the following
designing aspects: vent length, height, position and orientation due to dominant wind directions. The
final location of the outlet orifices shall ensure that the low flow discharges be adequately dispersed.
As a general recommendation, the vent tip should be pointing 45° from the horizontal plane in the
direction away from working areas. Some protection against rain may be provided.
When designing the vent system, consideration should be given to the formation of solid CO due to
low temperatures downstream of blow down/relief valves. If solid CO formation is possible, the vent
design should minimize the potential for blockage.
High-velocity vents are recommended whenever possible, in order to reduce potential CO or hydrate
plugging, solid adhesion and improve gas dispersion.
8 Materials
8.1 Corrosion
8.1.1 General
Internal corrosion can be a significant risk to the carbon steel piping and equipment integrity dealing
with CO -rich streams in presence of free water. Free water combined with high CO partial pressure is
2 2
likely to lead to high corrosion rates. As discussed is Annexes B and C, water can be less likely to drop
out from vapour phase CO -rich streams when compared to natural gas.
The presence of H S in combination with free water will have a significant effect on the corrosion
rate. The possibility of oxidizing species ingress in the presence of H S can induce elemental sulfur
deposition leading to higher corrosion rates.
Materials selection shall comply with ISO 21457. Physicochemical and corrosion models used for internal
corrosion evaluation should take into account considering high CO contents and high pressures.
Piping, fittings and equipment with fluids containing H S shall be evaluated according to ISO 15156 (all
parts).
Pipe segments and other parts of the system that can have stagnant conditions (pockets) should be
evaluated carefully for internal corrosion.
8.1.2 Internal corrosion control by dehydration
In general, for carbon steel piping and equipment no internal corrosion protection is required providing
that free water in the CO -rich streams be avoided through a strict water content control procedure.
This consideration should be used downstream of the dehydration system. Moisture content monitoring
should be considered as part of piping and equipment design and operation.
Upset conditions and downtimes shall be taken into account. This can include dehydration system failure
and dehydration off-spec when specifying critical systems where significant failure cannot be tolerated.
8.1.3 CRAs
Most of CRAs are suitable for wet CO -rich streams applications. The use of solid CRA or CRA clad for
corrosion prevention should be considered for the dehydration system itself and the upstream facilities.
Some guidelines for selecting CRAs are indicated in ISO 21457.
8.1.4 Internal corrosion protecting chemicals
Reliance on pH stabilization and injection of corrosion inhibitors can be an effective way to control CO -
rich streams corrosion rates where free water is present. If this approach is to be adopted a qualification
program is required, in order to ensure the effectiveness of this solution.
8.1.5 Internal organic coatings
Internal coating for corrosion protection is not recommended where there is a risk of damage such as
detachment from the base pipe material due to RGD, erosion, installation and work-overs. Extensive
[14]
corrosion rates are likely to result in sections with coating damages.
8.2 Brittle fracture
If a CO -rich stream experiences depressuring, it can cool down rapidly because of the Joule-Thomson
effect. Selected materials shall be suitable for the minimum design temperature. This applies to both
parent metal and welded joints.
These materials with guaranteed low-temperature properties shall be applied to vessels, pipes, valves
and fittings, including body and internals of pressure relief devices. In addition, the low temperature
upstream pressure let down device in piping sections should be considered (refer to Clause 5).
8.3 Ductile fracture
Piping systems handling CO -rich streams are more susceptible to running ductile fractures than
those for natural gas service. When a fracture initiates in a pipe with dense phase CO -rich stream
and vapour starts to form, the decompression speed drops rapidly, keeping the pipe subjected to a
high loading state. The selected piping material should resist this high loading state and thus prevent
fracture propagation.
Likelihood of fracture propagation depends on piping material and thickness, on operation temperature
[15]
and pressure and on the physical properties of the CO -rich stream. A methodology for evaluating
ductile fracture propagation is described in Annex G.
8.4 Lubricants
Petroleum based greases and many synthetic types of greases, used in components such as valves
and pumps, can be deteriorated by CO -rich streams. The compatibility of the applied grease with
specified CO -rich streams should be taken into account for the entire operating envelope of pressure
and temperature.
The phase equilibrium between different kinds of lubricants and CO indicates a three-phase area where
two liquid phases and vapour coexist. These regions should be avoided at lubrication point. Besides, the
CO solubility in the lubricant reduces significantly its viscosity and can jeopardize lubrication.
There are specific lubricants and greases designed for CO applications. This applies in particular to
safety critical valves such as block valves, check valves and pressure relief valves where lubrication can
significantly affect the ability of the valve to operate in an emergency. One possibility is to minimize the
contact between lubricant and gas, so that effects will be reduced.
10 © ISO 2016 – All rights reserved

8.5 Non-metallic seals for CO service
The materials selected shall be compatible with all states of the CO -rich streams. In a dense phase,
CO -rich streams can behave as an efficient solvent and it can penetrate and saturate some non-
metallic materials.
The possibility of swelling during dense phase exposure and explosive decompression damage during
rapid gas decompression shall be considered for elastomer sealing. Candidate materials need also to
be tested for the potential low temperature conditions that can occur during depressurization (Joule-
Thomson effect).
