BS EN 13480-4: 2002 Metallic industrial piping - Part 4: Fabrication and installation (Eng)
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EN 13480-4:2002 (E)
Issue 1 (2002-05)
9
5.6 Tolerances
Tolerances shall comply with EN ISO 13920:1996, class C and class G except where other classes are specified in
this European Standard.
Angular tolerances for fabricated pipework shall be determined by the dimensional tolerance for the terminal points
of the finished part.
Alternative tolerances for fabrication and installation of pipework shall be determined and in all cases these shall be
identified in the specification. Dimensional tolerances for fabricated spools shall comply with Annex B.
6 Cutting and bevelling
6.1 General
Cutting and bevelling by machining shall be permitted for all materials.
Flame cutting shall be permitted for material groups 1, 2, 3, 4 and 5 only with preheating as for welding.
NOTE Flame cutting for material groups 1 and 2 can be used for bevelling, if the required bevel forms and tolerances can
be achieved and the heat affected zone has no detrimental effects on the quality of the weld.
For material groups 3, 4 and 5, the heat affected zone shall be removed by machining or grinding.
Plasma cutting shall be permitted for all material groups given in this European Standard. Plasma cutting shall be
preceded by preheating, as specified for welding in 9.11.1.
Other cutting and bevelling processes shall be permitted, provided their suitability is demonstrated.
6.2 Transfer of marking for pressure parts
For pressure parts, identification of materials shall remain possible, either by retaining or by transferring the mark
stipulated by the product standard, or by using a unique code kept in the records of the piping fabricator.
Stamping shall not introduce a notching effect, therefore stamping with round edges is recommended.
If any method of marking other than hard-stamping or engraving (vibrograph) is used, the fabricator shall ensure
that confusion between different materials is not possible, e.g. by separate handling (time and/or place), stamped
bands.
7 Bending and other forming
7.1 General
7.1.1
Fabricators of formed pressure parts shall have adequate equipment for the forming procedures and the
subsequent heat treatment.
NOTE 1 Forming of expansion bellows is specified in EN 13445-3:2002, clause 14.
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EN 13480-4:2002 (E)
Issue 1 (2002-05)
10
Pipes with internal coating such as glass, rubber or plastics shall not be formed unless it has been demonstrated
that the forming process is not detrimental to the lining.
NOTE 2 There are two kinds of forming within the scope of this standard: cold forming and hot forming.
The thickness after bending or forming shall be not less than that required by the design.
NOTE 3 Longitudinal welds should be located at the neutral zone. The range of the neutral zone after bending is given in
Figure 7.1.1-1.
Key
1 extrados
2 intrados
a optimal range for the longitudinal weld seam at bending
b weld seam
Figure 7.1.1-1 — Optimal range for the longitudinal weld seam at bending
7.1.2
The forming and post-forming heat treatment of thermomechanical steels shall be given individual
consideration. Account shall be taken of the recommendations of the steelmakers.
NOTE Pipes whose properties have been generated by thermomechanical means such as controlled rolling can be formed by
hot or cold methods. Such materials may be substantially changed by the forming process and require particular consideration
to ensure that the specified properties are recovered after forming.
7.1.3
The following equations shall be used for the calculation of the percentage deformation for cold formed
cylinders and cone products made by rolling (see Figure 7.1.3-1) :
a) For cylinders and cones rolled from flat materials (see Figures 7.1.3-1a) and 7.1.3-1c)):
mf
ord
d
50
r
e
V
(7.1.3-1)
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EN 13480-4:2002 (E)
Issue 1 (2002-05)
11
b) For cylinders and cones rolled from intermediate product (see Figures 7.1.3-1b) and 7.1.3-1c)) :
mi
mf
mf
int
d
1
50
r
r
r
e
V
(7.1.3-2)
where
ord
e is the ordered thickness;
int
e is the thickness of the intermediate product;
mf
r
is the average radius of the finished product;
mi
r
is the average radius of the intermediate product;
V
d
is the deformation as a percentage.
NOTE If no intermediate quality heat treatment is applied between individual forming steps, the deformation is the total
amount of deformation of the individual steps. If intermediate quality heat treatment is applied between the forming steps, the
deformation is that deformation applied after the last treatment.
a) Initial product b) Intermediate product c) Finished product
Figure 7.1.3-1 — Forming of cylinders and cones
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EN 13480-4:2002 (E)
Issue 1 (2002-05)
12
7.1.4
Tools and equipment used for forming shall be maintained to ensure a smooth profile free from scores,
scratches or other stress-raising defects.
7.1.5
Heat treatment after forming shall be in accordance with the respective material standard.
7.1.6
Welding on to formed areas shall not be performed until heat treatment is complete.
7.2 Heat treatment after cold forming
7.2.1 Flat products
Flat products shall be heat treated after cold forming as required in Table 7.2.1-1.
NOTE 1 For special design reasons, for example cyclic loading or stress corrosion, heat treatment in excess of that in Table
7.2.1-1 may be specified after cold forming.
