CEN/TC 54 - Unfired pressure vessels

This Part 11 of this European Standard specifies requirements for unfired pressure vessels and their parts made of titanium and titanium alloys in addition to the general requirements for unfired pressure vessels under EN 13445:2014 Parts 1 to 5.
NOTE 1   Cast materials, HIP and additive manufacturing are not included in this version. Details regarding such materials will be subject to an amendment to or a revision of this European Standard.
NOTE 2   Materials in Groups 51.4 and 54 are not included in this version.

This Part of this document specifies the inspection and testing of individual and serially produced pressure vessels made of steels in accordance with EN 13445-2:2021.
Special provisions for cyclic operation are given in Annex G of this Part.
Special provisions for vessels or vessel parts working in the creep range are given in Annex F and Annex I of this Part.
NOTE   The responsibilities of parties involved in the conformity assessment procedures are given in Directive 2014/68/EU. Guidance on this can be found in CR 13445-7.

This document specifies the requirements for steel products used for unfired pressure vessels.
For some metallic materials other than steel, such as spheroidal graphite cast iron, aluminium, nickel, copper, titanium, requirements are or will be formulated in separate parts of this document.
For metallic materials which are not covered by a harmonized material standard and are not likely to be in near future, specific rules are given in this part or the above cited parts of this document.

This document specifies requirements for the manufacture of unfired pressure vessels and their parts, made of steels, including their connections to non-pressure parts. It specifies requirements for material traceability, manufacturing tolerances, welding requirements, requirements for permanent joints other than welding, production tests, forming requirements, heat treatment, repairs and finishing operations.

This document specifies requirements for the design, material, manufacturing and testing of cast iron pressure vessels and pressure vessel parts made from materials for which details are specified from the following material standards for specific grades which meet the criterion of an elongation after fracture less than or equal to 15 %:
-   EN 1561:2011, Founding - Grey cast irons;
-   EN 1563:2018, Founding - Spheroidal graphite cast irons;
-   EN 13835:2012, Founding - Austenitic cast irons.
The application of this document is limited to pressure equipment and pressure parts containing a fluid of group 2 (non-hazardous fluid) according to the European legislation for pressure equipment.

This Part of this document specifies requirements for the design of unfired pressure vessels covered by EN 13445-1:2019 and constructed of steels in accordance with EN 13445-2:2019.
EN 13445-5:2019, Annex C specifies requirements for the design of access and inspection openings, closing mechanisms and special locking elements.
NOTE This Part applies to design of vessels before putting into service. It may be used for in service calculation or analysis subject to appropriate adjustment.

This document defines the terms, definitions, quantities, symbols and units that are used throughout the EN 13445 series and gives general information on the design and manufacturing of vessels under this standard.
It also contains instructions on how to use the standard (Annex A) as well as an index which covers the whole standard (Annex B). This information is aimed to aid users of the EN 13445 series.
This document applies to unfired pressure vessels with a maximum allowable pressure greater than 0,5 bar gauge but may be used for vessels operating at lower pressures, including vacuum.
This document is not applicable to pressure vessels of the following types:
- vessels of riveted construction;
- vessels of lamellar cast iron or any other materials not included in Parts 2, 6, or 8 of the standard;
- multilayered, autofrettaged or pre-stressed vessels.
This document can be applied to the following pressure vessels, provided that account is taken of additional and/or alternative requirements resulting from the hazard analysis and from rules or instructions specific for:
- transportable vessels;
- items specifically designed for nuclear use;
- pressure vessels with a risk of overheating.
NOTE EN 14222 covers electrically fired boilers made from stainless steel and can be used as an example of additional requirements for such vessels.
Other European standards apply to industrial piping (EN 13480 series) and to water tube and shell boilers (EN 12952 series and EN 12953 series).

This Part 10 of this document specifies requirements for unfired pressure vessels and their parts made of nickel and nickel alloys (see 3.1) in addition to the general requirements for unfired pressure vessels under EN 13445-1:2019, EN 13445-2:2019, EN 13445-3:2019, EN 13445-4:2019 and EN 13445-5:2019.
NOTE Cast materials are not included in this version. Details regarding cast materials will be subject to an amendment to or a revision of this document.