CO -rich streams can cause different types of deterioration mechanisms like swelling and cracks after
rapid decompression of several components, such as: O-rings, seals, gaskets and valve seats.
Non-metallic materials shall be qualified to ensure the following:
— chemical/physical compatibility with CO and other chemical components in the CO stream without
2 2
causing significant decomposing/extraction, swelling, hardening or unacceptable negative impact
on material key properties;
— resistance to full temperature range;
— ability to resist destructive decompression (RGD).
All non-metallic seals and packing elements selected shall be qualified for the intended design
conditions. ISO 23936-1 and ISO 23936-2 shall be used as references. Concerning RGD evaluation for
thermoplastics, ISO 23936-2 shall be used as reference, however with modified acceptance criteria: no
blisters nor cracks nor holes are acceptable.
Annex H gives some tests for non-metallic materials commonly used in CO -rich stream applications.
9 Safety
9.1 General
Offshore units handling CO -rich streams at high pressures are a relatively novel process and, depending
on process conditions and applied technology, complexity can be increased due to fluid dynamic
properties of dense phase CO -rich streams. This introduces a number of new hazard management
issues that should be addressed.
9.2 Impacts of the loss of containment of CO -rich streams
9.2.1 General
When the temperature of a CO -rich stream plume is below the water dew point temperature in
the atmosphere into which it is being released, water vapour will condense to form a visible cloud.
Otherwise, high temperature and pressure releases will take longer time to be visually perceived.
The visible cloud represents the extent of the water vapour condensation and does not represent the
extent of the CO plume. If a high temperature CO stream is leaking (e.g. a leak from a compressor
2 2
discharge), no visible cloud will be produced.
If the ambient atmosphere into which a CO release flows is dry, the water vapour cloud will be smaller
than on a humid day. As a result, the absence of a visible cloud should not be taken as an indication of
the absence of a CO leak. Otherwise, the presence of a visible cloud should not be taken as an indication
of the exclusive presence of a CO leak.
9.2.2 Respiratory physiological parameters
CO acts both as a stimulant and as depressant on the central nervous system. Immediately after
exposure to elevated CO levels, physiological parameters such as ventilation rate, total volume of
air inhaled and exhaled during ventilation, CO partial pressure in the lungs and acidity of the blood
increase. An ambient volume concentration of 3 % CO results in a measurable increase in ventilation
rate and volume. CO at this level also cause headaches, diffuse sweating, and difficult breathing at
[16]
complete rest after an exposure period of several hours.
If inhaled CO concentration is increased above 3 %, respiratory stimulation then increases sharply
until inspired CO concentration of about 10 % is reached. Between 10 % and 30 % inspired CO , the
2 2
rate of increase in respiratory rate and volume reduces per unit of increase in inspired CO , until
the concentration of 30 % CO in oxygen is reached. At this point ventilation suddenly declines and
convulsions occur.
9.2.3 Low temperature impact
The venting or release of dense phase CO -rich stream to atmosphere will result in a temperature drop
that can be accompanied by phase changes and solid CO . Upon impact with adjacent structures such
as equipment, instruments or electrical systems released jet can potentially cause their failure due to
physical damages and/or cooling effects and be a major threat to the structural and functional integrity
of nearby equipment and
...

NORME ISO
INTERNATIONALE 17349
Première édition
2016-02-15
Industries du pétrole et du gaz
naturel — Plates-formes en mer
traitant des fluides à forte teneur en
CO à haute pression
Petroleum and natural gas industries — Offshore platforms handling
streams with high content of CO at high pressures
Numéro de référence
©
ISO 2016
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2016, Publié en Suisse
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée
sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie, l’affichage sur
l’internet ou sur un Intranet, sans autorisation écrite préalable. Les demandes d’autorisation peuvent être adressées à l’ISO à
l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
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Tel. [phone]
Fax [phone]
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www.iso.org
ii © ISO 2016 – Tous droits réservés

