CEN/TR 14585-3:2017

Corrugated metal hose assemblies for pressure applications - Part 3: Design method

This Technical Report provides guidance on the design of corrugated metal hose assemblies for pressure applications, i.e. maximum allowable pressure PS greater than 0,5 bar. Allowable stresses are consistent with the requirements of the Pressure Equipment Directive 2014/68/EU.

Gewellte Metallschlauchleitungen für Druckanwendungen - Teil 3: Auslegungsverfahren

Tuyauteries métalliques flexibles onduleuses pour applications sous pression - Partie 3: Méthode de conception

Le présent Rapport Technique fournit des lignes directrices pour la conception de tuyauteries métalliques flexibles onduleuses pour applications sous pression, c'est-à-dire la pression maximale admissible PS supérieure à 0,5 bar. Les contraintes admissibles sont cohérentes avec les exigences de la Directive 2014/68/UE «Équipements sous pression».

Valoviti kovinski cevni sestavi v tlačnih cevovodih - 3. del: Metode načrtovanja

To tehnično poročilo podaja smernice za načrtovanje valovitih kovinskih cevnih sestavov v tlačnih cevovodih, pri katerih je največji dovoljeni tlak PS večji od 0,5 bara. Dopustne obremenitve so v skladu z zahtevami direktive o tlačni opremi 2014/68/EU.

General Information

• Status: Withdrawn
• Publication Date: 24-Oct-2017
• Withdrawal Date: 13-Apr-2025
• ICS: 23.040.70 - Hoses and hose assemblies
• Technical Committee: CEN/TC 342 - Metal hoses, hose assemblies, bellows and expansion joints
• Drafting Committee: CEN/TC 342/WG 1 - Hose assemblies and fittings
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Start Date: 09-Oct-2024
• Completion Date: 14-Apr-2025
• Ref Project: SIST-TP CEN/TR 14585-3:2018 - Corrugated metal hose assemblies for pressure applications - Part 3: Design methods

Relations

• Replaced By: EN 14585:2024 - Corrugated metal hose assemblies for pressure applications
• Effective Date: 22-Aug-2018

Standards Content (Sample)

SLOVENSKI STANDARD
01-februar-2018
9DORYLWLNRYLQVNLFHYQLVHVWDYLYWODþQLKFHYRYRGLKGHO0HWRGHQDþUWRYDQMD
Corrugated metal hose assemblies for pressure applications - Part 3: Design methods
Gewellte Metallschlauchleitungen für Druckanwendungen - Teil 3: Auslegungsverfahren
Tuyauteries métalliques flexibles onduleuses pour applications sous pression - Partie 3:
Méthode de conception
Ta slovenski standard je istoveten z: CEN/TR 14585-3:2017
ICS:
23.040.10 Železne in jeklene cevi Iron and steel pipes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TR 14585-3
TECHNICAL REPORT
RAPPORT TECHNIQUE
October 2017
TECHNISCHER BERICHT
ICS 23.040.70
English Version
Corrugated metal hose assemblies for pressure
applications - Part 3: Design method
Tuyauteries métalliques flexibles onduleuses pour Gewellte Metallschlauchleitungen für
applications sous pression - Partie 3: Méthode de Druckanwendungen - Teil 3: Auslegungsverfahren
conception
This Technical Report was approved by CEN on 25 September 2017. It has been drawn up by the Technical Committee CEN/TC
342.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 14585-3:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and abbreviations . 7
5 Materials . 10
5.1 General requirements . 10
5.2 Suitable materials . 10
5.3 Other materials . 13
5.4 Corrosion . 13
5.5 Low temperature application . 13
5.6 Material documentation . 15
6 Design methods . 15
6.1 General . 15
6.2 Basic design criteria . 16
6.2.1 Design conditions . 16
6.2.2 Temperatures . 16
6.2.3 Additional loadings . 16
6.2.4 Structural conditions . 17
6.2.5 Dimensions . 17
6.3 Design on the basis of nominal pressures PN . 19
6.4 Allowable stresses . 19
7 Calculation design method . 20
7.1 General . 20
7.2 Corrugated metal hose . 21
7.2.1 Scope . 21
7.2.2 General factors . 22
7.2.3 Limiting conditions. 24
7.2.4 Pressure capacity of the corrugated metal hose braided or unbraided . 26
7.3 Braid . 28
7.3.1 Scope . 28
7.3.2 General factors . 28
7.3.3 Limiting design conditions . 30
7.3.4 Pressure capacity of the braid . 31
7.4 Metal hose assembly . 31
7.4.1 General . 31
7.4.2 Burst pressure of the corrugated hose . 32
7.4.3 Burst pressure of the braid . 33
7.4.4 Burst pressure of the metal hose assembly . 33
7.5 Flanges and other end fittings . 34
Annex A (informative) Calculation coefficients C , C , C . 35
p f d
A.1 Graphs of coefficients . 35
A.2 Polynomial approximation of the coefficients . 38
A.2.1 Coefficients C . 38
p
A.2.2 Coefficients C . 39
f
A.2.3 Coefficients C . 39
d
A.2.4 Intermediate values . 40
Annex B (informative) Main information to be supplied to the hose manufacturer. 41
B.1 Main design conditions . 41
B.2 Additional information/requirements dependent on application . 41
Bibliography . 42

