EN 14359:2006

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Gas-loaded accumulators for fluid power applicationsAccumulateurs hydropneumatiques pour transmissions hydrauliquesHydrospeicher für HydraulikanwendungenTa slovenski standard je istoveten z:EN 14359:2006SIST EN 14359:2007en23.100.99Other fluid power system componentsICS:SLOVENSKI
STANDARDSIST EN 14359:200701-marec-2007

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14359October 2006ICS 17.040.30 English VersionGas-loaded accumulators for fluid power applicationsAccumulateurs hydropneumatiques pour transmissionshydrauliquesHydrospeicher für HydraulikanwendungenThis European Standard was approved by CEN on 18 September 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14359:2006: E

Categories of gas-loaded accumulators including reference to modules of conformity assessment.77 Annex B (informative) Summary of activities in respect to conformity assessment modules.78 Annex C (informative)
Examples of safety equipment configuration.79 Annex D (informative)
Manufacturer's declaration of conformity form.86 Annex E (informative)
Example of the application of the method of evaluating and interpreting fatigue test results carried out on complete accumulators.87 E.1 General.87 E.1.1 General.87 E.1.2 Consider a population of accumulators with the following characteristics:.87

Abacus.90 Annex G (informative)
Alternative relations for normal distributions.93 Annex H (informative)
Variation coefficients of equipment material.94 Annex I (informative)
Quality / severity condition of equipment / environment.95 I.1 Equipment quality: ki values.95 I.2 Severity conditions of environment: Ej values.95 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 97/23/EC.96 Bibliography.97

EN 13445-3:2002 but this European Standard is presumed to satisfy the essential requirements of the Pressure Equipment Directive 97/23/EC in its own right. NOTE If any matter of interpretation or doubt arises as to the meaning or effect of any normative part of this European Standard, or as to whether anything should be done or has been omitted to be done, in order that this European Standard should be complied with in full, the matter needs to be referred to the CEN/TC 54 Committee. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

(ISO 6506-1:2005) EN ISO 6506-2, Metallic materials — Brinell hardness test — Part 2: Verification and calibration of testing machines (ISO 6506-2:2005) EN ISO 6506-3, Metallic materials — Brinell hardness test — Part 3: Calibration of reference blocks (ISO 6506-3:2005) EN ISO 15614-1, Specification and qualification of welding procedures for metallic materials — Welding procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys (ISO 15614-1:2004) ISO 262, ISO general-purpose metric screw threads — Selected sizes for screws, bolts and nuts ISO 9110-1, Hydraulic fluid power — Measurement techniques — Part 1: General measurement principles ISO 9110-2, Hydraulic fluid power — Measurement techniques — Part 2: Measurement of average steady-state pressure in a closed conduit ISO 10771-1, Hydraulic fluid power — Fatigue pressure testing of metal pressure-containing envelopes — Part 1: Test method

Table 3.2-1 — Symbols, characteristics and units Symbol Characteristics Unit e Required thickness of the component, when obtained by direct calculation or the assumed thickness of the component, when obtained by non-direct calculation mm a ea Analysis thickness of the component = en-δe-δm-c mm a en Nominal thickness of the component, as specified on the manufacturing detail drawings mm a c Corrosion allowance mm a δe Absolute value of the negative tolerance taken from the material standard of the component mm a δm Possible thinning during manufacturing process of the component mm a N Number of pressure cycles
P0 Pre-charging pressure; the gas pressure in the accumulator when the hydraulic circuit is not under pressure (initial state) at a temperature of
(20 ± 5) °C MPa b P1 Minimum working pressure of the hydraulic circuit MPa b P2 Maximum working pressure of the hydraulic circuit MPa b P3 Set pressure of the safety accessory for the accumulator, if one is fitted MPa b PS Maximum allowable pressure, the pressure for which the accumulator has been designed and/or qualified by test MPa b PT Test pressure MPa b P2/P0 Allowable pressure ratio below which the accumulator type can be used
ReH Minimum upper yield strength MPa b Rm Minimum tensile strength MPa b Rm/t Minimum tensile strength at design temperature t °C MPa b Rp0,2 Minimum 0,2 % - proof strength MPa b Rp0,2/t Minimum 0,2 % - proof strength at design temperature t °C MPa b Rp1,0 Minimum 1,0 % - proof strength MPa b Rp1,0/t Minimum 1,0 % - proof strength at design temperature t °C MPa b TSmin
Minimum operating temperature of the hydraulic fluid or of the environment, whichever is lower or equal °C TSmax
Maximum operating temperature of the hydraulic fluid or of the environment, whichever is higher or equal °C V Internal volume of the gas chamber litre V0 Gas volume at pressure P0 litre V1, V2 Volumes occupied by the gas contained in the accumulator and the additional chambers, if any, at pressures P1 and P2 at their respective temperatures litre z Weld joint coefficient
a
The relationships between the defined thicknesses are shown in Figure 3.1. b
MPa for calculation purposes only, otherwise the unit should be bar (1 MPa = 10 bar).