Sommaire Page
Avant-propos .v
Introduction .vi
1 Domaine d’application . 1
2 Références normatives . 2
3 Termes et définitions . 2
4 Abréviations . 4
5 Présentation du comportement des fluides riches en CO . 5
5.1 Généralités . 5
5.2 Formation d’hydrate . 6
5.3 Formation de CO solide . 6
5.4 Mesure du débit . 7
6 Décompression rapide, dépressurisation et purge d’une usine et d’un équipement .7
7 Configuration du système de torche et d’évent. 8
7.1 Généralités . 8
7.2 Choix du système . 8
7.3 Configuration du système . 9
7.3.1 Torche . 9
7.3.2 Évent .10
8 Matériaux .10
8.1 Corrosion .10
8.1.1 Généralités .10
8.1.2 Contrôle de la corrosion interne par déshydratation .10
8.1.3 Alliages résistant à la corrosion (CRA) .11
8.1.4 Produits chimiques protégeant de la corrosion interne .11
8.1.5 Revêtements organiques internes .11
8.2 Rupture fragile .11
8.3 Rupture ductile .11
8.4 Lubrifiants.11
8.5 Dispositifs d’étanchéité non métalliques pour le transport du CO .
2 12
9 Sécurité .12
9.1 Généralités .12
9.2 Effets d’une défaillance du confinement pour les fluides riches en CO .
2 13
9.2.1 Généralités .13
9.2.2 Paramètres de physiologie respiratoire .13
9.2.3 Effets des basses températures .13
9.2.4 BLEVE de fluides riches en CO .
2 13
9.3 Identification des dangers, évaluation et maîtrise des risques .14
9.3.1 Généralités .14
9.3.2 Identification des dangers .14
9.3.3 Évaluation et maîtrise des risques .15
9.4 Analyse des conséquences .15
9.4.1 Généralités .15
9.4.2 Dispersion du CO . .
2 15
9.4.3 Effets du jet de CO froid .16
9.5 Détection du CO .
2 16
9.6 Stratégies.16
Annexe A (informative) Évaluation de l’équation d’état des fluides riches en CO .18
Annexe B (informative) Formation d’hydrate .24
Annexe C (informative) Spécification de la teneur en eau .28
Annexe D (informative) Dépressurisation des fluides riches en CO .36
Annexe E (informative) Configuration des systèmes de torche et d’évent .41
Annexe F (informative) Explosion de vapeurs en expansion au-dessus du liquide en
ébullition (BLEVE) .44
Annexe G (informative) Méthodologie d’évaluation d’une rupture ductile en propagation .47
Annexe H (informative) Matériaux non métalliques à utiliser pour le transport du CO .50
Annexe I (informative) Informations sur la toxicologie du CO .51
Bibliographie .54
iv © ISO 2016 – Tous droits réservés

Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes
nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est
en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.
L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www.
iso.org/directives).
L’attention est appelée sur le fait que certains des éléments du présent document peuvent faire l’objet de
droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de
brevets reçues par l’ISO (voir www.iso.org/brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la signification des termes et expressions spécifiques de l’ISO liés à
l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion de l’ISO aux principes
de l’OMC concernant les obstacles techniques au commerce (OTC), voir le lien suivant: Avant-propos —
Informations supplémentaires.
Le comité chargé de l’élaboration du présent document est l’ISO/TC 67, Matériel, équipement et structures
en mer pour les industries pétrolière, pétrochimique et du gaz naturel.
Introduction
Au cours des dernières années, l’industrie pétrolière a dû faire face à des défis de taille lors du
développement et de l’exploitation en mer de gisements à forte teneur en CO . Les fluides riches en
CO , séparés du gaz naturel produit, peuvent être injectés pour améliorer l’extraction du pétrole des
réservoirs. Même dans les cas où l’amélioration de l’extraction du pétrole n’est pas significative, les
opérateurs doivent envisager la compression et l’injection de fluides riches en CO pour éviter que ce
dernier ne soit déchargé dans l’atmosphère.
Les principaux problèmes rencontrés sont liés au système de sécurité des installations de surface et
au choix des matériaux, pour lesquels il manque des normes et des règlements spécifiques adaptés à ce
scénario. Les outils commerciaux disponibles, par exemple pour modéliser la dispersion des gaz, doivent
être validés pour le CO et les mélanges CO -hydrocarbure, qui ont un comportement thermodynamique
2 2
particulier. Cela a des conséquences sur le choix des matériaux et de la conception des installations.
La présente Norme internationale traite les notions et les critères relatifs au traitement des fluides
riches en CO en complément des normes existantes concernant les installations en mer.
vi © ISO 2016 – Tous droits réservés

NORME INTERNATIONALE ISO 17349:2016(F)
Industries du pétrole et du gaz naturel — Plates-formes
en mer traitant des fluides à forte teneur en CO à haute
pression
1 Domaine d’application
La présente Norme internationale contient des dispositions relatives à la conception des installations
de surface d’installations de production en mer qui traitent des fluides riches en CO à haute pression,
c’est-à-dire des fluides dont la concentration molaire en CO est supérieure à 10 %. Les installations
de surface concernent les opérations ordinaires des unités de traitement en mer, comme illustré à la
Figure 1.
La présente Norme internationale s’applique uniquement aux installations de surface des unités fixes
et flottantes de production de pétrole et de gaz en mer jusqu’au dernier dispositif de sécurité, tel qu’une
vanne d’arrêt d’urgence. Les systèmes de production immergés et la séparation cryogénique du CO ne
sont pas traités.
NOTE Cet exemple relève du domaine d’application de la présente Norme internationale.
Figure 1 — Exemple de diagramme de procédé (zone grisée)
2 Références normatives
Les documents suivants, en totalité ou en partie, sont référencés de manière normative dans le présent
document et sont indispensables pour son application. Pour les références datées, seule l’édition citée
s’applique. Pour les références non datées, la dernière édition du document de référence s’applique (y
compris les éventuels amendements).
ISO 13702, Industries du pétrole et du gaz naturel — Contrôle et atténuation des feux et des explosions
dans les installations en mer — Exigences et lignes directrices.
ISO 15156 (toutes les parties), Industries du pétrole et du gaz naturel — Matériaux pour utilisation dans
des environnements contenant de l’hydrogène sulfuré (H2S) dans la production de pétrole et de gaz.
ISO 21457, Industries du pétrole, de la pétrochimie et du gaz naturel — Choix des matériaux et contrôle de
la corrosion pour les systèmes de production de pétrole et de gaz.