This document specifies requirements for unfired pressure vessels and their parts made of aluminium and aluminium alloys in addition to the general requirements for unfired pressure vessels under EN 13445:2019 Parts 1 to 5. This document specifies unfired pressure vessels for loads up to 500 full cycles.
NOTE Cast materials are not included in this version. Details regarding cast materials will be subject to an amendment to or a revision of this document.

This document specifies requirements for the design, materials, manufacturing and testing of pressure vessels and pressure vessel parts intended for use with a maximum allowable pressure, PS, equal or less than:
- 100 bar when containing gases or liquids in group 1 or 2
- 1000 bar when containing liquids in group 2 only.
and shell wall thicknesses not exceeding 60 mm, which are constructed of ferritic or austenitic spheroidal graphite cast iron. The thickness limitation of the shell does not apply to thickness of flanges, reinforcements, bosses etc.
NOTE 1 Austenitic spheroidal graphite cast iron grades are principally used for high and low temperature applications and for their corrosion resistance properties.
NOTE 2 The allowable grades of spheroidal graphite cast iron are listed in Tables 5.1-1 and 5.1-2. Service conditions are given in Clause 4.
This document, EN 13445-6, does not include lamellar graphite cast iron grades for ferritic and austenitic grades with, with an elongation after fracture equal or less than 15 % which are explicitly excluded. Requirements for the use of cast irons with an elongation after fracture equal or less than 15 % are given in EN 15776.

This document is intended for the application of AT on metallic pressure equipment during controlled loading.
Therefore the overall aims of this document are:
-   to detect, locate and grade areas with evolving imperfections;
-   to provide the manufacturer the possibility to compare results of the first test with those of subsequent periodic inspections;
-   to determine the possibilities and limits of AE testing (AT) for pressure equipment;
-   to establish common basis for procedures to perform AT, taking into account the specific characteristics of the equipment under test;
-   to define the criteria, features and grades essential for evaluation of test results;
-   to suggest follow-ups to the test.

1.1   This European Standard specifies the requirements for materials, design, manufacture, testing inspection, safety equipment configuration and documentation (including instructions for first operation), for commonly-used types of gas-loaded accumulators and pressure vessels used to provide additional gas capacity for fluid power applications (see 1.2).
1.2   This European Standard applies to the following types of components, defined as the pressure-containing envelope of gas-loaded accumulators:
-   bladder type;
-   diaphragm type;
-   piston type;
-   transfer type;
-   pressure vessels used to provide additional gas capacity.
They consist of one or several parts joined together by a variety of mechanical means and by welding.
1.3   This European Standard applies to gas-loaded accumulators which operate with the following conditions:
-   subject to an internal gauge pressure greater than 0,5 bar;
-   working temperature not lower than -50 °C and not higher than +200 °C;
-   containing all liquids and gases as defined in the Pressure Equipment Directive 2014/68/EU,
see Note.
NOTE   When the accumulator contains Group 1 liquids or gases, consideration relating to risks other than those required by Pressure Equipment Directive 2014/68/EU are not covered by this European Standard and must be assessed separately.

This European Standard specifies terms and definitions to be used for pressure equipment and assemblies within the scope of European Directives on pressure equipment.
NOTE   It can be applied to other pressure equipment.

This document specifies the purpose, form and procedure of proof testing by pressure test of items of pressure equipment and assemblies.
It also specifies how to determine the value of the test pressure.

This European Standard specifies the requirements, under the regime of the EU Directive 97/23/EC on Pressure Equipment (PED), for the establishment of the technical delivery conditions in the form of:
-   harmonized European Standards for material;
-   European Approval for Materials (EAM);
-   Particular Material Appraisal (PMA)
for metallic materials for pressure equipment in all product forms. Welding consumables are not covered by this standard.
This European Standard was developed predominantly on the basis of steel, nickel and nickel-based materials. However, application to other materials is not restricted but should consider specific aspects relevant to the material concerned.

This European Standard specifies the provisions for inspection documentation of metallic materials, intended to be used under the regime of the PED, to comply with the Essential Safety Requirements 4.2 (b) and 4.3 of Annex I and to comply with the required material specification.
A simplified diagram of the routes for inspection documentation including compliance with the material specification is shown in Figure 1.