European foreword
This document (CEN/TR 14585-3:2017) has been prepared by Technical Committee
CEN/TC 342 “Metal hose, hose assemblies, bellows and expansion joints”, the secretariat of which is
held by SNV.
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.
Introduction
Technical Committee CEN/TC 342 “Metal hose, hose assemblies, bellows and expansion joints” is
carrying out a revision of EN 14585-1:2006 and CEN/TR 14585-2:2006 to include calculation methods
for the combined structure of hose and braid for:
— pressure resistance;
— fatigue life;
— allowable displacements.
The selection of materials for corrosive environments and the calculation of fluid pressure drops are
also being included.
It is appreciated that these studies are ambitious and will involve much new analyses so that this
revision will take some time.
Whilst continuing to work on this revision, CEN/TC 342 decided that the key aspects of the calculation
method should be circulated as an informative Technical Report CEN/TR 14585-3, which is limited to
the pressure resistance of the combined structure of hose and braid. This approach will enable
manufacturers and Notified Bodies to use and gain experience of the calculation method and any
feedback can be taken into account in the revision of EN 14585, harmonized to the Pressure Equipment
Directive 2014/68/EU.
1 Scope
This Technical Report provides guidance on the design of corrugated metal hose assemblies for
pressure applications, i.e. maximum allowable pressure PS greater than 0,5 bar. Allowable stresses are
consistent with the requirements of the Pressure Equipment Directive 2014/68/EU.
2 Normative references
Not applicable.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 7369 and the following
apply.
3.1
metal hose assembly
assembly of a corrugated metal hose with its end fittings
Note 1 to entry: In the context of Pressure Equipment Directive [1], a metal hose assembly is a component of
piping and not a PED assembly.
3.2
maximum allowable pressure PS
maximum pressure for which the metal hose assembly is designed
3.3
maximum/minimum allowable temperature TS
maximum and minimum temperature for which the metal hose assembly is designed
3.4
nominal pressure PN
dimensionless alphanumerical designation which is a convenient rounded number commonly used for
reference purposes of piping components and stock parts; for this Technical Report PN represents the
maximum allowable pressure at 20 °C as specified by the metal hose assembly manufacturer
3.5
test pressure PT
pressure at which the pressure metal hose assembly is pressure tested (normally at ambient
temperature)
3.6
main pressure bearing parts
parts, such as corrugated metal hose, braid, pipe ends, the failure of which may result in a sudden
discharge of pressure energy
3.7
pressure bearing parts
parts, such as swivel nuts, flanges, threaded fittings, that are not main pressure bearing parts defined in
3.6 and the failure of which may not lead to a sudden discharge of pressure energy
3.8
attachments to pressure parts
parts, such as ferrules, that are directly welded to parts defined in 3.6 or 3.7
3.9
other parts
parts, such as external protection, anti-kink device, braid protecting spiral, which are not parts
according to 3.6 to 3.8
3.10
equipment manufacturer
natural or legal person responsible for the values of the parameters PS and TS
Note 1 to entry: This may be the manufacturer or planner of the piping for which the metal hose assembly is
designed.
3.11
hose manufacturer
natural or legal person responsible for the design and the manufacturing of the corrugated metal hose
and/or the metal hose assembly
3.12
hydraulic forming (longitudinal welded)
corrugating a tube by pressurizing the inside against external tooling which allows this corrugated tube
to be axially shortened during the process
3.13
roll forming (longitudinal welded)
corrugating a tube by rolling from the outside to the inside and allowing or forcing this corrugated tube
to be axially shortened during the process
3.14
helical crest welded (resistance welded)
profiling a strip, rolling it over helically and finally welding the overlaps
3.15
strand
group of parallel wires used for plain braid or wires woven together to form a braided strand
3.16
braided braid
braid that is manufactured from previously braided strands
4 Symbols and abbreviations
For the purposes of this document, the symbols listed in Table 1 apply.
Table 1 — Symbols
Symbol Description Unit
A elongation at rupture according to EN ISO 6892–1 %
A cross sectional metal area of one corrugation; see Formula (3a) and 3b) mm
c
A hose effective area; see Formula (5) mm
e
a Braid wire cross section; see Formula (29) mm
w
b width of corrugation crest; see Figures 2 a) and 2 b) mm
c
Symbol Description Unit
b nominal width of material (strip) according to EN ISO 9445-1 mm
n
b width of corrugation root; see Figures 2 a) and 2 b) mm
r
b width of a strand; see Figure 4 mm
s
C , C factors used to determine the calculation coefficients C , C , C ; see —
1 2 p f d
Formulae (6) and (7)
CB braid coverage; see Formula (38) —
C , C , C calculation coefficients (see Annex A) —
p f d
stacking factor for crossing braid wires and strands; see Formula (26) —
c
st
D inside diameter of the corrugated metal hose; see Figures 2 a) and 2 b) mm
i
D mean diameter of the corrugated metal hose; see Formula (8) mm
m
D outside diameter of the corrugated metal hose; see Formulae (9a) and mm
o
(9b)
d diameter of the braid wire; see Figure 4 mm
w
d mean diameter of a braid layer; see Formula (30) mm
B
E modulus of elasticity of hose material at room temperature N/mm (MPa)
E modulus of elasticity of hose material at design temperature N/mm (MPa)
t
e nominal thickness of hose material; see Figures 2 a) and 2 b) mm
e nominal thickness of one ply mm
p
e* equivalent wall thickness, corrected for thinning during forming; see mm
Formula (11)
e * equivalent thickness of one ply with thinning correction; see mm
p
Formulae (10a) and (10b)
F force due to pressure effect (pressure thrust); see Formula (12) N
p
f allowable general membrane stress at design temperature; see Table 7 N/mm (MPa)