ISO 23936-1, Industries du pétrole, de la pétrochimie et du gaz naturel — Matériaux non métalliques en
contact avec les fluides relatifs à la production de pétrole et de gaz — Partie 1: Matières thermoplastiques.
ISO 23936-2:2011, Industries du pétrole, de la pétrochimie et du gaz naturel — Matériaux non métalliques
en contact avec les fluides relatifs à la production de pétrole et de gaz — Partie 2: Élastomères.
API STD 521, Pressure-relieving and Depressuring Systems, API Standard, January 2014.
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions suivants s’appliquent.
3.1
coefficient de compressibilité
Z
propriété thermodynamique modifiant la loi des gaz parfaits pour rendre compte du comportement
réel du gaz
3.2
alliage résistant à la corrosion
CRA
alliage utilisé pour sa résistance à la corrosion, générale et localisée, dans des milieux pétroliers
corrodant les aciers au carbone
[SOURCE: ISO 15156-1:2015, 3.6]
3.3
phase dense
état du fluide (supercritique ou liquide) au-dessus de la pression critique
3.4
équation d’état
EOS
équation thermodynamique qui décrit l’état de la matière dans un ensemble donné de conditions
physiques
3.5
eau libre
eau non dissoute dans le fluide riche en CO
Note 1 à l’article: Il peut s’agir d’eau pure, d’eau contenant des sels dissous, de sels aqueux humides, de mélanges
eau-glycol ou d’autres mélanges contenant de l’eau.
2 © ISO 2016 – Tous droits réservés

3.6
torche assistée par gaz
torche comportant un système d’assistance par gaz destiné à augmenter le pouvoir calorifique
inférieur du gaz
3.7
torche à brûleur à grande vitesse
torche à vitesse de sortie de gaz supérieure à 122 m/s
3.8
évent à grande vitesse
évent à vitesse de sortie de gaz supérieure à 150 m/s
3.9
hydrate
composé cristallin solide formé d’eau et d’hydrocarbures légers ou de CO , dans lequel les molécules
d’eau se combinent aux molécules de gaz pour former un solide
3.10
CRA en couches minces (clad)
revêtement métallique de CRA dans lequel la liaison entre le métal de base et le chemisage est
métallurgique
3.11
torche à brûleur à faible vitesse
torche à vitesse de sortie de gaz inférieure à 122 m/s
3.12
évent à faible vitesse
évent à vitesse de sortie de gaz inférieure à 150 m/s
3.13
température minimale de conception
température minimale au-dessous de laquelle les limites d’application sont dépassées pour les
matériaux concernés
3.14
plate-forme
assemblage complet comprenant la structure, les installations de surface, les fondations et les systèmes
de maintien en position
[SOURCE: ISO 19900:2013, 3.35]
3.15
décompression rapide des gaz
RGD
dépressurisation
décompression explosive
chute de pression rapide dans un système contenant du gaz sous haute pression, qui rompt l’équilibre
entre la pression de gaz externe et la concentration du gaz dissous à l’intérieur d’un polymère, avec
pour conséquence que le gaz en excès cherche des points de sortie dans tout le matériau en entraînant
une dilatation
[SOURCE: ISO 23936-2:2011, 3.1.10]
3.16
phase supercritique
état du fluide au-dessus de la pression et de la température critiques
3.17
installations de surface
structures et équipements placés sur une structure support (fixe ou flottante) et destinés à remplir
tout ou partie des fonctions dévolues à la plate-forme
Note 1 à l’article: Pour une structure flottante ayant l’architecture d’un navire, le pont ne fait pas partie des
installations de surface.
Note 2 à l’article: Pour une plate-forme auto-élévatrice, la coque ne fait pas partie des installations de surface.
Note 3 à l’article: Un pont fabriqué séparément ou une charpente support de module fait partie des
superstructures.
