EN ISO 11120:2015

SLOVENSKI STANDARD
01-maj-2015
1DGRPHãþD
SIST EN ISO 11120:2000
SIST EN ISO 11120:2000/A1:2013
Plinske jeklenke - Ponovno polnljive velike jeklenke iz celega iz jekla z vodno
prostornino od 150 do 3000 l - Konstruiranje, izdelava in preskušanje (ISO
11120:2015)
Gas cylinders - Refillable seamless steel tubes of water capacity between 150 l and 3000
l - Design, construction and testing (ISO 11120:2015)
Gasflaschen - Wiederbefüllbare nahtlose Großflaschen aus Stahl mit einem
Fassungsraum zwischen 150 l und 3 000 l - Ausführung, Bau und Prüfung (ISO
11120:2015)
Bouteilles à gaz - Tubes en acier sans soudure rechargeables d'une contenance en eau
de 150 l à 3000 l - Conception, construction et essais (ISO 11120:2015)
Ta slovenski standard je istoveten z: EN ISO 11120:2015
ICS:
23.020.30 7ODþQHSRVRGHSOLQVNH Pressure vessels, gas
MHNOHQNH cylinders
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 11120
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2015
ICS 23.020.30 Supersedes EN ISO 11120:1999
English Version
Gas cylinders - Refillable seamless steel tubes of water capacity
between 150 l and 3000 l - Design, construction and testing (ISO
11120:2015)
Bouteilles à gaz - Tubes en acier sans soudure Gasflaschen - Wiederbefüllbare nahtlose Großflaschen aus
rechargeables d'une contenance en eau de 150 l à 3000 l - Stahl mit einem Fassungsraum zwischen 150 l und 3 000 l -
Conception, construction et essais (ISO 11120:2015) Auslegung, Bau und Prüfung (ISO 11120:2015)
This European Standard was approved by CEN on 4 October 2014.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

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, 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
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11120:2015 E
worldwide for CEN national Members.

Contents Page
Foreword .3
Foreword
This document (EN ISO 11120:2015) has been prepared by Technical Committee ISO/TC 58 "Gas cylinders"
in collaboration with Technical Committee CEN/TC 23 “Transportable gas cylinders” the secretariat of which is
held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by August 2015, and conflicting national standards shall be withdrawn at
the latest by August 2015.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 11120:1999.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 11120:2015 has been approved by CEN as EN ISO 11120:2015 without any modification.
INTERNATIONAL ISO
STANDARD 11120
Second edition
2015-02-01
Gas cylinders — Refillable seamless
steel tubes of water capacity
between 150 l and 3000 l — Design,
construction and testing
Bouteilles à gaz — Tubes en acier sans soudure rechargeables d’une
contenance en eau de 150 l à 3000 l — Conception, construction et essais
Reference number
ISO 11120:2015(E)
©
ISO 2015
ISO 11120:2015(E)
© ISO 2015
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2015 – All rights reserved