f allowable general membrane stress at test conditions; see Table 7 N/mm (MPa)
T
G degree of load; see 5.5 and Formula (1) —
σ
hs thickness of a strand; see Formula (27) mm
K axial spring rate of one corrugation; see Formula (21) N/mm
ax(1)
K forming factor; see Formulae (18) and (19) —
f
k reduction factor for circumferential stress due to braid; see Formula (32) —
Θ
k derating factor for the pressure at operating temperature t ; see 6.3 —
p,t
l axial pitch of the braid; see Figure 4 and Formula (24) mm
B
l active corrugated length of a metal hose mm
c
n number of plies of a corrugated metal hose —
p
n number of braid strands —
s
Symbol Description Unit
n number of wires in one braid strand —
w
P pressure resulting in an initial remaining (plastic) elongation of 1 %; see N/mm (MPa)
1,0
Formula (22)
P primary meridional bending stress N/mm (MPa)
m,b
P primary meridional membrane stress N/mm (MPa)
m,m
PΘ primary circumferential stress N/mm (MPa)
a maximum allowable pressure N/mm (MPa)
PS
PT test pressure bar
P maximum allowable pressure at operating temperature t; see bar
t, max
Formula (2)
q corrugation length; see Figures 2 a) and 2 b) mm
R to R bend radii of hose assemblies; see Table 5 mm
1 4
R minimum specified value of upper yield strength at design temperature N/mm (MPa)
eH, t
R minimum specified value of tensile strength at design temperature N/mm (MPa)
m, t
R minimum specified value of tensile strength at room temperature N/mm (MPa)
m, 20
R minimum specified value of 0,2 % proof strength at design temperature N/mm (MPa)
p 0,2, t
R minimum specified value of 1 % proof strength at design temperature N/mm (MPa)
p 1,0, t
r mean radius of torus at crest and root of U-shaped corrugations; see mm
m
Figures 2 a) and 2 b) and Formulae (4a) and (4b)
t operating temperature °C
t nominal thickness of the material (strip) mm
n
w corrugation height, see Figures 2 a) and 2 b) and Formula (13) mm
α initial braid angle; see Figure 4 and Formula (25) degree or
radian
β initial side wall angle of the corrugation; see Figure 3 and Formula (14) degree
Δl elastic hose elongation due to pressure; see Formula (20) mm
el
Δl plastic hose elongation due to pressure; see Formula (46) mm
pl
η load carrying efficiency of braid layer; see 7.3.2.4 -
λ relative plastic elongation; see Formula (46) -
ν value of Poisson's ratio for stainless steel of 0,3 -
σ (P) stress depending on P N/mm (MPa)
σ longitudinal stress in the braid wire; see Formula (39) N/mm (MPa)
w
Subscripts: o outside
0 initial p ply
B braid pl plastic
H hose r root
Symbol Description Unit
t test condition t temperature
b bending or burst condition w wire
c corrugation or crest Δ difference
el elastic λ relative elongation
i inside or running index Θ circumferential
m membrane, meridional or mean Σ sum
n number of or upper summation index
a 2
All pressures for calculation purpose are in N/mm (MPa).