[SOURCE: ISO 19900:2013, 3.52]
3.18
point triple
température et pression auxquelles le CO existe simultanément à l’état gazeux, liquide et solide
4 Abréviations
AIV vibration acoustique induite (acoustically induced vibration)
BLEVE explosion de vapeurs en expansion au-dessus du liquide en ébullition (boiling liquid expan-
ding vapour explosion)
BDV vanne de décompression rapide (blow down valve)
CH méthane
CO dioxyde de carbone
CCR salle centrale de contrôle (central control room)
CRA alliage résistant à la corrosion (corrosion resistant alloy)
EERS stratégie d’évacuation, de fuite et de sauvetage (evacuation, escape et rescue strategy)
EOS équation d’état (equation of state)
ESD arrêt d’urgence (emergency shut down)
FES stratégie vis-à-vis des feux et des explosions (fire et explosion strategy)
GDU unité de déshydratation du gaz (gas dehydration unit)
H S sulfure d’hydrogène
HC hydrocarbure
HP haute pression
HSE santé, sécurité et environnement (health, safety et environment)
IDLH présentant un danger immédiat pour la vie ou la santé (immediately dangerous to life
or health)
LP basse pression (low pressure)
MMSCF million de pieds cubes en condition standard (gaz) (million standard cubic feet gas) (60 °F
et 1 atm)
4 © ISO 2016 – Tous droits réservés

NHV pouvoir calorifique inférieur (net heating value)
NIOSH National Institute for Occupational Safety et Health
NIST National Institute of Standards et Technology
OSHA Occupational Safety et Health Administration
Pa pression ambiante
Pc pression critique
PEL limite admissible d’exposition (permissible exposure limit)
PHA analyse préliminaire des dangers (Preliminary Hazard Analysis)
ppmv parties par million, en volume
PR équation d’état de Peng-Robinson
PR-HV équation d’état de Peng-Robinson modifiée par la règle de mélange de Huron-Vidal et le
facteur de Peneloux
PR-SV équation d’état de Peng-Robinson-Stryjek-Vera
PSV soupape (pressure safety valve)
RGD décompression rapide des gaz (rapid gas decompression)
RO orifice de restriction (restriction orifice)
SCF pieds cubes en condition standard (standard cubic feet)
SVLE équilibre solide-liquide-vapeur (solid-liquid-vapour equilibrium)
STEL limite d’exposition de courte durée (short-term exposure limit)
SRK équation d’état de Soave-Redlich-Kwong
Tc température critique
TWA moyenne pondérée dans le temps (time weighted average)
v vitesse maximale autorisée, exprimée en m/s
max
Z coefficient de compressibilité
5 Présentation du comportement des fluides riches en CO
5.1 Généralités
Dans la conception d’une installation de production en mer, les fluides riches en CO peuvent être traités
en un point proche ou au-dessus de la pression critique (phase dense) ou au-dessus de la pression et
[8]
de la température critiques (phase supercritique) . Dans le dernier cas, certaines propriétés sont
comparables à celles d’un liquide (par exemple, densité), d’autres à celles d’un gaz (par exemple,
viscosité). Les propriétés physiques et thermodynamiques des fluides riches en CO auront des
conséquences sur des propriétés telles que la formation d’hydrate et la dépressurisation.
Il est recommandé de concevoir une usine qui traite des fluides riches en CO à haute pression en
utilisant une EOS qui repose sur des données expérimentales dans la plage d’opération. L’Annexe A
présente des exemples d’utilisation de cette approche. Si les données expérimentales manquent, il
convient d’utiliser des données provenant de modèles thermodynamiques, y compris des EOS déjà
disponibles, en prenant en compte toute incertitude associée et en prévoyant par conséquent des
marges de sécurité suffisantes.
Il est recommandé d’être particulièrement vigilant lors de la réalisation de simulations autour du point
critique du fait que les propriétés du fluide varient fortement et que la description des phases existantes
est incertaine. C’est pourquoi il convient que l’enveloppe de fonctionnement normal de l’équipement
évite la région du point critique.
5.2 Formation d’hydrate
Les fluides riches en CO présentent un risque potentiel de formation d’hydrate comparable au gaz
naturel doux en présence d’eau (sous forme d’eau libre ou en phase gazeuse).
À haute pression, le CO a un effet inhibiteur sur la formation d’hydrate puisqu’une augmentation de
la concentration en CO déplace la courbe d’équilibre de l’hydrate vers les basses températures, ce que
montre l’Annexe B.
Il convient que la conception de l’unité de déshydratation prenne en compte toutes les conditions de
fonctionnement, y compris les basses températures qui peuvent se présenter dans les systèmes de
traitement et les segments de pipeline en aval de l’installation de production en mer. Il est recommandé
de porter une attention particulière au fait que le CO a tendance à augmenter la capacité de rétention
d’eau à des pressions plus hautes.
C’est pourquoi, en fonction de la teneur du fluide en CO , il n’est pas sans danger de retenir un point de
rosée de l’eau en se basant uniquement sur des exigences des plus hautes pressions puisque l’eau peut
se condenser à des pressions plus basses (voir Figure B.1).
En premier lieu, il est recommandé de retenir une marge de 10 °C pour le point de rosée de l’eau ou de
ramener à 50 % la teneur en eau à l’équilibre de saturation.
L’Annexe C présente un exemple de spécification de teneur en eau pour l’unité de déshydratation.
5.3 Formation de CO solide
On peut observer une formation de solides dans un fluide riche en CO en fonction de la température et
de la pression. Les basses températures qui provoquent une formation de solides peuvent être atteintes
lors d’opérations prévues et non prévues de dépressurisation, aussi bien lors de la maintenance de
l’équipement que dans des conditions d’urgence. L’Annexe D présente le diagramme de phase de fluides
riches en CO et évoque la formation de solides en se basant sur des calculs expérimentaux et théoriques.
L’influence de la teneur en méthane sur la température de formation de solides est décrite dans la
Référence [9]. Cette dernière présente le point de givre d’un mélange CO -CH dans une vaste gamme
2 4
de concentrations et montre qu’une teneur croissante en CH se traduit par le déplacement de la courbe
du point de givre vers les basses températures, comme le montre l’Annexe D.
D’après les Références [9] et [10], il semble que l’on puisse considérer que le solide formé à partir d’un
fluide riche en CO lors d’opérations à basse température soit composé de CO pur. En l’absence de
2 2
données expérimentales et de diagrammes de phases spécifiques pour des mélanges dont la région
solide est représentée, il est donc admis d’utiliser les diagrammes de phases disponibles pour le CO
pur dans une approche conservatrice afin de prévoir les basses températures auxquelles une formation
de solides est attendue lors de la conception d’une installation de production en mer.