ISO 11120:2015(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Inspection and testing . 3
6 Materials . 3
6.1 General requirements . 3
6.2 Controls on chemical composition . 4
6.3 Heat treatment . 5
6.4 Mechanical properties . 5
6.5 Failure to meet test requirements . 5
7 Design . 6
7.1 Calculation of cylindrical shell thickness . 6
7.2 Design of tube ends . 6
7.3 Design drawing . 7
8 Construction and workmanship . 7
8.1 General . 7
8.2 Surface imperfections . 7
8.3 Ultrasonic examination . 7
8.4 End closure (fitting) . 7
8.5 Dimensional tolerances . 7
8.5.1 Out-of-roundness . 7
8.5.2 Outside diameter . 7
8.5.3 Straightness . 8
8.5.4 Eccentricity . 8
8.5.5 Length. 8
8.5.6 Water capacity . 8
8.5.7 Mass . 8
9 Type approval procedure . 9
9.1 General requirements . 9
9.2 Prototype tests . 9
9.3 Type approval test report .10
9.4 Type approval certificate.10
10 Batch tests .10
10.1 General requirements .10
10.2 Mechanical tests .10
10.2.1 General requirements .10
10.2.2 Tensile test .11
10.2.3 Impact testing .11
10.3 Interpretation of results .11
11 Tests on every tube.11
11.1 General .11
11.2 Hydraulic test .12
11.2.1 Proof pressure test .12
11.2.2 Volumetric expansion test .12
11.3 Hardness testing .12
11.4 Visual inspection .13
ISO 11120:2015(E)
11.5 Dimensional inspection .13
11.5.1 Thickness .13
11.5.2 Diameter and length .13
11.5.3 Water capacity and mass .13
11.5.4 Neck threads and openings .13
11.6 Ultrasonic non-destructive test .13
12 Special requirements for tubes for embrittling gases .14
12.1 General .14
12.2 Materials .14
12.3 Design .14
12.4 Construction and workmanship .14
12.4.1 General.14
12.4.2 Surface imperfections .14
12.5 Mechanical tests .15
12.5.1 Tensile and impact tests .15
12.5.2 Hardness test .15
13 Inspection certificate .15
14 Marking .16
Annex A (informative) Typical chemistry groupings for seamless steel tubes .17
Annex B (normative) Ultrasonic examination .18
Annex C (informative) Description and evaluation of manufacturing imperfections
and conditions for rejection of seamless steel tubes at time of final inspection
by the manufacturer .23
Annex D (informative) Acceptance certificate .29
Annex E (informative) Type approval certificate .31
Annex F (informative) Bend stress calculation .32
Bibliography .33
iv © ISO 2015 – All rights reserved

ISO 11120:2015(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 58, Gas cylinders, Subcommittee SC 3, Cylinder design.
This second edition cancels and replaces the first edition (ISO 11120:1999), which has been technically
revised by the following:
— Annex A “Typical chemistry groupings for seamless steel tubes” is informative;
— nickel chromium molydbenum steel has been added in 6.1.1 and Annex A as Group V;
— reduction of maximum sulfur content in 6.2.2 from 0,020 % to 0,010 %; also the sum of sulfur and
phosphorus is reduced from 0,030 % to 0,025 %;
— the modification of ultrasonic provisions for ultrasonic examination in 8.3 to include ultrasonic
examination for wall thickness and for imperfections also on the supplied tubing;
— “Type Approval Procedure” has been introduced in Clause 9;
— the provisions for design of tubes for embrittling gases have been revised.
It also incorporates ISO 11120:1999/Amd 1:2013.
ISO 11120:2015(E)
Introduction
This International Standard provides a specification for the design, manufacture, inspection and testing
of tubes at the time of manufacture for worldwide usage. The objective is to balance design and economic
efficiency against international acceptance and universal utility.
This International Standard aims to eliminate concern about climate, duplicate inspections and
restrictions currently existing because of lack of definitive International Standards. It does not reflect
on the suitability of the practice of any nation or region.
This International Standard addresses the general requirements on design, construction and initial
inspection and testing of pressure receptacles of the United Nations Recommendations on the Transport
of Dangerous Goods: Model Regulations.
It is intended to be used under a variety of regulatory regimes, but it is suitable for use with the
conformity assessment system for UN pressure receptacles of the above-mentioned Model Regulations.
vi © ISO 2015 – All rights reserved