5 Materials
5.1 General requirements
Materials for the manufacture of hose assemblies including filler metal should be selected on the basis
of their suitability for fabrication, e.g. forming, joining, and for the conditions under which they will be
used.
When combining different materials, special care should be taken regarding compatibility with each
other.
5.2 Suitable materials
Materials suitable for hoses assemblies are given as follows:
a) materials suitable for corrugated metal hoses and their temperature limits are given in Table 2;
b) materials suitable for braid, fittings, and additional parts are given in Table 3.
Table 2 — Materials for corrugated metal hoses and their temperature limits
Material Temperature °C
Document
Type Number Steel name Minimum Maximum
a
1.4306 X2CrNi19–11 550
– 273
a
1.4401 X5CrNiMo17–12–2 550
– 196
a
1.4404 X2CrNiMo17–12–2 550
– 273
stainless
a
1.4435 X2CrNiMo18–14–3 550
– 273
austenitic EN 10028–7
a
1.4539 X1NiCrMoCu25–20–5 550
– 196
steels
a
1.4541 X6CrNiTi18–10 550
– 273
a
1.4547 X1CrNiMoCuN20–18–7 500
– 196
a
1.4571 X6CrNiMoTi17–12–2 550
– 273
X10NiCrAlTi32–21 EN 14917, B (2.1)
heat resistant
1.4876 – 196
austenitic steels b
X10NiCrAlTi32–21 (H) EN 14917, B (2.2)
Material Temperature °C
Document
Type Number Steel name Minimum Maximum
2.4360 NICu30Fe – 196 425 EN 14917, B (3)
2.4610 NiMo16Cr16Ti – 196 400 EAM-0526–28
EAM-0526–43–1,
– 10 450
EAM-0526–43–2
2.4816 NiCr15Fe
EN 14917:2009+A1:
b
(– 273)
Nickel (900)
2012, Annex J
alloys
2.4819 NiMo16Cr15W – 196 400 EAM-0526–18
– 196 450 EAM-0526–40
2.4856 NiCr22Mo9Nb
EN 14917:2009+A1:
b
(– 273)
(900)
2012, Annex J
2.4858 NiCr21Mo – 10 540 EN 14917, B (4)
Copper CW024A Cu-DHP (R200) - 180 250
CW452K CuSn6 (R350) - 250 500
c
EN 1652
Copper alloy CW503L CuZn20 (R270) - 200 300
CW508L CuZn37 (R300) - 200 500
a
Minimum temperature in accordance with EN 13445–2 / Annex B or EN 13480–2 / Annex B.
b
Special care should be exercised due to the risk of embrittlement when using the materials at elevated
temperatures above 550 °C.
c
Copper and copper alloys for general purpose (not harmonized to PED); Particular Material Appraisals
(PMA) are necessary for applications within the scope of the PED.