This Technical Report details the design, manufacturing, inspection and testing of a steel vessel submitted to pressure cycles, using the EN 13445 series for "Unfired pressure vessels", to guide the user of these standards in sequential decision making, together with some alternative choices.

This Technical Report presents an application of EN 13445 through an example of design and fabrication of an unfired pressure vessel. Every step is described as far as possible:
-   Material choice;
-   Design and calculation;
-   Fabrication;
-   Inspection and testing;
using the following part of EN 13445:
-   EN 13445-1:2009;
-   EN 13445-2:2009;
-   EN 13445-3:2009;
-   EN 13445-4:2009;
-   EN 13445-5:2009 .
As applicable, some choices for design or fabrication are made according to “the state of art” practice.
Some parts of EN 13445 are reproduced in order to show which requirements are relevant to the design and fabrication of the target vessel.

This part six of EN 764 is a Technical Report and as such is a generic document that identifies requirements for operating instructions which accompany the pressure equipment when it is placed on the market. It only provides general statements and thus does not claim to give presumption of conformity to the essential safety requirements of the Pressure Equipment Directive (PED).
Operating instructions contain the necessary safety information covering installation including assembling, putting into service and maintenance. For specific items of pressure equipment or assemblies, more detailed requirements on the content of operating instructions can be found in specific standards such as EN 13445 Unfired pressure vessels, EN 13480 Industrial piping, EN 12952 Water-tube boilers and auxiliary installations, or EN 12953 Shell boilers.

This European Standard specifies the basic quantities, symbols and units to be used for pressure equipment and assemblies addressed by the European Directive 97/23/EC.

This CEN Technical Report details the conformance of the EN 13445 series for "Unfired pressure vessels" to ISO 16528-1 "Boilers and pressure vessels - Part 1: Performance requirements".
This Technical Report applies to vessels of steel construction.
It is envisaged that future editions will include spheroidal graphite cast iron and aluminium vessels.

This European Standard specifies requirements for the design, manufacture and testing of closed expansion vessels with built in diaphragm, which will hereinafter be called "vessels", and
a)   whose diaphragm serves to separate water on the one hand and air / nitrogen on the other hand in heating/cooling systems or fresh water systems;
b)   which are manufactured singly or in series;
c)   which may consist partly or entirely of (cold) deep-drawn parts;
d)   whose parts may be joined by welding, clenching or flanges;
e)   whose size is not limited;
f)   whose maximum allowable pressure is greater than 0,5 bar, yet not exceeding 30 bar;
g)   whose upper wall thickness is limited to 12 mm for austenitic steels and 15 mm for ferritic steels;
h)   whose minimum operating temperature is not below -10 °C, whose maximum operating temperature is not above 70 °C.
NOTE   The maximum operating temperature of 70 °C is determined by the characteristics of the diaphragm materials. It may be higher, if suitability of diaphragm material is proven.
Whatever the temperature in the heating system, for the vessel operation the decisive factor is the maximum operating temperature of the diaphragm. It is the system designer's responsibility to prescribe measures to protect the diaphragm from unsuitable temperatures (e.g. connection to the coldest part of the system in a heating system, to the warmest in a refrigeration circuit; thermostatic monitoring of connection to vessel or intermediate vessel).
For cases where operating temperatures above 70 °C cannot be avoided the suitability of the diaphragm material is to be proven (see Clause 8).
When reference is made in this European Standard to EN 13445-1, -2, -3, -4 and -5 respectively, all relevant provisions in the concerned clauses of these standards need to apply.

TC - Modification to Scope
2013: Originator of XML version: first setup pilot of CCMC in 2012

Addition of a new normative Annex, for the requirement for peaking, based upon the requirements currently set out in EN 13445-4:2002 (clause 5.4.4).

UAP of 4 months (e-mail TC Secr. 00-12-12) (CC/001213)

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.

TC - New Figure 6.4.3.2-1

This Part of this European Standard applies to the design and manufacture of welded, simple unfired pressure vessels manufactured in series, with a single compartment, here-in-after referred to as vessels, the essential safety requirements of which are given in Annex G. It only applies to vessels that: a) include fabrication by welding, but some designs can entail the use of bolts; b) have a simple geometry enabling simple-to-use production procedures.

This Part of this European Standard is applicable to simple unfired steel pressure vessels, referred to as "vessel" in this standard, designed for air braking equipment and auxiliary pneumatic equipment for railway rolling stock.