Il convient que la conception d’une usine de traitement prenne en compte les basses températures
prévues, assorties de marges supplémentaires de sécurité, afin de spécifier des mesures appropriées
de réduction des risques pour éviter ou contrer la formation de solides. L’Article 6 donne davantage de
détails à ce sujet.
6 © ISO 2016 – Tous droits réservés

5.4 Mesure du débit
La conception des systèmes de mesure doit prendre en compte le comportement particulier des
fluides riches en CO . Il convient que les systèmes de mesure soient situés dans des endroits de l’usine
où les propriétés physiques et les propriétés de transport sont stables et prévisibles, c’est-à-dire loin
des points critiques et des changements de phase. En fonction du procédé, il en résulte que certains
[11]
débitmètres peuvent être conçus pour la phase gazeuse et d’autres pour la phase liquide .
Des calculateurs de débit dont les entrées comprennent des mesures en ligne concernant la composition
ainsi que la température et la pression d’après la méthode AGA-8, couramment utilisés pour le gaz
naturel, peuvent être employés pour les fluides riches en CO du moment que les conditions garantissent
[12]
la phase gazeuse . La méthode AGA-8 permet aussi de prévoir avec précision la phase supercritique,
comme le montre l’Annexe A.
Les débitmètres à pression différentielle comme les diaphragmes, les Venturis ou les V-Cone sont
pratiques et résistants, en particulier à très haute pression. Les débitmètres de Coriolis, qui mesurent
le débit massique, sont moins sensibles aux variations des propriétés du fluide ou aux changements
de phase du moment qu’il n’y a pas formation de solides, mais ils peuvent se limiter aux pressions
fonctionnelles du fait de la structure du corps du débitmètre.
Il est recommandé de porter une attention particulière aux changements subis par les propriétés des
fluides riches en CO et à la vaporisation instantanée qui peut se produire, de sorte qu’il est recommandé
de bien choisir la taille et l’emplacement du débitmètre.
6 Décompression rapide, dépressurisation et purge d’une usine et d’un
équipement
La baisse de température que connaissent les fluides riches en CO pendant la dépressurisation dépend
de la pression initiale et de la pression finale, de la température initiale et de la composition du fluide.
Pour éviter une rupture fragile, il est recommandé de prendre en compte les températures minimales
atteintes lors d’une dépressurisation isenthalpique au moment de choisir les matériaux des dispositifs
de réduction de pression (PSV, BDV, RO) et tout le système basse pression. Les sections de tuyauterie en
amont du dispositif de réduction de pression peuvent aussi être soumises à de basses températures et
il est recommandé de les concevoir conjointement pour la haute pression et la température minimale.
Outre les effets des basses températures, il est recommandé de prendre en compte la formation de CO
solide, la formation et l’adhérence d’hydrates et l’analyse de l’écoulement diphasique au moment de
concevoir les systèmes de décompression d’une usine de traitement (équipement ou tuyauterie).
Lors de la conception de l’usine, il est recommandé d’éviter les conditions de fonctionnement qui
conduisent au point triple et à la formation de solides afin de prévenir l’obturation, l’usure de la
tuyauterie et les vibrations. L’Annexe D présente des exemples de parcours de dépressurisation dans un
diagramme de phase pour des fluides riches en CO .
Il convient que le concepteur prête attention aux points suivants:
— contrôler le débit de décompression rapide (opérations manuelles, orifice de restriction ou contrôle
automatique par étapes);
— choisir la contre-pression du collecteur de décompression rapide de sorte qu’elle soit supérieure au
point triple et au seuil de givre. Dans ce cas, il est recommandé de réaliser des études transitoires
appropriées pour mieux évaluer le système de décompression dans sa globalité;
— éviter les poches et minimiser les courbures dans les sections de tuyauterie en aval du dispositif de
décompression jusqu’au collecteur principal de torche ou d’évent;
— configurer le collecteur principal de torche ou d’évent de sorte à éviter toute obturation;
— utiliser un chauffage de tuyauterie par traçage;
— appliquer aux systèmes de décompression rapide l’intégralité de la pression assignée à l’amont, en
cas de risque d’obturation.
En ce qui concerne les critères de dépressurisation, le concepteur doit satisfaire aux exigences de
l’API STD 521 même dans le cas de fluides riches en CO ininflammables.
Il convient que la conception du système ESD envisage l’installation correcte de vannes
d’arrêt/d’isolement pour limiter les inventaires et donc minimiser la quantité de fluide piégé et les
répercussions potentielles des incidents.
Le risque de dommages dus à la décompression rapide des gaz sur les matériaux non métalliques
peuvent poser des limites à la vitesse de dépressurisation. Il est recommandé de faire figurer ce
scénario dans l’analyse des conséquences.
7 Configuration du système de torche et d’évent
7.1 Généralités
La conception des systèmes de torche et d’évent doit être conforme à l’API STD 521.