INTERNATIONAL STANDARD ISO 11120:2015(E)
Gas cylinders — Refillable seamless steel tubes of
water capacity between 150 l and 3000 l — Design,
construction and testing
1 Scope
This International Standard specifies minimum requirements for the material, design, construction and
workmanship, manufacturing processes, examinations and tests at manufacture of refillable quenched
and tempered seamless steel tubes of water capacities exceeding 150 l up to and including 3 000 l
for compressed and liquefied gases exposed to extreme world-wide ambient temperatures, normally
between –50 °C and +65 °C.
This International Standard is applicable to tubes with a maximum tensile strength, R , of less than
ma
1 100 MPa. These tubes can be used alone or in batteries to equip trailers or multiple element gas
containers (ISO modules or skids) for the transportation and distribution of compressed gases.
This International Standard is applicable to tubes having an opening at each end.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method
ISO 148-2, Metallic materials — Charpy pendulum impact test — Part 2: Verification of testing machines
ISO 148-3, Metallic materials — Charpy pendulum impact test — Part 3: Preparation and characterization
of Charpy V-notch test pieces for indirect verification of pendulum impact machines
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method
ISO 6506-2, Metallic materials — Brinell hardness test — Part 2: Verification and calibration of testing machines
ISO 6506-3, Metallic materials — Brinell hardness test — Part 3: Calibration of reference blocks
ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
ISO 11114-1, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 1:
Metallic materials
ISO 11114-4, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas
contents — Part 4: Test methods for selecting metallic materials resistant to hydrogen embrittlement
ISO 13769, Gas cylinders — Stamp marking
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO 11120:2015(E)
3.1
yield strength
stress value corresponding to the upper yield strength, R , or, for steels that do not exhibit a defined
eH
yield, the 0,2 % proof strength (non-proportional extension), R
p0,2
Note 1 to entry: See ISO 6892-1.
3.2
quenching
hardening heat treatment in which a tube, which has been heated to a uniform temperature above the
upper critical point, Ac , of the steel, is cooled rapidly in a suitable medium
3.3
tempering
toughening heat treatment which follows quenching, in which the tube is heated to a uniform temperature
below the lower critical point, Ac , of the steel
3.4
tube
seamless transportable pressure receptacle of a water capacity exceeding 150 l but not more than 3 000 l
3.5
batch
quantity of up to 30 tubes of the same nominal diameter, thickness and design made successively from the
same steel cast and processed in the same heat treatment equipment (i.e. a continuous furnace process or a
single furnace charge, for both austenitization and tempering) using the same heat treatment parameters
3.6
test pressure
p
h
required pressure applied during a pressure test
Note 1 to entry: It is used for tube wall thickness calculation.
3.7
design stress factor
F
ratio of the equivalent wall stress at test pressure, p , to guaranteed minimum yield strength, R
h eg
3.8
laminar imperfection
any imperfection lying essentially parallel to the tube surface, within the thickness of the product
3.9
working pressure
settled pressure of a compressed gas at a uniform reference temperature of 15 °C in a full tube
4 Symbols
a Calculated minimum thickness, in millimetres, of the cylindrical shell
a′ Guaranteed minimum thickness, in millimetres, of the cylindrical shell
A Percentage elongation after fracture
D Nominal outside diameter of the tube, in millimetres
f A constant in the design stress factor (see 12.3)
F Design stress factor (variable) (see 3.7)
2 © ISO 2015 – All rights reserved

