CEN/TR 16395:2023

SLOVENSKI STANDARD
01-februar-2024
Infrastruktura za plin - Definicije tlaka, ki se uporabljajo v CEN/TC 234 - Smernice
Gas Infrastructure - CEN/TC 234 Pressure Definitions - Guideline Document
Gasinfrastruktur - CEN/TC 234 Druckdefinitionen - Leitliniendokument
Infrastructures gazières - Définitions des pressions du CEN/TC 234 - Lignes directrices
Ta slovenski standard je istoveten z: CEN/TR 16395:2023
ICS:
91.140.40 Sistemi za oskrbo s plinom Gas supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TR 16395
TECHNICAL REPORT
RAPPORT TECHNIQUE
November 2023
TECHNISCHER REPORT
ICS 91.140.40 Supersedes CEN/TR 16395:2012
English Version
Gas Infrastructure - CEN/TC 234 Pressure Definitions -
Guideline Document
Infrastructures gazières - Définitions des pressions du Gasinfrastruktur - CEN/TC 234 Druckdefinitionen -
CEN/TC 234 - Lignes directrices Leitliniendokument

This Technical Report was approved by CEN on 13 November 2023. It has been drawn up by the Technical Committee CEN/TC
234.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16395:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
3.1 Key pressure definitions used in CEN/TC 234 standards . 6
3.2 Derived pressure definitions used in CEN/TC 234 standards . 7
3.3 Commonly used pressure definitions in European product standards . 7
4 Explanation of Gas pressure definitions for gas transport and distribution systems . 8
4.1 General. 8
4.2 Pressure demarcation . 8
4.3 Operating conditions . 9
4.3.1 Normal operating conditions. 9
4.3.2 Gas pressure under incidental operating conditions . 9
4.4 Design pressure . 10
4.5 Test pressures . 10
4.6 Equipment in the scope of the European Pressure Equipment Directive . 10
5 Relationships between MOP, TOP and MIP and test pressures . 11
6 Pressure units in CEN/TC 234 European Standards . 11
Annex A (informative) Examples of relationships between pressure designations . 12
Annex B (informative) Industrial installations according to EN 15001 [16], [18] . 14
Bibliography . 15