Table 3 — Materials for braid, fittings, ferrules, and additional parts
Component Material No Document
Pressure parts
1.4301, 1.4306, 1.4401, 1.4404, 1.4541, 1.4571 EN 10088–3
1.4876, 2.4360, 2.4816, 2.4819, 2.4856, 2.4858 Table 2
Braid
a
Cu-based material: CW450K, CW452K, CW508L
EN 12166
forged EN 10222–2 and −3
Carbon steel
flat products EN 10028–2
Fixed flange,
EN 10222–5,
Weld collar,
1.4301, 1.4306, 1.4401, 1.4404, 1.4541, 1.4571
EN 10028–7
b
Floating flange
1.4876, 2.4360, 2.4816, 2.4819, 2.4856, 2.4858 Table 2
Cu-based material: CW024A EN 1653+A1
Component Material No Document
a
EN 12164
CW617N
a
EN 12165
Carbon steel EN 10253–2
1.4301, 1.4306, 1.4401, 1.4404, 1.4541, 1.4571 EN 10253–4
1.4876, 2.4360, 2.4816, 2.4819, 2.4856, 2.4858 Table 2
Thread nipple,
CW024A EN 1653+A1
Taper thread
a
nipple, EN 12164
CW602N
Threaded
a
CW608N EN 12165
connection,
CW614N a
EN 12167
copper-based material:
CW617N
Threaded fitting, a
EN 12168
c
Swivel nut
CC491K
(CuSn5Zn5Pb5-C)
EN 1982
CC499K
(CuSn5Zn5Pb2-C)
d
EN-JM1030 EN 1562
Malleable cast iron
seamless EN 10216–1 to −4
Carbon steel
welded EN 10217–3 to −5
seamless EN 10216–5
1.4301, 1.4306, 1.4401,
Pipe ends
1.4404, 1.4541, 1.4571
welded EN 10217–7
1.4876, 2.4360, 2.4816, 2.4819, 2.4856, 2.4858 See Table 2
a
copper-based material: CW024A
EN 12449
Parts attached to pressure parts
1.4301, 1.4306, 1.4401, 1.4404, 1.4541, 1.4571 EN 10028–7
Ferrule
1.4876, 2.4360, 2.4816, 2.4819, 2.4856, 2.4858 See Table 2
(similar to braid
material)
a
Cu-based material: CW450K, CW452K, CW508L
EN 12166
e
Other parts
End ring, 1.4301, 1.4306, 1.4401, 1.4404, 1.4541, 1.4571 EN 10028–7
Protective strip-
1.4876, 2.4360, 2.4816, 2.4819, 2.4856, 2.4858 See Table 2
wound hose,
Cu-based material: CW450K, CW452K, CW508L EN 1652
Anti-kink device
Braid protecting 1.4301, 1.4306, 1.4401, 1.4404, 1.4541, 1.4571,
EN 10088–3
helix 1.4310
Component Material No Document
a
Not harmonized to PED; Particular Material Appraisals (PMA) are necessary for applications within the scope
of the PED.
b
Ferritic floating flanges should be protected to avoid contamination of adjacent stainless steel parts.
c
Swivel nuts may be made from free cutting materials.
d
Malleable cast iron parts should be made weldable by multiple tempering. The carbon content of the welding
zones should not exceed 0,3 %.
e
Other parts should be preferably made from materials similar to the braid material.

5.3 Other materials
Other materials may be used provided they fulfil the general requirements of 5.1.
5.4 Corrosion
The materials selected for the metal hose assembly should have adequate resistance to all the corrosive
agents likely to be encountered during the lifetime of the system, i.e. the transported fluid and/or the
environment. Consideration should be given to all corrosion risks including pitting corrosion, inter-
granular corrosion, crevice corrosion, contact corrosion and stress corrosion cracking.
Forming and welding processes may degrade the corrosion resistance of materials.
NOTE Corrugated metal hoses generally have a wall thickness substantially less than that of the rest of the
system with which they are used. Hence they are often manufactured from a material having a higher corrosion
resistance than that used in the associated piping.
5.5 Low temperature application
Fittings such as weld ends, flanges, and threaded fittings used for low temperature applications should
not go below the temperature limits given in Table 4. The lowest allowable working temperature is
depending on the degree of load G which is defined by the maximum quotient of the stress levels
σ
resulting from the calculation of pressure resistance and the allowable stresses related to the regarded
stress components:
 