This Part of this European Standard is applicable to simple unfired steel pressure vessels, referred to as "vessel" in this standard, designed for air braking equipment and auxiliary pneumatic equipment for railway rollingstock.

1.1 This part of this European Standard applies to the design and manufacture of simple unfired serially made pressure vessels, hereinafter referred to as vessels, designed for air breaking equipment and auxiliary systems for motor vehicles and their trailers, and which:    a)  include fabrication by welding;     b)  have a simple geometry enabling simple-to-use production procedures. This is achieved by either:    1) a cylindrical shell of circular cross section closed by outwardly dished and/or flat ends having the same axis of revolution as the shell; or:    2) two dished ends having the same axis of revolution.     c) have branches not larger in diameter than 0,5 of the diameter of the cylinder to which they are welded.  1.2 It applies to vessels which are intended to contain only compressed air, and which operate within the following constraints:   a) subjected to an internal pressure greater than 0,5 bar;    b) the parts and assemblies contributing to the strength of the vessel under pressure to be made either of non-alloy quality steel or of non-alloy aluminium or non-age hardening aluminium alloys;   c) maximum working pressure 30 bar. The product of that pressure and the capacity of the vessel (PS.V) is greater than 50 bar.litre and not exceeding 1500 bar.litre;   d) minimum working temperature - 50 øC and maximum working termperature not higher than 100 øC.   It does not apply to vessels specifically designed for nuclear use, to vessels specifically intended for installation in or the propulsion of ships and aircraft, or to fire extinguishers.  1.3 The essential safety requirements are given in annex G.

This document specifies general requirements for the application of additive manufacturing processes for pressure vessels and parts.
Separate Annexes of this document provide detailed requirements for specific additive manufacturing processes and materials.
This document is currently limited to metallic material applications. If a pressure part manufactured to this document is integrated into a pressure vessel, all parts of EN 13445 apply for this integration.

This Part of this European Standard specifies the inspection and testing of individual and serially produced pressure vessels made of steels in accordance with EN 13445-2:2014.
Special provisions for cyclic operation are given in Annex G of this Part.
Special provisions for vessels or vessel parts working in the creep range are given in Annex F and Annex I of this Part.
NOTE   The responsibilities of parties involved in the conformity assessment procedures are given in Directive 97/23/EC. Guidance on this can be found in CR 13445-7.

1.1   This document applies to the design and manufacture of welded, simple unfired pressure vessels manufactured in series, with a single or multiple compartment, here-in-after referred to as vessels.
It only applies to vessels that:
a)   include fabrication by welding, but some designs can entail the use of bolts;
b)   have a simple geometry enabling simple-to-use production procedures. This is achieved by either
1)   a cylindrical part of circular cross section closed by outwardly dished and/or flat ends which revolve around the same axis as the cylindrical part; or
2)   two outwardly dished ends revolving around the same axis.
1.2   It applies to vessels which are intended to contain air or nitrogen which are not intended to be fired and which operate within the following constraints:
a)   subjected to an internal gauge pressure greater than 0,5 bar;
b)   the parts and assemblies contributing to the strength of the vessel under pressure to be made either of non-alloy quality steel or of non-alloy aluminium or non-age hardening aluminium alloys;
NOTE   In this document, the use of "aluminium" covers non-alloy aluminium and aluminium alloys.
c)   the maximum working pressure is not greater than 30 bar. The product of the maximum working pressure and the capacity of the vessel (PS · V) is greater than 50 bar · l but does not exceed 10 000 bar · l. Below 50 bar · l use of this document is considered to fulfil the requirements of sound engineering practice;
d)   the minimum working temperature is not lower than −50 °C and maximum working temperature not higher than 300 °C for steel and 100 °C for aluminium or aluminium alloy vessels.
It does not apply to vessels specifically designed for nuclear use, to vessels specifically intended for installation in or the propulsion of ships and aircraft, or to fire extinguishers.
The document neither applies to transportation vessels nor to vessels which also contain substances other than air or nitrogen which could adversely affect their safety. For vessels to contain compressed air for braking systems of road vehicles and their trailers, see also EN 286-2. For vessels to contain compressed air for braking systems of rail mounted vehicles, see also EN 286-3 and EN 286-4.
1.3   It applies to the vessel proper, from the inlet connection to the outlet connection and to all other connections required for valves and fittings.
1.4   For the purposes of calculations required to be made in accordance with this document, dimensions are in millimetre, pressures are in bar (except otherwise specified), stresses are in newton per square millimetre and temperatures are in degree Celsius.

