EN 764-7:2002

SLOVENSKI STANDARD
01-november-2002
7ODþQDRSUHPDGHO9DUQRVWQLVLVWHPL]DQHRJUHYDQRWODþQRRSUHPR
Pressure equipment - Part 7: Safety systems for unfired pressure equipment
Druckgeräte - Teil 7: Sicherheitseinrichtungen für unbefeuerte Druckgeräte
Equipements sous pression - Partie 7: Systemes de sécurité pour équipements sous
pression non soumis a la flamme
Ta slovenski standard je istoveten z: EN 764-7:2002
ICS:
23.020.30
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 764-7
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2002
ICS 23.020.30
English version
Pressure equipment - Part 7: Safety systems for unfired
pressure equipment
Equipements sous pression - Partie 7: Systèmes de Druckgeräte - Teil 7: Sicherheitseinrichtungen für
sécurité ppour équipements sous pression non soumis à la unbefeuerte Druckgeräte
flamme
This European Standard was approved by CEN on 29 April 2002.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2002 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 764-7:2002 E
worldwide for CEN national Members.

Contents
page
Introduction .5
1 Scope .6
2 Normative references .7
3 Terms and definitions.7
4 Risk consideration.9
4.1 General.9
4.2 Identification of hazards.11
4.3 Solutions.12
5 Limiting devices and systems.12
5.1 General.12
5.2 Design .13
6 Pressure limitation.14
6.1 General.14
6.2 Safety valves, direct loaded and pilot operated .16
6.3 Bursting disc safety devices .17
6.4 Safety Valves & bursting disc safety devices in series or parallel.17
6.5 Controlled safety pressure relief systems (CSPRS) .18
6.6 Safety related measuring, control & regulation systems (SRMCR) .18
7 Hazard protection .20
7.1 Internal .20
7.2 External.20
7.3 Static electricity.20
8 Installation of pressure relieving devices .21
8.1 General.21
8.2 Safety valves or the main valve of a CSPRS.21
8.3 Installation of bursting disc safety devices .23
8.4 Safety valve and bursting disc safety devices in combination.23
8.5 Isolation of relieving safety systems .24
9 Indicators and alarms.25
9.1 General.25
9.2 Pressure indicators .25
9.3 Temperature indicators .26
9.4 Liquid level indicators .26
9.5 Signals and warning devices.26
10 Inspection and maintenance.27
Annex A (informative)  Sizing of multiple safety valves.29
(normative)
Annex B  Requirements for level limiters .31
B.1 General.31
B.2 Floating devices.31
B.3 Level electrode devices.31
B.4 Fault detection.32
Annex C (informative)  Selection of safety accessories for pressure limitation .33
(normative)
Annex D  Bursting disc safety devices downstream of safety valves .36
Annex E (informative) Scope of the standard.37
Annex ZA (informative) Clauses of this European Standard addressing essential requirements or other
provisions of EU Directives .38
Bibliography .39
Foreword
This document EN 764-7:2002 has been prepared by Technical Committee CEN/TC 54 “Unfired pressure vessels”,
the secretariat of which is held by BSI with support of Technical Committee CEN/TC 267 “Industrial piping”.
This European Standard shall be given the status of a national standard, either by publication of an identical text or
by endorsement, at the latest by November 2002, and conflicting national standards shall be withdrawn at the latest
by November 2002.
This document has been prepared under a mandate given to CEN by the European Commission (EC) and the
European Free Trade Association, and supports the essential safety requirements of the Pressure Equipment
Directive (PED) 97/23/EC.
For the relationship with the EU Directive(s) see the informative annex ZA which is an integral part of this
document.
This European Standard consists of the following parts:
Part 1: Definitions of pressure, temperature and volume.
Part 2: Quantities, symbols and units.
Part 3: Definition of parties involved.
Part 4: Establishment of technical delivery conditions for metallic materials.
Part 5: Inspection documentation of metallic materials and compliance with the material specification.
Part 6: Operating instructions.
Part 7: Safety systems for unfired pressure equipment.
Annexes A, C, E of this European Standard are informative. Annexes B and D are normative.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,
France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain,
Sweden, Switzerland and the United Kingdom.
Introduction
A safety system can be the ultimate limitation to protect pressure equipment from exceeding its allowable limits or a
means to prevent a potentially hazardous situation leading to injury. These limits consist of permissible pressure,
temperature, level, flow or a combination of these which were fixed at the design stage. Regular control and/or
monitoring devices which are not a necessary part of a safety systems are excluded from this standard since they
become active in advance of a safety system (see Figure 1).
It is essential to consider not only the pressure relieving device or safety related measurement, control and
regulation system (SRMCR) but the whole of the pressure relief system so as not to reduce the relieving capacity
or adversely effect the proper operation of the pressure relieving devices. Operating problems frequently occur in
pressure relief systems because of incorrect selection of the appropriate device or because a correctly selected
device was adversely affected by improper handling, incorrect installation or lack of maintenance.
In some cases it can be necessary to establish the basic details of the safety system before selecting the value of
the maximum allowable pressure PS for the equipment to be protected. Some safety systems need a usual margin
between the maximum operating pressure and their reseating pressure which has to be considered before
selecting PS.
NOTE The role of harmonized standards in supporting the essential safety requirements of European Directives is
described in the “Guide to the implementation of directives based on the New Approach and the Global Approach”. It can be
necessary for products to meet the requirements of more than one directive and it is the responsibility of the manufacturer to
ensure that these requirements are complied with. Annex ZA draws attention to the essential safety requirements of EU
Directive 97/23/EC “Pressure Equipment Directive” addressed by this standard. This standard also draws attention to subjects
which are not covered in detail but are relevant to safety systems.
Figure 1 — Response of regulating, monitoring and safety systems in relation to PS
1 Scope
This European Standard specifies the requirements for safety systems which protect a vessel, a system of vessels,
piping, accessories or assemblies from exceeding operating conditions.
It is also applicable to safety related indicators and alarms, signals and warning devices when used in safety
systems.
Equipment connected together by piping of adequate capacity, free from potential blockages and which does not
contain any valve that can isolate any part from the safety system may be considered as a single pressure system
when considering the requirements for overpressure protection.
Safety systems include the interconnections between the equipment to be protected and any discharge location.
This location can either be an outlet to atmosphere or the entry into a closed disposal system.
NOTE The scope of this standard and its relationship to the safety accessories and other protective devices described in
the Pressure Equipment Directive are shown in annex F.
2 Normative references
This European Standard incorporates, by dated or undated reference, provisions
...