ISO 11120:2015(E)
L Original gauge length, in millimetres, according to ISO 6892-1
1)
p Hydraulic test pressure, in bar , above atmospheric pressure
h
p Working pressure, in bars, above atmospheric pressure
w
R Minimum guaranteed value of yield strength, in megapascals
eg
R Actual value of the yield strength, in megapascals, as determined by the tensile test
ea
(see 10.2.2)
R Minimum guaranteed value of the tensile strength, in megapascals
mg
R Actual value of tensile strength, in megapascals, as determined by the tensile test
ma
(see 10.2.2)
R Maximum guaranteed value of the tensile strength, in megapascals
m max
S Original cross-sectional area of tensile test piece, in square millimetres, according to
ISO 6892-1
1) 5 5 2
1 bar = 10 Pa = 10 N/m
5 Inspection and testing
Evaluation of conformity shall be carried out in accordance with the applicable regulations of the
countries of use.
To ensure that the tubes conform to this International Standard, they shall be subject to inspection
and testing in accordance with Clauses 9, 10 and 11 by an inspection body, hereafter referred to as the
“Inspection Body”, authorized to do so.
Equipment used for measurement, testing and examination during production shall be maintained and
calibrated within a documented quality management system.
6 Materials
6.1 General requirements
6.1.1 Materials for the manufacture of tubes shall meet the requirements of 6.2, 6.3 and 6.4.
Steel for the fabrication of tubes shall be of nationally or internationally recognized compositions having
proven reliability. Tubes shall be manufactured from carbon steel, carbon manganese steel, chromium-
molybdenum steel, nickel-chromium-molybdenum steel, chromium-molybdenum-vanadium steel, or a
similar alloy steel.
NOTE Steels of the types shown in Annex A have been proven to be acceptable by experience.
The steel shall be at least 95 % iron. New steel compositions, and steels for which limited experience
exists in tube/cylinder service, shall be fully tested and approved by an authorized body and have been
manufactured from not less than five casts of steel. The manufacturer of the finished tube shall provide
a detailed specification with tolerances for the supplied tubing including
— chemical composition,
— dimensions, and
— surface quality.
ISO 11120:2015(E)
6.1.2 The material used for the manufacture of tubes shall be steel, other than rimming quality, fully
killed with aluminium and/or silicon.
The material shall have non-ageing properties, having a sufficient amount of nitrogen binding elements
(e.g. Al ≥ 0,015 %).
In cases where examination of this non-ageing property is required by the customer, the criteria by
which it is to be specified shall be agreed with the customer and shall be part of the order.
6.1.3 In order to prove the heat treatability of a certain tube type, it is recommended that the manufacturer
of the tubing supply a certificate of mechanical properties, as a guidance to the tube manufacturer to
achieve the properties required by this International Standard. This certificate is obtained carrying out a
reference heat treatment, representative of the final heat treatment, on a sample of tubing.
6.1.4 The tube manufacturer shall establish means to identify the tubes with the cast of steel from
which they are made.
6.1.5 Grades of steel used for tube manufacture shall be compatible with the intended gas service,
e.g. corrosive gases and embrittling gases (see ISO 11114-1).
NOTE Additional requirements related to tubes for use with embrittling gases are given in Clause 12.
6.2 Controls on chemical composition
6.2.1 A steel is defined by the steel-making process and by its chemical composition.
Steel-making shall be defined by reference to a given process (oxygen converter, electric arc furnace or
equivalent) and to the killing method.
The chemical composition of the steel shall be defined at least by:
— the carbon, manganese and silicon contents in all cases,
— the chromium, nickel, molybdenum, vanadium or niobium contents when these are alloying elements
intentionally added to the steel, and
— the maximum sulfur and phosphorus contents in all cases.
The carbon, manganese and silicon contents and, where appropriate, the chromium, nickel, molybdenum,
vanadium or niobium contents shall be given, with tolerances, such that the differences between the
maximum and minimum values of the cast do not exceed the ranges shown in Table 1.
Table 1 — Chemical composition tolerances
Maximum content Permissible range
(mass fraction) (mass fraction)
Element
% %
Carbon <0,30 0,06
≥0,30 0,07
Manganese All values 0,30
Silicon All values 0,30
Chromium <1,50 0,30
≥1,50 0,50
Nickel All values 0,40
Molybdenum All values 0,15
4 © ISO 2015 – All rights reserved