For austenitic steels having a required minimum value of elongation at rupture
A
5
equal to or greater than 30 %, a
maximum level of 15 % cold deformation shall be acceptable.
NOTE 2 A greater deformation may be accepted if the evidence is supplied that there is a minimum elongation at break of
15 % after cold forming.
Such evidence shall be deemed supplied, if the acceptance certificate shows that elongation at rupture
A
5
is not
less than 30 %. This shall be applicable only in cases where there is no risk of stress corrosion cracking.
For austenitic steels having a required minimum value of elongation at rupture
A
5
less than 30 %, evidence shall be
supplied that there is a minimum residual elongation of 15 % after cold forming.
Deformation shall not exceed 10 % if the working temperature is below - 196 °C.
Table 7.2.1-1 — Heat treatment after cold forming of flat products
Material groups according to
CR ISO 15608:2000
Deformation Heat treatment
1.1, 1.2, 1.3, 2.1, 2.2
a
, , 3, 4
b
, 5.1,
5.2
b
, 5.3
b
, 5.4
b
, 6
b
,
5 %
no
7.1, 7.2, 7.3, 10, 11 > 5 % yes
8.1, 8.2
cc
9.1, 9.2
dd
a
If not heat treated, qualification tests are required to demonstrate that the material properties are not
impaired.
b
Special heat treatment required in accordance with the material standards where the minimum design
temperature is below - 10 °C.
c
Solution annealed and quenched or stabilized materials do not require heat treatment after cold forming.
d
To be considered in the first amendment.
7.2.2 Pipes
Pipes shall be heat treated after cold forming in accordance with Table 7.2.2-1.
NOTE For special reasons, for example cyclic loading or stress corrosion, heat treatment may be specified after
cold forming.
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EN 13480-4:2002 (E)
Issue 1 (2002-05)
13
Table 7.2.2-1 — Heat treatment after cold forming of pipes
Material groups
according to
CR ISO 15608:2000
Mean bending radius
of the pipe
r
m
Outside
diameter of the
pipe
d
o
Heat treatment
r
m
1,3
d
o
all diameters yes
d
o
142 mm
no
1,3
d
o
<
r
m
< 2,5
d
o
d
o
> 142 mm
yes
c
1,1 1.2, 1.3
2.1,
2.2
b
,
3
b
4
a
5.1, 5.2
a
, 5.3
a
, 5.4
a
6
a
7
8
9
10, 11
2,5
d
o
r
m
all diameters no
NOTE For
d
o
and
r
m
, see Figure 7.2.2-1.
a
Special heat treatment required in accordance with the material standards where the minimum design
temperature is below - 10 °C.
b
If not heat treated, qualification tests are required to demonstrate that the material properties are not
impaired.
c
Not required for material groups 8.1, 8.2.
Figure 7.2.2-1 — Pipe bending
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EN 13480-4:2002 (E)
Issue 1 (2002-05)
14
7.3 Heat treatment after hot forming
7.3.1 Material groups 1, 2, 3, 4, 5, 6 and 7
After hot forming, including induction bending, the parts shall be heat treated in accordance with the material
specification to ensure that the properties meet those required by the material standard, or other appropriate
specification. Special consideration shall be given to materials designed to operate at elevated or sub-zero
temperatures or other special conditions.
NOTE 1 If the hot forming of materials of groups 1, 2, 3, 5 up to 2 % Cr and group 7 has been started and ended within the
temperature range fixed in the material specification :
forming temperature.
NOTE 2 Pipes bent using the incremental induction heating method (induction bends) may undergo thermal treatment during
bending by the application of water or air quenches.
NOTE 3 Carbon and carbon manganese steels formed using the induction bending process with air or water quenching may
be suitable in the as-bent condition for applications where high impact resistance and ductility are not required. Such bends may
be supplied without post-bending heat treatment provided that bend hardness does not exceed 285 HV.
NOTE 4 Heat treatments for high alloyed ferritic material should follow as soon after forming as practicable, to minimise the
risk of hydrogen induced cracking.
The manufacturer shall demonstrate that the requisite properties are achieved in the final product by the
examination and testing of one or more sample bends. These bends shall be made in accordance with all the
relevant parameters to be used in production bends. These parameters include, but are not limited to, chemical
composition, forming temperature, forming rate (speed), forming coolant supply, forming dimensions (e.g. bend
radius and
r
m
/
d
o
) and post-forming heat treatment.
7.3.2 Material groups 8.1, 8.2 and 8.3
Austenitic steels which have been rapidly cooled from above the solution annealing temperature using water or air
during the forming process shall not require post-forming heat treatment. Stabilized austenitic steels formed above
the solution annealing temperature shall be subjected to post-forming stabilizing treatment. Stabilized austenitic
steels formed in the stabilizing temperature range, shall not require subsequent treatment.
Heat treatment shall be carried out in accordance with Table 7.3.2-1.