G max P /;f P /;f P+ P / 1,5⋅ f (1)
( ) ( )
σ Θ m,m m,m m,b
 
 
=
Table 4 — Materials for pressure-bearing parts at low temperature application
(Except corrugated hoses and braid)
Lowest allowable working
temperature in °C
N° Description European Standard
Degree of load G
σ
a a
1,0 0,75 0,25
Non-alloy and alloy steels with
specified properties at elevated
temperatures:
— flat products EN 10028–2
— seamless pipes EN 10216–2
– 10 – 60 – 85
b b b
— steel forgings EN 10222–2 (– 20) (– 70) (– 100)
Flat products for pressure purpose
from Nickel alloy steels with
c
2 EN 10028–4 t – 50 t – 80
min min
t
min
specified low temperature
properties
Seamless pipes for pressure
purpose, from non-alloy steels with
c
3 EN 10216–4 t – 50 t – 80
min min
t
min
specified low temperature
properties
Forgings for pressure purpose,
c
4 Nickel steels with specified low EN 10222–3 t – 50 t – 80
min min
t
min
temperature properties
Fittings for welding, with specified
c
5 EN 10253–2 t – 50 t – 80
t min min
min
low temperature properties
c
6 Fittings for welding, stainless steels EN 10253–4 t – 50 t – 80
min min
t
min
EN 10028–7
Austenitic stainless steels according
7 to Table 2 with minimum allowable EN 10216–5 – 196 – 255 – 273
temperature – 196 °C
EN 10217–7
a
Additional requirements for degree of load smaller than 1,0. No material shall be used for pressure-bearing
parts having an elongation after rupture A less than 14 % and an impact energy less than 27 J, measured on an ISO
V-notch test-piece at a temperature not greater than 20 °C and not higher than the lowest scheduled operating
temperature.
b
For materials suitable for use at −20 °C according to the relevant standard.
c
Lowest temperature of the regarded material according to the relevant standards.
Pressure-bearing parts made from materials given in Table 4 may be used at low temperatures related
to a degree of load G < 1,0 if the following additional demands are fulfilled to achieve similar safety
σ
against brittle fracture:
a) The hose manufacturer should ensure that:
1) stress raisers are avoided with regard to design and manufacture;
2) no cracks are to be expected under working conditions.
b) The hose manufacturer should in addition carry out suitable heat treatment of parts made from
ferritic materials after forming or welding.
c) Stress relieving heat treatment after welding is not necessary for ferritic materials belonging to the
material groups 1.1 or 1.2 according to CEN ISO/TR 15608 and having a wall thickness not greater
than 10 mm.
5.6 Material documentation
Materials used for metal hose assemblies should be delivered with a Declaration of compliance with the
order, type 2.1, according to EN 10204, as a minimum requirement.
Materials used for hose assemblies according to PED 2014/68/EU [1] should be delivered with
documentation as defined in EN 764-5.
6 Design methods
6.1 General
Metal hose assemblies should be adequately designed taking into account:
— all relevant factors in order to ensure that they will be safe throughout their intended life, and
— the opposing requirements of pressure resistance and flexibility.
The design should incorporate appropriate safety coefficients using comprehensive methods ensuring
adequate safety margins against all relevant loadings and failure modes in a consistent manner.
The main purpose of the design methods given below is to design a corrugated metal hose including its
braid, if used, with sufficient pressure resistance.
Two adequate design methods exist for the basic design of corrugated metal hoses:
a) a calculation design method which allows the separate design of different components of a metal
hose assembly by calculation based on allowable stresses, see 6.4. The interaction between the
different components is taken into account;
b) an experimental design method based on type approvals where specific metal hose assemblies are
subject to experimental tests. The test requirements should be based on acceptance criteria which
are indirectly based on the allowable stresses.
Both methods a) and b) may be used for the design of metal hose assemblies either separately or in
combination as appropriate for the hose designer.
This Technical Report only deals with the calculation design method.
NOTE According to the PED 2014/68/EU, Annex I, Clause 2.2.2, an experimental design method without
calculation may be used when the product of the maximum allowable pressure PS·DN is less than 3 000 bar.
6.2 Basic design criteria
6.2.1 Design conditions
Metal hose assemblies should be designed to withstand the specified pressure PS at the specified
temperature TS. This combination of pressure and temperature should as a minimum represent the
most onerous foreseeable working conditions.
The service and design conditions should be supplied to the hose manufacturer who should take them
into consideration for the design, see Annex B.
6.2.2 Temperatures
Design criteria and design methods in this standard are only valid for operating temperatures below the
creep range; i.e. up to the maximum temperatures given in Table 2 (except that for the heat resistant
austenitic steel 1.4876 and that in brackets for two nickel alloys).
6.2.3 Additional loadings
Additional loadings that may influence the design of metal hose assemblies but, are not the loads
normally regarded for the design of metal hose assemblies (see 6.2.1), should also be taken into
account.
a) Loadings present within the metal hose assembly:
1) dead weight of metal hose assembly components (i.e. corrugated hose, braiding, inner and
outer liners, protecting devices, etc.);
2) dead weight of flow medium within the metal hose assembly.
These loadings (normal or occasional) should be stated by the hose manufacturer.
b) External loadings due to adjacent piping or equipment:
1) cyclic movement (thermal expansion or forced mechanical cycles);
2) environmental (i.e. snow, wind, etc.):
3) vibration from adjacent equipment (i.e. pumps, compressors, machines, etc.);
4) shock loading (i.e. earth quake, explosion loading, etc.);
5) dynamic loading due to flow of medium or pressure pulses.
Information on external loadings (normal or occasional) should be provided.
NOTE The list of 6.2.3 is not exhaustive.
6.2.4 Structural conditions
6.2.4.1 Hose structure
Corrugated metal hoses used for metal hose assemblies with or without braiding are characterized as
follows:
a) a corrugated metal hose comprises numerous identical corrugations;
b) the corrugations are annular and axisymmetric or helical and of same cross section equidistant to
the centreline;
c) each corrugation has one, two or sometimes more plies of the same thickness (for example, see
Figure 2);
d) the braiding consists of one or more woven layers of parallel wires or braided strands;
e) for braided metal hose assemblies the active length should be such that there is at least one
complete revolution of braid along the length. Smaller active lengths are only acceptable when
reduced working characteristics are given (e.g. only vibration).
6.2.4.2 Materials
The choice of materials for metal hose assemblies should regard the requirements of Clause 5 and in
addition the following aspects:
a) if more than one ply is used, each ply is normally made of the same material;
b) when different materials are used the relevant physical properties should be taken into account;
c) where the braid material is different to that of the ply in contact with it, care should be taken that no
contact corrosion arises due to difference in galvanic potentials.
6.2.5 Dimensions
6.2.5.1 Nominal size
The nominal size DN of corrugated metal hoses and metal hose assemblies should be selected from
Table 5.
6.2.5.2 Bend radius
Minimum bend radii R of a metal hose assembly are given below:
i
R relates to hoses with high flexibility for cyclic use;
R relates to hoses with normal flexibility for cyclic use;
R relates to braided hoses for pliable applications;
R relates to unbraided hoses for pliable applications.
The minimum bend radii R related to the nominal size is given in Table 5.
i
Figure 1 — Bend radius R
Table 5 — Nominal sizes and bend radii
a
Nominal size
b
Minimum bend radius in mm (Figure 1)
DN
R
R R R 4
1 2 3
4 100 120 25 11
6 110 140 25 12
8 130 165 32 16
10 150 190 38 20
12 165 210 45 25
15 195 250 58 25
20 225 285 70 30
25 260 325 85 45
32 300 380 105 60
40 340 430 130 80
50 390 490 160 100
65 460 580 200 115
80 660 800 240 130
a
Nominal size
b
Minimum bend radius in mm (Figure 1)
DN
R
R R R 4
1 2 3
100 750 1 000 290 160
125 1 000 1 250 350 -
150 1 250 1 550 400 -
200 1 600 2 000 520 -
250 2 000 2 500 620 -
300 2 400 3 000 720 -
a
The nominal sizes are identical to those given in EN ISO 10380:2012, Table 1.
b
Values of bend radii correspond to those given in EN ISO 10380:2012, Tables 6 and 8.