ISO 11120:2015(E)
Elements not included in the declared chemical composition shall not be deliberately added. The content
of such elements shall be limited to ensure that they have no detrimental effect on the properties of the
finished product.
The combined content of the elements vanadium, niobium, titanium, boron and zirconium, shall not
exceed 0,15 %. This requirement shall not apply to Group IV steels as per Annex A.
The actual content of any element deliberately added shall be reported and their maximum content shall
be representative of good steel making practice.
6.2.2 The maximum sulfur and phosphorus contents in the cast and check analyses shall not exceed
0,010 % and 0,020 %, respectively, and their sum shall not exceed 0,025 %.
6.2.3 The manufacturer of the finished tube shall obtain and make available the certificate of cast (heat)
analyses of the steel supplied for the construction of the tube.
6.3 Heat treatment
6.3.1 Each tube shall be heat treated, and for each stage of treatment, i.e. quenching and tempering, the
heat treatment procedure shall include a record of
— the temperature,
— the temperature holding time, and
— the cooling medium.
6.3.2 Heat treatment shall be carried out in such a way that it does not induce excessive stresses which
could initiate irreversible damage in the tube.
6.3.3 The austenitization temperature prior to quenching shall be within ±30 °C of the temperature
retained for the steel type concerned, but it shall never be less than the upper critical point (Ac ) of the
steel concerned.
6.3.4 Quenching in media other than oil or air is permissible provided that the method produces tubes
free of cracks as verified by non-destructive examination.
6.3.5 The tempering temperature shall be within ±30 °C of the temperature for guaranteeing specified
mechanical properties but shall not be less than 540 °C.
6.4 Mechanical properties
The mechanical properties of the finished tube or the test ring shall be verified according to 10.2 and
11.3 and the results shall be in compliance with the design drawing.
6.5 Failure to meet test requirements
6.5.1 In this clause, test requirements cover only the tests required in Clauses 9, 10 and 11.
6.5.2 In the event of failure to meet test requirements, retesting or reheat treatment and retesting shall
be carried out as follows.
a) If there is evidence of a fault in carrying out a test, or an error of measurement, a further test shall
be performed. If the result of this test is satisfactory, the first test shall be ignored.
ISO 11120:2015(E)
b) If the test has been carried out in a satisfactory manner, the cause of test failure shall be identified.
1) If the tubes do not meet the required mechanical properties due to the heat treatment applied,
the manufacturer may subject all the tubes of the batch to one further heat treatment or reject
the corresponding tubes. If one or more tests prove even partially unsatisfactory results, all the
tubes of the batch shall be rejected.
2) If the failure is due to a cause other than the heat treatment applied, all tubes with imperfections
shall be either rejected or repaired such that the repaired tubes pass the test(s) required for the
repair. They shall then be re-instated as part of the original batch.
6.5.3 Where reheat-treatment is required, the tubes shall be re-tempered or re-quenched and
tempered. A maximum of two austenitizing treatments is permitted. Whenever tubes are reheat-treated,
the wall thickness can be affected by scale formation, therefore the guaranteed minimum thickness shall
be checked in the finished tube.
7 Design
7.1 Calculation of cylindrical shell thickness
The guaranteed minimum thickness of the cylindrical shell, a′, shall be not less than the thickness
calculated using the Lamé-von Mises formula, as follows:
 
10FR − 3p
D
eg h
 
a=−1 (1)
 
2 10FR
eg
 
where the value of F is the lesser of 0,65/(R /R ) or 0,85.
eg mg
R /R shall not exceed 0,90.
eg mg
Additional requirements related to tubes for use with embrittling gases are given in Clause 12.
NOTE 1 It is generally assumed that p = 1,5p for compressed gases for tubes designed and manufactured to
h w
conform with this International Standard.
NOTE 2 For some applications such as tubes assembled in batteries to equip trailers or skids (ISO modules) or
MEGCs for the transportation and distribution of gases, it is important that stresses associated with mounting the
tube (e.g. bending stresses, see Annex F, torsional stresses, dynamic loadings etc.) are considered by the assembly
manufacturer and the tube manufacturer.
NOTE 3 In addition, during hydraulic pressure testing, tubes could be supported or lifted by their necks;
therefore, it can be necessary to consider potential bending stresses. For general guidance, see Annex F.
7.2 Design of tube ends
Tube ends shall be approximately hemispherical with thickness not less than the calculated minimum
wall thickness, a. The dimensions of the tube end profiles shall be specified for each design, taking into
consideration the stress distribution and the manufacturing process.
To permit internal visual inspection of the tube, an adequate opening shall be provided at the neck ends.
The nominal diameter of the opening shall be greater than D/12. However, internal diameters of neck
openings may be smaller provided appropriate tools are used to perform the visual inspection, i.e. bore
scope, mirrors, high intensity lighting, etc.
When the tube ends are threaded, the thickness at the thread root shall be sufficient to take into account
the developed stress in this part.
NOTE Stress analysis should be carried out to ensure that design limits are not exceeded.
6 © ISO 2015 – All rights reserved