enemceeaδδ
Key e required thickness en nominal thickness ea analysis thickness (en-δe-δm-c) c corrosion allowance δe
absolute value of the negative tolerance taken from the material standard of the component δm
possible thinning during manufacturing process of the component Figure 3.1 — Relationship of thickness definitions 4 Materials 4.1 Requirements for metallic materials The pressure containing envelope of gas-loaded accumulators shall be constructed of either:  harmonised materials used for the manufacture of unfired pressure vessels and meeting the requirements of EN 13445-2:2002;  materials other than those specified in EN 13445-2:2002 provided that they have been accepted by a particular material appraisal;  materials covered by a European approval for materials in accordance with Article 11 of Pressure Equipment Directive 97/23/EC. 4.2 Material certificates for components of the pressure containing envelope Components used in the manufacture of the pressure containing envelope of gas-loaded accumulators to category II, III and IV according to Annex II of the Pressure Equipment Directive 97/23/EC, shall be accompanied by an inspection document in accordance with EN 10204:2004 type 3.1 – see Annex B.

Figure 5.1 — Design process
5.4.2 Basic symbols, units and description Table 5.4-1 lists basic symbols and units. Further and modified notation is provided in the individual sections. Table 5.4-1 — Basic symbols and units Symbols Characteristics Units De Outside diameter of the shell mm Di Inside diameter of the shell mm es Required thickness of end to limit membrane stress in central part of shell mm ey Required thickness of knuckle to avoid axis-symmetric yielding mm f Nominal design stress at design temperature MPa a fa Nominal design stress at test temperature MPa a fshear Nominal design shear stress at design temperature = f x 0,8 MPa a ftest Nominal design stress for testing conditions MPa a h Internal height of dished end measured from cylindrical part mm r Inside radius of curvature of a knuckle mm R Inside spherical radius of central part of torispherical end mm a
MPa for calculation purposes only, otherwise the unit should be bar (1 MPa = 10 bar).

Normal Under test conditions Steels other than austenitic with
A < 30 % =2,4;1,5 minm/20p0,2/tRRf 1,05testp0,2/ttestRf= Austenitic steels with
30 % < A ≤≤≤≤ 35 % 1,5p1,0/tRf= 1,05testp1,0/ttestRf= Austenitic steels with
A > 35 % =3;1,2 min ;1,5maxm/tp1,0/tp1,0/tRRRf=2;1,05max testm/ttestp1,0/ttestRRf Cast steels =3;1,9 minm/20p0,2/tRRf 1,33testp0,2/ttestRf=
NOTE Only
is valid for fine-grained steels and heat-treated steels. 5.5 Design and calculation methods common to all accumulator types 5.5.1 General All applicable equations shall be used in order to demonstrate conformity with this European Standard. The maximum allowable pressure PS can be replaced by the test pressure PT when calculating for test conditions. 5.5.2 Specific definitions 5.5.2.1 Cylinder right circular cylinder 5.5.2.2 Torispherical end dished end, made up of a spherical cap, a toroidal knuckle and a cylindrical shell, the three components having common tangents where they meet 5.5.2.3 Klöpper-type torispherical end for which R/De = 1,0 and r/De = 0,1 5.5.2.4 Korbbogen-type torispherical end for which R/De = 0,8 and r/De = 0,154