6.3 Design on the basis of nominal pressures PN
Metal hose assemblies may be designed on PN basis using the pressure limits at ambient temperature,
i.e. at 20 °C.
Such hose assemblies may be designated for temperatures higher than 20 °C using derating factors for
pressure, k , which should be based on the relevant material standards, should be applied according
p, t
to the following formula:
PkPN⋅ (2)
p,t
t,max
Where Nominal pressures PN are used, they should be according to Table 6.
Table 6 — Nominal pressures PN
PN 1 2,5 4 6 10 16 25 40 63 100 160 250 320 400
NOTE The PN values are taken from EN 1333; PN 1 and PN 4 are added for better differentiation,
especially for unbraided hoses.

6.4 Allowable stresses
For main pressure-bearing parts and pressure parts other than bolts the maximum allowable stresses
(general membrane stress for predominantly static loads) should generally be determined as in Table 7.
=
Table 7 — Allowable stresses
Material a a
Design conditions Test conditions
Austenitic steel and Ni alloys
— general
  
R R
p1,0, t p1,0, tT
  
f = f =
T
  
1,5 1,05
  
  
— alternatively if A > 35 %
 
RR RR
p1,,0 t m, t p1,0, tT m, tT
 
f = min ; f = max ;
T
 
1,2 3 1,05 2
 
 
— Cold drawn braid wires with
  
R R RR
p10,, t m, t p1,0, tT m, tT
  
A ≥ 30 %
f = min ; f = max ;
w Tw
  
1,2 3 1,05 2
  
  
b c
Ferritic steel
including normalized (normalized
 
RR R
p0,2, t m, 20 p0,2, tT
 
rolled) steel
f = min ; f =
T
 
1,5 24, 1,05
 
 
a
Proof stress Rp1,0 may be replaced by yield strength Rp0,2 if Rp1,0 is not available
b
Proof stress R may be replaced by yield strength R for ferritic steels.
p0,2 eH
c
Fine-grained steel and specially heat-treated steel, non-alloy or low-alloy cast steel are excluded.

Where materials are used having higher proof stresses and sufficient strains to rupture certified by the
material manufacturer in an inspection certificate according to EN 10204, type 3.1 or 3.2, the allowable
stresses may be increased. The increase should not be more than 50 % of the difference between the
specified values of the standards and the certified values in the certificate divided by the relevant safety
factor.
7 Calculation design method
7.1 General
A detailed method is provided to calculate the design of hose assemblies subject to internal pressure
and temperature. The method is applicable to unbraided and braided hose assemblies, as relevant.
The different parts of the metal hose assembly are calculated separately:
a) calculation of corrugated metal hose given in 7.2;
b) calculation of braiding given in 7.3;
c) calculation of metal hose assembly given in 7.4.
7.2 Corrugated metal hose
7.2.1 Scope
This subclause applies to two types of corrugated hoses having nominally U-shaped corrugations
according to the limitations given in this subclause.
a) A design according to Figure 2a) is generally manufactured from a pre-fabricated butt welded tube
by a forming process (e.g. hydraulic or roll forming) without any circumferential welds in the
corrugations. The corrugations are annular or helical and consist of one or more plies.
b) A design according to Figure 2b) is manufactured from a pre-fabricated corrugated profile strip
wound over an inner tool and resistance welded at the crest. The corrugations are helical and
consist of one or two plies in the sidewalls.