ISO 11120:2015(E)
7.3 Design drawing
A fully dimensioned drawing shall be prepared which includes the specification of the material such as
heat treatment details, guaranteed mechanical properties and mass of the tube.
8 Construction and workmanship
8.1 General
The tube shall be manufactured from seamless steel tubing, typically hot rolled, extended/extruded or
forged. The ends shall be hot formed using either forging or spinning methods.
Metal shall not be added in the process of closure of the end.
Defects shall not be repaired by welding.
8.2 Surface imperfections
The internal and external surfaces of the finished tube shall be free from imperfections which could
adversely affect the safe working of the tube.
NOTE See Annex C for examples of imperfections and guidance on their evaluation.
The machined surfaces of the neck shall be inspected with a non-destructive examination method
acceptable to the Inspection Body, such as magnetic particle inspection (see ISO 10893-5), dye penetrant
methods (see ISO 10893-4), eddy current (see ISO 10893-2), etc., to ensure that they are free from
imperfections.
8.3 Ultrasonic examination
After completion of the final heat treatment and any operation resulting in loss of wall thickness (e.g.
grinding or machining), each tube shall be ultrasonically examined for internal and external defects and
laminar imperfections and to determine wall thickness in accordance with Annex B.
An ultrasonic examination for imperfections and wall thickness, in accordance with Annex B, shall also
be carried out on the supplied tubing.
The wall thickness at any point shall be not less than the guaranteed minimum thickness.
8.4 End closure (fitting)
Closure of the finished tube shall be accomplished by a method other than welding, brazing or braze
welding, and shall prevent leakage.
8.5 Dimensional tolerances
8.5.1 Out-of-roundness
The out-of-roundness of the cylindrical shell, i.e. the difference between the maximum and minimum
outside diameters at the same cross-section, shall not exceed 2 % of the mean value of these diameters
measured at least at the quarter and mid-length locations on the tube.
8.5.2 Outside diameter
The mean outside diameter shall not deviate by more than ±1 % from the nominal outside diameter; this
shall be verified at the quarter and mid-length locations on the tube.
ISO 11120:2015(E)
8.5.3 Straightness
The maximum deviation of the cylindrical part of the shell from a straight line parallel to the tube axis
shall not exceed 0,003 times the full body length, with the exception of stand-alone applications (where
tubes are not in close proximity to each other) where this value may be exceeded with written agreement
of the involved parties (customer, manufacturer and Inspection Body). See Figure 1.
Key
a maximum deviation 0,003 ⋅ L
L full parallel body length
Figure 1 — Illustration of deviation from a straight line
8.5.4 Eccentricity
The values of the minimum and maximum thicknesses shall not differ by more than 12,5 % from the
mean value of these two thicknesses; this shall be verified at least at the quarter and mid-length locations
on the tubes.
8.5.5 Length
The tolerance on the design overall length of the tube only, excluding fittings, shall not exceed the lesser
of ±1,5 % or ±50 mm, except that, for large tubes, >2 000 l, these values can be exceeded with written
agreement of the involved parties (customer, manufacturer and Inspection Body).
8.5.6 Water capacity
+10
The tolerance on the design water c
...