1.1   This document applies to the design and manufacture of simple unfired serially pressure vessels, herein after referred to as vessels, designed for air brake equipment and auxiliary systems for motor vehicles and their trailers, and which:
a)   include fabrication by welding;
b)   have a simple geometry enabling simple-to-use production procedures. This is achieved by either:
1)   a cylindrical shell of circular cross section closed by outwardly dished and/or flat ends having the same axis of revolution as the shell; or
2)   two dished ends having the same axis of revolution;
c)   have branches not larger in diameter than 0,5 of the diameter of the cylinder to which they are welded.
1.2   It applies to vessels intended to contain only compressed air, and which operate within the following constraints:
a)   subjected to an internal pressure greater than 0,5 bar;
b)   the parts and assemblies contributing to the strength of the vessel under pressure to be made either of non-alloy quality steel or of non-alloy aluminium or non-age hardening aluminium alloys;
c)   maximum working pressure 30 bar, the product of that pressure and the capacity of the vessel (PS ∙ V) is greater than 50 bar l and not exceeding 1 500 bar l;
d)   capacity not exceeding 150 l;
e)   minimum working temperature not lower than −50 °C and maximum working temperature not higher than 100 °C for aluminium vessels and not higher than 150 °C for steel vessels.
It does not apply to vessels specifically designed for nuclear use, to vessels specifically intended for installation in or the propulsion of ships and aircraft, or to fire extinguishers.

1.1   This document applies to the design and manufacture of simple unfired pressure vessels manufactured in series, for air brake equipment and auxiliary pneumatic equipment for railway rolling stock.
It defines three types of vessel A, B and C (see Table 1) corresponding to the current practice of European railway networks.
1.2   The vessels in this document are:
a)   made from a single shell;
b)   made from non-alloy steel;
c)   fabricated by welding;
d)   used at a maximum working pressure up to 15 bar;
e)   the product of the maximum working pressure (in bar) and the volume (in litre): 50 bar litres < PV ≤ 10 000 bar litres;
f)   made of a cylindrical part of circular cross-section called the shell with two outwardly dished torispherical ends, that is two dished ends with the same axis of rotation. This document therefore does not apply to vessels with one or two flat ends or those made up of several compartments;
g)   calculated with a design pressure P (see 5.1.4.1.2);
h)   designed for a working temperature of between −40 °C and +100 °C;
i)   fastened to vehicles:
1)   by straps for types A and B vessels,
2)   by welded brackets for types B and C vessels.
1.3   In normal service, a momentary overpressure of 10 % of PS, the maximum working pressure PS, is permitted.
1.4   This document applies to the vessel, from the inlet connection to the outlet connection and to all other connections and fittings belonging to the vessel.
1.5   This document gives the requirements to be met for the calculation, design, fabrication, inspection during fabrication and certification of the vessel, and fittings for assembly to the vehicle.
These requirements cannot be written in sufficient detail to ensure good workmanship or proper construction. Each manufacturer is therefore responsible for taking every necessary step to make sure that the quality of workmanship and construction is such as to ensure compliance with good engineering practice.
This document gives:
a)   in Annex B, recommendations for assembly to the vehicles;
b)   in Annex C, recommendations for the service surveillance of type A vessels;
c)   in Annex D, recommendations for the service surveillance of types B and C vessels.
The requirements of this document apply to vessels designed to be fitted to rail vehicles.
Table 1 - Definition of types of vessel
[table not reproduced]

Revision of annex C

Vessels on brackets- Revision of clause 16

This Part 10 of this European Standard specifies requirements for unfired pressure vessels and their parts made of nickel and nickel alloys (see 3.1) in addition to the general requirements for unfired pressure vessels under EN 13445-1:2014, EN 13445-2:2014, EN 13445-3:2014, EN 13445-4:2014 and EN 13445-5:2014.
NOTE   Cast materials are not included in this version. Details regarding cast materials will be subject to an amendment to or a revision of this European Standard.