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EN 13480-4:2002 (E)
Issue 1 (2002-05)
15
Table 7.3.2-1 — Heat treatment of austenitic steels after hot forming
Typical steel grades in accordance with
EN 10088-1
Conditions under which post-forming
heat treatment may be waived
Temperature range for heat treatment
when stabilizing
a
Solution annealing
temperature
b,c
°C
Material type
Name Number Non-welded parts Welded parts Non-welded parts
°C
Welded parts
°C
Stabilized steels
non-Mo-alloyed
X 6 CrNiTi 18-10
X 6 CrNiNb 18-10
1.4541
1.4550
900 ± 20
(L)
c
920 ± 20
1 020
X 6 CrNiMoTi 17-12-2
X 6 CrNiMoNb 17-12-2
1.4571
1.4580
not permitted
d
not permitted
d
Mo-alloyed
(X 4 NiCrMoCuNb 20-18
e,f
)
1.4505
1 050
non stabilized steels
low C-content /non-
Mo-alloyed
X 2 CrNi 19-11
X 2 CrNiN 18-10
1.4306
1.4311
900 ± 20
(L)
c
920 ± 20
(L)
c, h
1 000
X 2 CrNiMo 17-12-2
X 2 CrNiMo 18-14-3
X 2 CrNiMoN 17-11-2
1.4404
1.4435
1.4406
960 ± 20 °C
(L)
c, e
980 ± 20
(L)
c, h, i
1 020
low C-content /Mo-
alloyed
X 2 CrNiMoN 17-13-3
X 2 CrNiMo 18-15-4
X 2 CrNiMoN 17-13-5
1.4429
1.4438
1.4439
Forming started at
1 000 °C
g
to 1 150 °C and
finished at > 750 C (fastest
possible Cooling).
Forming started at 1 000 °C to
1 150 °C and finished at > 750 °C
(fastest possible Cooling) and
stabilized fillers or non-stabilized
fillers with 0,04 % C in weld
metal
1 040
high C-content /non
Mo-alloyed
X 4 CrNi 18-10
X 4 CrNi 18-12
1.4301
1.4303
not permitted not permitted
1 000
high C-content/Mo-
alloyed
X 5 CrNiMo 17-12-2
X 3 CrNiMo 17-13-3
1.4401
1.4436
Forming started at
1 000 °C
g
to 1 150 C
e
and
finished at > 875 °C
(quenching in/with water for
wall thicknesses 6 mm)
Forming started at 1 000°C to
1 150 °C
e
and finished at
> 875°C (quenching in/with water
for wall thicknesses 6 mm) and
stabilized fillers or non-stabilized
fillers with 0,06 % C
1 050
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EN 13480-4:2002(E)
Issue 1 (2002-05)
16
a
Stabilizing or corresponding annealing in the case of non stabilized steels with approximately 30 min critical interval.
b
For e
ord
6 mm the type of cooling shall be quenching in/with water or cooling in air flow (W SL).
c
For e
ord
< 6 mm cooling shall be in air flow (L).
d
Unless required by process conditions.
e
Minimal critical interval is 5 min.
f
Materials not in EN 10088-1.
g
Starting temperature of 1 000 °C may be lowered if part was in the quenched state prior to hot forming.
h
Stabilizing not permissible if stabilized fillers are used.
i
Steels No. 1.4406 and 1.4429 may be stabilized at lower temperatures if the same material characteristics will be reached.
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EN 13480-4:2002(E)
Issue 1 (2002-05)
17
7.3.3 Heat treatment after hot forming for material group 10
After hot forming, the parts shall be heat treated in accordance with the material specifications.
7.3.4 Heat treatment after hot forming for material group 11 and clad materials
If forming cannot be avoided, then the process of forming and heat treatment shall be demonstrated as giving
specified properties
.
7.4 Tolerances
7.4.1 Out-of-roundness of bends under internal pressure equal to, or greater than, the external pressure
The out-of-roundness,
u
(in %), shall be calculated from:
100
2
minomaxo
minomaxo
dd
dd
u
(7.4.1-1)
where
maxo
d
is the maximum outside diameter measured, in mm;
mino
d
is the minimum outside diameter measured at the same cross section as
maxo
d
, in mm.
The out-of-roundness of the bend shall not exceed the limits given in Figure 7.4.1-1.
The ends of the bent pipes shall comply with the tolerances for the base pipe.
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EN 13480-4:2002(E)
Issue 1 (2002-05)
18
Key
d
o
is the outside diameter ;
r
m
is the mean bending radius ;
u
is the out-of-roundness
Figure 7.4.1-1 — Acceptable out-of-roundness
7.4.2 Out-of-roundness of bends under external pressure and vacuum
Values for out-of-roundness shall be conform to the values stated in the design.
7.4.3 Waves at bends
There shall be no waves at bends, unless the waves comply with both of the following conditions:
a)
m
h 0,03
d
01
(7.4.3-1)
where
h
m
is the mean height of adjacent waves, calculated as follows:
03
0402
m
2
d
dd
h
(7.4.3-2)
where
d
01,
d
02,
d
03
,
d
04
are as shown in Figure 7.4.3-1
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