DiDee Figure 5.2 — Geometry for cylindrical shells
The required wall thickness e is given by: SiSPzf2DPe−⋅⋅=
(5.5-1) or SeSPzf2 DPe+⋅⋅= (5.5-2)
For a given geometry:
iea4SDDezfP+⋅⋅= (5.5-3)
NOTE The requirements of Equations 5.5-2 and 5.5-3 are valid for e/De not greater than 0,16. 5.5.4 Dished ends under internal pressure 5.5.4.1 Hemispherical ends DiDee Figure 5.3 — Hemispherical end

S4iSPzfDPe−⋅⋅⋅= (5.5-4) or S4eSPzfDPe+⋅⋅⋅= (5.5-5)
Shell thickness may be increased at junctions with other parts such as cylindrical shells or the torus of a torispherical end. Increased thickness may also be necessary to provide reinforcement at isolated openings. The thickness of the cylinder up to the tangent line shall be kept at or above the minimum of the required cylinder wall thickness. 5.5.4.2 Torispherical ends 5.5.4.2.1 General
eDiDeRrh Figure 5.4 — Torispherical end
5.5.4.2.2 Conditions of applicability The following requirements are limited in application to ends for which all of the following conditions are met: a) r
≤ 0,2 Di b) r
≥ 0,06 Di c) r
≥ 2e d) e
≤ 0,08 De e) ea
≥ 0,005 De f) R
≤ De
(5.5-6)
()fDRPeiy2,075,0S⋅+⋅⋅= (5.5-7)
where
is found from the following equations: ()4,0;/eminRY= (5.5-8)
()YZ/1log10= (5.5-9)
i/DrX= (5.5-10)
()4902,61006,1YN⋅+−= (5.5-11)
For X = 0,06
()8873.12937,32124,23635,02306,0+−+−=ZZZN
For 0,06 < X < 0,1
()(){}1,006,006,01,025XX−+−=
For X = 0,1
()837,02943,10383,11833,0231,0+−+−=ZZZN
For 0,1 < X < 0,2
()(){}2,01,01,02,010XX−+−=
For X = 0,2
(){}5,0;5,8294,156,095,0max22,0YY−−=
(5.5-12) NOTE The above equations for
lead to an iterative calculation for which a computer procedure is recommended. 5.5.4.2.3 Special conditions for Klöpper-type ends R = De
r = 0,1 De
h = 0,193 5 De – 0,455 ea
0,10,001ea≤≤De
(5.5-13) 5.5.4.2.4 Special conditions for Korbogen-type ends R = 0,8 De
r = 0,154 De
h = 0,255 De – 0,635 ea
0,10,001aa≤≤De (5.5-14) 5.5.5 Isolated openings and nozzles in spherical shells and spherical centre areas of dished ends 5.5.5.1 Specific symbols and units Table 5.5-1 lists further specific symbols and units.