New clause 18

1.1   This document is applicable to simple unfired aluminium alloy pressure vessels, referred to as "vessel" in this document, designed for air braking equipment and auxiliary pneumatic equipment for railway rolling stock (see 1.6).
1.2   The vessels to this document are:
a)   made from a single shell;
b)   made from aluminium alloy;
c)   fabricated by welding;
d)   used at a maximum working pressure of 10 bar;
e)   the product of the maximum working pressure (in bar) and the volume (in litre): 50 bar litres < PV ≤ 10 000 bar litres;
f)   made of a cylindrical part of circular cross section called the shell with two outwardly dished torispherical ends, that is two dished ends with the same axis of rotation. This document therefore does not apply to vessels with one or two flat ends or those made up of several compartments;
g)   calculated with a design pressure P (See 5.1.4.2);
h)   designed for a working temperature of between −50 °C and +100 °C [+65 °C for certain grades of aluminium alloy (see 4.1.1)];
i)   fastened to the vehicles by straps.
1.3   In normal service, a momentary overpressure of 1 bar of the maximum working pressure is permitted (10 % of PS).
1.4   This document applies to the vessel proper, from the inlet connection to the outlet connection and to all other connections and fittings belonging to the vessel.
1.5   This document gives the requirements to be met for the calculation, design, fabrication, inspection during fabrication and certification of the vessel, and fittings for assembly to the vehicle.
These requirements cannot be written in sufficient detail to ensure good workmanship or proper construction. Each manufacturer is therefore responsible for taking every necessary step to make sure that the quality of workmanship and construction is such as to ensure compliance with good engineering practice.
This document gives:
a)   in Annex B, recommendations for assembly to the vehicles;
b)   in Annex C, recommendations for the service surveillance of vessels.
1.6   The requirements of this document apply to vessels designed to be fitted to rail vehicles used on the main national networks, urban networks, underground railways, trams, private networks (regional railways, company railways, etc.).

Amends clause 9

Amends annex A

This Part 12 of EN 13445 series specifies requirements for unfired pressure vessels and their parts made of copper and copper alloys (see 5.2) in addition to the general requirements for unfired pressure vessels in EN 13445-1:2014 to EN 13445-5:2014.
NOTE 1 Cast materials are not included in this version. Details regarding cast materials will be subject to an amendment to or a revision of EN 13445 series.
NOTE 2 Soldered connections are presently not considered.

Revise clause 15

This Part of this European Standard specifies requirements for the design of unfired pressure vessels covered by EN 13445-1:2009 and constructed of steels in accordance with EN 13445-2:2009. EN 13445-5:2009, Annex C specifies requirements for the design of access and inspection openings, closing mechanisms and special locking elements. NOTE This Part applies to design of vessels before putting into service. It may be used for in service calculation or analysis subject to appropriate adjustment.

2007-06-13  Resolution 547 : CEN/TC 54 recommends to CMC to delete the work item for Creep in EN 13445-4:2002 (00054033), as the content has already been published in a previous amendment.

This European Standard specifies the requirements for materials, design, manufacture, testing inspection, safety systems and documentation (including instructions for first operation), for commonly-used types of gas-loaded accumulators and gas bottles for fluid power applications (see 1.2).
1.2   This European Standard applies to the following types of components, defined as the pressure-containing envelope of gas-loaded accumulators:
-   bladder type;
-   diaphragm type;
-   piston type;
-   transfer type;
-   gas bottles used to provide additional gas capacity.
They consist of one or several parts joined together by a variety of mechanical means and by welding.
1.3   This European Standard applies to gas-loaded accumulators which operate with the following conditions:
-   subject to an internal gauge pressure greater than 0,5 bar;
-   working temperature of not lower than 50 °C and not higher than +200 °C;
-   containing Group 2 liquids and gases as defined in the Pressure Equipment Directive 97/23/EC.
It does not apply to:
-   accumulators for use with dangerous fluids (see NOTE 1).
NOTE 1   Fluid power applications utilize non-dangerous fluids as categorized in ISO 6743-4 in addition to an inert gas (e.g. nitrogen) which is used as the pre-charging medium.
NOTE 2   There are no design limits to the volume of the accumulator.

WI abandoned - Content of this amendment exists in prA5.