Il faut prendre en compte au moins les points suivants lors de la conception des systèmes de torche et
d’évent destinés aux fluides riches en CO :
— la composition des fluides riches en CO et le pouvoir calorifique inférieur minimal correspondant
(NHV);
— la combustibilité (torche);
— la dispersion des gaz en toute sécurité (évent);
— la formation de CO solide (voir Article 5);
— le profil de température pendant la dépressurisation (voir Article 6 et Article 8);
— le choix des matériaux métalliques et non métalliques (voir Article 8).
7.2 Choix du système
Le Tableau E.1 présente les différentes configurations possibles du système de torche et d’évent.
Si les fluides riches en CO contiennent de l’H S, il est recommandé de porter son choix sur le brûlage
2 2
à la torche plutôt que sur la dispersion par l’évent. Pour les systèmes de torche, il convient que la
conception tienne compte de la température de destruction de l’H S puisque les fluides à NHV bas ont
une température de flamme plus basse. Pour les systèmes d’évent, la conception doit garantir la bonne
dispersion de l’H S en raison du danger et des aspects de sécurité.
Les gaz brûlés à NHV bas ont une incidence sur la stabilité d’inflammation et peuvent éteindre la
flamme. Une solution peut consister à séparer le collecteur et le système d’évacuation entre les rejets à
NHV bas et à NHV haut.
Pour les fluides dont le NHV est inférieur à 7,5 MJ/Sm (200 BTU/SCF), ce qui correspond
approximativement à un mélange à 75 % (molaires) de CO et de méthane, il est recommandé d’utiliser
un évent ou une torche à brûleur à faible vitesse assistée par gaz. Il faut assurer un NHV minimal dans
les systèmes de torche pour permettre une bonne inflammation et une bonne combustion sur le nez de
torche, en mélangeant le gaz combustible auxiliaire provenant d’une source fiable aux fluides riches en
CO qui sont déchargés. Il convient que la capacité du gaz combustible auxiliaire soit prévue pour le cas
le plus défavorable.
3 3
Pour les fluides dont le NHV est supérieur à 7,5 MJ/Sm (200 BTU/SCF) et inférieur à 28,1 MJ/Sm
(800 BTU/SCF), l’utilisation de torches à brûleur à grande vitesse n’est pas recommandée. L’utilisation
8 © ISO 2016 – Tous droits réservés

d’un brûleur de ce type doit être soigneusement évaluée par rapport à celle d’un brûleur à faible vitesse.
La garantie du fabricant est nécessaire en cas d’utilisation d’un brûleur à grande vitesse.
Pour les torches à brûleur à grande vitesse, le NHV minimal typique du mélange de gaz à brûler s’élève
à 28,1 MJ/Sm (800 BTU/SCF). Cela correspond approximativement à un mélange à 25 % (molaires) de
CO et de méthane.
7.3 Configuration du système
7.3.1 Torche
Pour les unités qui traitent des fluides riches en CO , on peut envisager un autre système de torche pour
un NHV bas et/ou une température basse, en complément des systèmes typiques HP et LP.
L’inflammation des fluides riches en CO nécessite une source d’inflammation à haute énergie. On peut
obtenir de telles conditions en augmentant le nombre de flammes pilote par référence aux exigences
minimales figurant dans les recommandations des fabricants de pilotes selon l’ISO 25457.
Pour assurer la combustion, il faut porter une attention particulière à la vitesse au nez de torche. Il
est important de prendre en compte les aspects suivants: les torches à faible vitesse sont conçues et
opérées pour une vitesse à la sortie du nez inférieure à la vitesse maximale autorisée v définie par la
max
Formule (1) et limitée à 122 m/s (400 ft/s).
log v =+()NHVK12/K (1)
()
10 max
où
v est la vitesse maximale autorisée, exprimée en m/s;
max
K1 est une constante égale à 28,8;
K2 est une constante égale à 31,7;
NHV est le pouvoir calorifique inférieur, exprimé en MJ/Sm .
La méthode permettant de déterminer la vitesse maximale autorisée v est présentée dans la
max
Référence [13].
En principe, la vitesse maximale autorisée calculée à partir de la Formule (1) détermine le diamètre
équivalent de la zone du nez de torche. On peut contrer les effets des basses températures sur la
stabilité de la flamme en abaissant la vitesse ou en ajoutant du gaz auxiliaire. La conception du nez
de torche dépend des fournisseurs de nez de torche et il est recommandé d’apporter une preuve
expérimentale pour tous les scénarios de décharge critiques et/ou pour toutes les solutions n’ayant pas
fait leurs preuves. Il est recommandé de collaborer avec les fournisseurs de nez de torche dès le début
de la conception.
Il convient que le concepteur estime le bruit et les vibrations acoustiques induites.
La conception thermique de la torche doit être conforme à l’API STD 521 et suivre les recommandations
concernant le flux de rayonnement total admissible dans les zones de travail, sans bouclier thermique
dans l’unité.
Des simulations de dispersion sont nécessaires pour définir les aspects suivants de la conception:
longueur, hauteur, emplacement et orientation de la torche en fonction des directions dominantes du
vent. Il convient que le scénario de torche éteinte corresponde à l’un de ceux couverts par les études de
dispersion, en particulier compte tenu du fait que les rejets à basse température sont moins susceptibles
de s’enflammer.