Table 5.5-1 — Specific symbols and units
Symbol Characteristics Unit a Distance taken along the average wall surface on the section where the reinforcement of an opening has to be calculated, between the opening centre and the external edge of a nozzle; if no nozzle is present, a is the distance between the centre and the internal edge of the opening mm Af Stress-loaded cross-sectional area effective as compensation mm2 Afb Af of a nozzle (b=branch) mm2 Afs Af of shell wall (main body) mm2 Afw Area of weld between nozzle and shell (only if outside the shell and nozzle shape, fillet weld) mm2 Ap Pressure-loaded area mm2 Aps Ap of shell (main body) mm2 Apb Ap of nozzle mm2 d Diameter (or maximum width) of opening, or inside diameter of nozzle mm deb Outside diameter of nozzle mm dib Inside diameter of nozzle mm ebk Required thickness of knuckle to avoid plastic buckling mm eb Required thickness of nozzle (or mean thickness within the length lbo or lbio) mm e´b Effective thickness of nozzle useful for reinforcement mm e´s Length of penetration of nozzle into shell wall for set-in nozzles with partial penetration mm ey Required thickness of knuckle to avoid axis-symmetric yielding mm fb f of nozzle MPa a fbk Nominal design stress for buckling equation MPa a fs f of shell material (main body) MPa a lb Length of nozzle extending outside the shell mm l´b Effective length of nozzle outside the shell, useful for reinforcement mm lbi Length of nozzle extending inside the shell mm l´bi Effective length of nozzle inside the shell, useful for reinforcement mm lbo Maximum length of nozzle outside the shell useful for reinforcement mm lbio Maximum length of nozzle inside the shell, useful for reinforcement mm l´s Effective length of shell, useful for opening reinforcement mm lso Maximum length of shell contributing to opening reinforcement taken on the mean radius of curvature of the shell wall mm ris Inside radius of curvature of the shell at the opening centre mm res Outside radius of curvature of the shell at the opening centre mm rms Mean radius of curvature of the shell at the opening centre mm a
MPa for calculation purposes only, otherwise the unit should be bar (1 MPa = 10 bar). 5.5.5.2 General All openings shall be isolated and circular with centrelines coaxial with the axis. For spherical shells and hemispherical or torispherical ends the following conditions shall be met. 0,6e;0,5is2≤≤⋅Ddrd (5.5-15)

Reinforcement is only permitted by increasing the wall thickness of the shell and/or a nozzle.
Nozzles may be ‘set-on’ or ‘set-in’ (see Figures 5.6 and 5.8). 5.5.5.3 Small openings If an isolated opening has a diameter d meeting the following condition: )(2s0,14seisred+⋅⋅⋅≤ (5.5-16) then the opening shall be considered a "small opening" and it needs no reinforcement. No further calculation is necessary. 5.5.5.4 Openings and nozzles used in accumulators
AfsApsrisrmsresesI'sdδ
debdibebApbAfsApsrisrmsresesI'sI'b < IboAfbIb_d Figure 5.5 — Reinforcement by wall thickness Figure 5.6— Reinforcement by Set-on nozzle (and wall thickness)

forged nozzle (and wall thickness) Figure 5.8 — Reinforcement by Set-in nozzle (and wall thickness)
5.5.5.5 Calculation procedure for openings in shells 5.5.5.5.1 Purpose The design method specified in this clause is applicable for a spherical shell or the spherical part of a torispherical end. The following conditions shall be satisfied:
)pbps(SS)0,5ob(fbS)0,5s()fwfs(AAPPfAPfAA+⋅≥⋅−⋅+⋅−⋅+ (5.5-17) )bsMIN(ff;fob= (5.5-18) For spherical shells: 2is2eisDeDr=−= (5.5-19)
For hemispherical or torispherical ends: Rr=is (5.5-20) For dished ends and spherical shells: isreal'rA+⋅+⋅⋅=s0,5s2is0,5sp (5.5-21)

)arcsin(ms/ra⋅= (5.5-22) where s0,5ismserr⋅+= (5.5-23) ms2ebrd⋅=δ (5.5-24) Moreover: for set-in nozzles: sssl'eAf⋅= (5.5-25) for set-on nozzles: )l'(eeAsbssf+⋅= (5.5-26) 5.5.5.5.2 Reinforcement by increased wall thickness of the shell The length of shell l´s, contributing to reinforcement of the opening, taken from the edge of the opening or from the external diameter of a nozzle and along the mean surface of the shell, shall not be greater than lso.
()ssoisss'2llree≤=⋅+⋅ (5.5-27) 5.5.5.5.3 Reinforcement by increased nozzle thickness The reinforcement of an opening can be obtained by increasing the wall thickness of the nozzle above the minimum thickness required in order to withstand the internal pressure (see 5.5.3). This possibility is independent of any reinforcement provided by increasing the wall thickness of the shell.
The length contributing to the reinforcement shall not be greater than lso for the shell and not more than lbo for the nozzle, with:
()boebbbldee≤−⋅ (5.5-28)
for set-in nozzles and forged nozzles (l´bi=0):
)sbib(bbe'l'l'e'Af++⋅= (5.5-29)
for set-on nozzles: bbbl'e'Af⋅= (5.5-30)