a) Cross section of the butt welded design
b) Cross section of the resistance welded design
Figure 2 — Cross section of the corrugation
7.2.2 General factors
The general factors given below should apply for the design of corrugated metal hoses.
Where different formulae are used for general factors of the two different designs, they are given in
Table 8. The further general factors do not differ with respect to the design.
Table 8 — General factors for the two different hose designs
Design
Figure 2 a) Figure 2 b)
Number of plies n : Total number of plies n : Number of plies in the sidewall
p p
∗
A =
A 22⋅ n ⋅ e ⋅ w+ r ⋅ π− c
{ ( )}
cmpp

 
Cross sectional  

∗
 
(3a)  
2 ⋅ n ⋅ e ⋅ w + r ⋅ π ⋅ 1 + − 2
metal area of 
pp m
   
2 ⋅ n

p
one corrugation  
 

(3b)
1 1
∗ ∗

r = ⋅ b + b − 2⋅ ne⋅ r = ⋅ bb+ −⋅2 n + 1⋅ e
( )
( )
m r c pp m r c pp


4 4
Mean radius of
1 1
∗ ∗
=⋅−be =⋅ bn−+ 0,5⋅ e
crest and root ( )
( ) ( )
m m p p
2 2
(4a) (4b)
Hose corrugation’s effective area:
π
AD⋅ (5)
e m
Calculating factors used to determine calculation coefficient C , C , C (see Annex A):
p f d
2 ⋅ r
m
, (6)
C =
w
2 ⋅ r
m
C = . (7)
∗
1,1⋅⋅D e
mp
Mean diameter:
(8)
D DD+ / 2
( )
m io
Outer diameter:
D D+⋅2 w+ e (9a)
( )
oi
DD=++2./w 54e (9b)
( )
o i
=
=
=
=
Equivalent ply thickness:
05,

e ⋅ D D for forming from inside to outside; e.g. hydraulic forming
 ( )
p i m
0,25

∗
e e⋅ D D for forming partly to inside and outside; e.g. free roll forming (10a)

( )
p p i m

e for forming from outside to inside ; e.g. controlled roll forming
p


NOTE For the third case of the Formula (10a), it is assumed that the thickness remains substantially constant
over the entire cross section.
∗
Where the equivalent thickness e is defined by measured dimensions on a manufactured corrugation
p
profile representative of production it is given by:

ee+ + e 3 for forming 100% to inside or outside; e.g. hydraulic forming
 ( )
∗
p, c p, m p, r
e = (10b)

p
e +⋅2 e + e 4 for forming partly to outside and inside; e.g. free roll forming
( )
 p, c p, m p, r

Apply “forming from inside to outside” for hose design according to Figure 2 b).
The ply thickness e used for the manufacture of the corrugated hose is equal to the nominal thickness
p
of the strip material in accordance with EN ISO 9445-1:2010, Table 1 and EN ISO 9445-2:2010,
t
n
Table 1.
The tolerances of the nominal thickness t of the strip material should be in accordance with
n
EN ISO 9445-1:2010, Table 1 and EN ISO 9445-2:2010, Table 1, but the minimum thickness should be
not less than 90 % of the nominal thickness.
Equivalent total wall thickness:
∗∗
e ne⋅ , (11)
pp
Axial force due to pressure (pressure thrust):
F PA⋅ (12)
Pe
Corrugation height:
DD−
( )
oi
∗
w −⋅ne (13)
pp
Calculation coefficients C , C and C are given in Annex A.
p f d
7.2.3 Limiting conditions
This calculation method is valid for corrugated metal hoses which meet the following conditions. When
these conditions are not met, only experimental design should be accepted.
a) The mean radius of the torus r at the crest and the root of the corrugations should be nominally
m
the same.
A variation of ± 20 % between the real mean radiuses at the crest or the root in relation to the
mean value of both is permitted.
=
=
=
=
b) The mean torus radius should be such that:
r ≥ 3 · e
m
p
c) The corrugation height should be such that:
D
i
≥ w ≥ 2 ⋅ r
m
Figure 3 — Possible corru
...