7.3.2 Évent
Il faut estimer l’emplacement du nez de l’évent à partir des études de dispersion, des zones de sécurité
pratiques, du bruit, des vibrations acoustiques induites et du rayonnement thermique dans le cas d’un
scénario d’inflammation accidentelle.
Des simulations de dispersion, y compris l’évaluation du panache de CO , sont nécessaires pour définir
les aspects suivants de la conception: longueur, hauteur, emplacement et orientation de l’évent en
fonction des directions dominantes du vent. L’emplacement final des orifices de sortie doit assurer la
dispersion adéquate des décharges à faible débit.
De façon générale, il convient que le nez de l’évent soit incliné de 45° par rapport au plan horizontal, en
direction opposées aux zones de travail. On peut prévoir une protection contre la pluie.
Lors de la conception du système d’évent, il est recommandé de prendre en compte la formation de
CO solide due aux basses températures en aval des vannes de décharge/de décompression rapide. Si la
formation de CO solide est possible, il convient que la conception de l’évent minimise les possibilités de
blocage.
L’utilisation d’évents à grande vitesse est recommandée dans la mesure du possible afin de réduire
l’obturation potentielle par le CO ou l’hydrate et l’adhérence des solides, et d’améliorer la dispersion
des gaz.
8 Matériaux
8.1 Corrosion
8.1.1 Généralités
La corrosion interne peut représenter un risque significatif pour l’intégrité des tuyauteries et
équipements en acier au carbone en contact avec des fluides riches en CO en présence d’eau libre.
L’eau libre combinée à une pression partielle élevée de CO est susceptible de générer de fortes vitesses
de corrosion. Comme évoqué aux Annexes B et C, il est possible que l’eau soit moins susceptible de se
séparer de fluides gazeux riches en CO que du gaz naturel.
La présence d’H S combiné avec l’eau libre a des conséquences significatives sur la vitesse de corrosion.
La possibilité de pénétration de substances oxydantes en présence d’H S peut provoquer un dépôt de
soufre élémentaire à l’origine de vitesses plus importantes de corrosion.
Le choix des matériaux doit être conforme à l’ISO 21457. Il convient que les modèles physicochimiques
et les modèles de corrosion qui servent à évaluer la corrosion interne prennent en compte les fortes
teneurs en CO et les hautes pressions.
La tuyauterie, les accessoires et l’équipement utilisés avec des fluides contenant de l’H S doivent être
évalués d’après l’ISO 15156 (toutes les parties).
Il est recommandé d’estimer avec soin la corrosion interne des sections de tuyauterie et des autres
parties du système qui peuvent se trouver dans des conditions stagnantes (poches).
8.1.2 Contrôle de la corrosion interne par déshydratation
En général, les tuyauteries et équipements en acier au carbone n’exigent pas de protection contre la
corrosion interne dès lors que l’on évite la présence d’eau libre dans les fluides riches en CO , par le
biais d’une procédure de contrôle strict de leur teneur en eau. Il est recommandé de prendre en compte
cet élément en aval du système de déshydratation. Il est recommandé de prévoir la surveillance de la
teneur en eau dans le cadre de la conception et du fonctionnement des équipements concernés.
10 © ISO 2016 – Tous droits réservés

Les conditions d’arrêt et de fonctionnement dégradé doivent être prises en compte. Il peut s’agir de la
défaillance ou du fonctionnement hors spécifications du système de déshydratation, lorsqu’il s’agit de
spécifier les systèmes critiques ne tolérant aucune défaillance significative.
8.1.3 Alliages résistant à la corrosion (CRA)
La plupart des CRA conviennent aux applications de fluides riches en CO humides. Il est recommandé
d’utiliser des CRA massifs ou en couches minces (clad) pour prévenir la corrosion dans le système de
déshydratation lui-même et dans les dispositifs en amont. L’ISO 21457 donne des lignes directrices pour
choisir les CRA.
8.1.4 Produits chimiques protégeant de la corrosion interne
La stabilisation du pH et l’injection d’inhibiteurs de corrosion peuvent représenter un moyen efficace
de contrôler les vitesses de corrosion des fluides riches en CO en présence d’eau libre. Si l’on choisit
d’adopter cette approche, un programme de qualification est nécessaire pour s’assurer de l’efficacité de
la solution.
8.1.5 Revêtements organiques internes
L’utilisation d’un revêtement interne de protection contre la corrosion n’est pas recommandée en cas de
risque de dommages comme le décollement du matériau de la tuyauterie à cause de la RGD, de l’usure,
de l’installation ou de travaux. Des vitesses de corrosion importantes sont probables sur les sections
[14]
présentant des revêtements dégradés .
8.2 Rupture fragile
Si un fluide riche en CO est soumis à une dépressurisation, il peut rapidement se refroidir du fait
de l’effet Joule-Thomson. Les matériaux choisis doivent être adaptés à la température minimale de
conception. Cela s’applique à la fois au métal de base et aux soudures de raccordement.
Des matériaux dont les propriétés à basse température sont garanties doivent être utilisés pour les
appareils à pression, la tuyauterie, les vannes et les accessoires, y compris le corps et les parties internes
des soupap
...