l´b = MIN (lbo; lb); l´bi = MIN (lbio; lbi); e´s is the length of penetration (full or part) of set-in nozzle into shell wall ( ≤es ); Apb = 0,5 · di · (l´b + es); Afs and Aps have already been defined in Table 5.5-1.

Key 1 external thread 2 internal thread
NOTE Thread geometry (60ο) shown as typical only – other thread types are permissible. Figure 5.9 — Geometry of threads

Symbol Characteristics Unit En max Maximum pitch diameter of internal thread mm En min Minimum pitch diameter of internal thread mm Ds min Minimum major diameter of external thread mm f sh Shear stress at calculation pressure MPa a Kn max Maximum minor diameter of internal thread mm Le Length of thread engagement at thread pitch diameter mm Lp Thread pitch mm a
MPa for calculation purposes only, otherwise the unit should be bar (1 MPa = 10 bar).
5.5.6.3 Shearing stress and length of thread engagement The shearing stress in threads shall be determined from the following equation: minne2S2ELPiDshf⋅⋅⋅= (5.5-31)
The length of thread engagement Le shall be determined from the following equation: minn2S2eEshfPiDL⋅⋅⋅≥ (5.5-32) 5.5.6.4 Thread compressive stress The compressive stress in the thread shall be determined from the following equation: )2max n2min s(epS2icompKDLLPD f−⋅⋅⋅= (5.5-33) The following shall be satisfied: f comp
≤
Rp0,2/t And the length of thread engagement Le shall be determined from the following equation: )2max n2min s(pS2ieKDfLPDL−⋅⋅⋅≥ (5.5-34)

Dc End plate connection port diameter mm Dp Nominal pitch diameter of body thread mm Du Thread relief diameter mm Et Thickness of shell at thread relief mm f b Flaring stress MPa a f comp Thread compressive stress MPa a Fe Applied force (moment per unit length on accumulator body) - Nmm/mm N Dm Mean body diameter at thread relief mm S Thickness of end plates mm Y End plate attachment factor
Y' End plate attachment factor
b Seal half section diameter ( for 'O' ring) mm m Seal coefficient
Go Seal groove outside diameter mm G Seal reaction diameter mm α Factor used for flaring stress calculation
β Factor used for flaring stress calculation mm-1 ν Poisson’s ratio
a
MPa for calculation purposes only, otherwise the unit should be bar (1 MPa = 10 bar).

Key 1 internally threaded body 2 end plate Figure 5.10 — End cap geometry – internally threaded body

This should be used in conjunction with the following equations. Table 5.6-2 — Screw threads Nominal pitch diameter of body thread (Dp) Thread pitch (Lp) ≤ 100 mm ≥ 1,5 mm 100 mm to 200 mm ≥ 2 mm 200 mm to 400 mm ≥ 3 mm > 400 mm ≥ 4 mm
NOTE For thread calculation see 5.5.6.

Y is dependent upon the value of the quotient Dc/Di. ∑=≤<−⋅=61i0,8ic0;1iiciDDDDAY (5.6-2) A1 =
0,999 034 2 A2 =
1,980 626 0 A3 =
-9,018 554 0 A4 =
18,632 830 0 A5 =
-19,497 590 0 A6 =
7,612 568 0 Alternatively, a value of 1,16 may be used for Y which will provide a conservative design. 5.6.1.5.2 Externally threaded body The thickness of flat end plates s for an externally th
...