European foreword
This document (CEN/TR 16395:2023) has been prepared by Technical Committee CEN/TC 234 “Gas
Infrastructure”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes CEN/TR 16395:2012.
In comparison with the previous edition, the following modifications have been made:
— updating the scope for the alignment with the current scope of CEN/TC 234;
— updating of titles of the documents in the bibliography;
— addition of new documents published by CEN/TC 234 in the bibliography;
— updating of the reference to PED in term 3.3.1;
— introduction of a new clause on pressure units in CEN/TC 234 European Standards;
— editorial alignment of the wording to the current CEN drafting rules for Technical Reports.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
Introduction
Background
The standards issued by CEN/TC 234 “Gas Infrastructure” contain a large number of definitions used for
the design, testing and operation of the different parts of the gas infrastructure.
This document clarifies the CEN/TC 234 concept behind the pressure definitions and advises how to use
the pressure definitions correctly and consistently. In order to further that goal an inventory of existing
definitions is made and the primary definitions are identified.
This document also gives guidance for the selection of components falling into the scope of the European
Pressure Equipment Directive (PED) [1] and used in the gas infrastructure.
Apart from the issue of the consistency of the pressure definition in the standards there is also the issue
of the pressure rating of equipment and systems. Other classifications (e.g. PN or class) do not necessarily
completely coincide with the classification as defined in the CEN/TC 234 standards.
Operating pressures levels of the gas infrastructure are different from one country to another in EU,
because of many different factors such as history of gas systems, technologies and materials used or
technical constraints.
When starting drafting the functional standards on gas infrastructure, CEN/TC 234 recognized various
pressure levels and ranges in the European member countries, which are to some extent laid down in
national laws.
To form a consensus for the standardization work, all pressure levels used in Europe have been brought
together and classified in ranges. This subdivision in pressure levels also permits the manufacturers of
components to focus on a limited number of designs in order to reduce the costs.
Concept of pressure conditions
On one hand three different sets of pressure conditions are to be considered:
— conditions during testing and commissioning (P );
— conditions during exceptional operating circumstances (P );
— conditions during normal operation (P ).
where:
P > P > P
1 2 3
The maximum pressure levels related to these conditions are the topic of the primary definitions.
On the other hand two other pressure conditions are used for specifying the system:
— pressure on which design calculations are based (p );
A
— pressure rating of the system (p ).
B
where
p > p .
A B
The relationship between p and P or P is not uniform in the different CEN/TC 234 standards. This
A 2 3
situation is confusing and undesirable. The recommended practice is stated in 4.4 and 4.5.
Piping versus pressure regulating installations
Only two out of the three aforementioned conditions apply when specifying piping:
— conditions during testing and commissioning;
— operating conditions.
Normally for piping no distinction is made between normal operating conditions and exceptional
operating conditions, as piping is a passive component. However, in gas infrastructure piping and
pressure regulating installations both are present. This necessitates identification of the “normal
operating conditions” and “exceptional operating conditions” of the pressure regulating installations and
the “operating conditions” of the piping.
1 Scope
This document gives explanation on the pressure definitions and pressure units used by the gas network
operators with regard to the standards of CEN/TC 234 “Gas Infrastructure”.
The European Standards of CEN/TC 234 cover the field of gas pipeline infrastructure for gaseous energy
carriers and blends thereof from the input into the on-shore transmission network up to the inlet
connection of gas appliances; This includes related functional requirements for injection, transmission,
compression, pressure control, storage, blending, gas treatment, odorisation, distribution, measuring,
and associated installation pipework, as well as related requirements such as safety, gas quality,
sustainability, environment and emissions.
Within the scope of CEN/TC 234, gaseous energy carriers and blends describe gases which are in the
gaseous state when conveyed in the gas pipeline infrastructure such as hydrogen, hydrogen rich, and
methane rich gases, dimethyl ether (DME) and propane and butanes used for combustion and/or as
feedstock, excluding steam and compressed air.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1 Key pressure definitions used in CEN/TC 234 standards
3.1.1
design pressure
DP
pressure on which design calculations are based
Note 1 to entry: A system designed for a design pressure DP can comprise components designed for a different
maximum allowable pressure (PS).
3.1.2
maximum operating pressure
MOP
maximum pressure at which a system can be operated continuously under normal operating conditions
Note 1 to entry: Normal operating conditions are: no fault in any device or stream.
Note 2 to entry: The set point of the regulator does not exceed MOP.
3.1.3
maximum incidental pressure
MIP
maximum pressure which a system can experience during a short time, limited by the safety devices
3.2 Derived pressure definitions used in CEN/TC 234 standards
3.2.1
operating pressure
OP
nominal pressure on which the system is operated
3.2.2
temporary operating pressure
TOP
pressure at which a system can be operated temporarily under control of regulating devices
3.2.3
test pressure
TP
pressure at which pressure tests are conducted
3.2.4
strength test pressure
STP
pressure applied to a system during strength testing
3.2.5
tightness test pressure
TTP
pressure applied to a system during tightness testing
3.2.6
combined test pressure
CTP
pressure applied to a system during combined testing, i.e. tightness and strength testing
3.3 Commonly used pressure definitions in European product standards
3.3.1
maximum allowable pressure
PS
maximum pressure for which the equipment is designed, as specified by the manufacturer
Note 1 to entry: Definition and requirements are according to Directive 2014/68/EU (Pressure Equipment
Directive – PED) [1].
3.3.2
nominal pressure
PN xx
alphanumeric designation used for reference purposes related to a combination of mechanical and
dimensional characteristics of a flanged or welded component of a pipework system, comprising the
letters PN followed by a dimensionless number
Note 1 to entry: The number following the letters PN does not represent a measurable value and is not used for
calculation purposes except where specified in the relevant standard.
Note 2 to entry: The designation PN is not meaningful unless it is related to the relevant component standard
number.
Note 3 to entry: It is intended that all components with the same PN and DN designations have the same mating
dimensions for compatible flange types.
[SOURCE: EN 1333 [2], modified]
3.3.3
class xxx
alphanumeric designation used for reference purposes related to a combination of mechanical and
dimensional characteristics of a flanged or welded component of a pipework system, comprising the
word “Class” followed by a dimensionless whole number
Note 1 to entry: The number following the word “Class” does not represent a measurable value and is not used for
calculation purposes except where specified in the relevant standard.
Note 2 to entry: The designation class is not meaningful unless it is related to the relevant component standard
number.
Note 3 to entry: It is intended that all components with the same class and NPS designations have the same mating
dimensions for compatible flange types.
[SOURCE: EN 1759-1 [3]]
4 Explanation of Gas pressure definitions for gas transport and distribution
systems
4.1 General
The pressure levels in the system MOP, TOP and MIP are chosen by the network operat
...