CELEX: 51974PC0966
Language: en
Date: 1974-07-04
Title: PROPOSAL FOR A COUNCIL DIRECTIVE ON THE APPROXIMATION OF THE LAWS OF THE MEMBER STATES RELATING TO SEAMLESS ALUMINIUM ALLOY GAS CYLINDERS

13. 9. 74                          Official Journal of the European Communities                            No C 104/75
              Proposal for a Council Directive on the approximation of the laws of the Member States
                                   relating to seamless aluminium alloy gas cylinders
                            (Submitted to the Council by the Commission on 18 July 1974)
 THE COUNCIL OF THE EUROPEAN COMMUNITIES,                      — cylinders which have been manufactured by a
                                                                   method involving the addition of metal during the
 Having regard to the Treaty establishing the                      process of sealing the bottom end.
 European Economic Community, and in particular
 Article 100 thereof;
                                                                                        Article 2
Having regard to the proposal from the Commission;
                                                               Cylinders which conform to the requirements laid
Having regard to the Opinion of the European                   down in the Annex to this Directive shall be
Parliament;                                                    EEC-type cylinders.
Having regard to the Opinion of the Economic and
 Social Committee;                                                                      Article 3
                                                               No Member State may, for reasons connected with
Whereas in the Member States the construction and              constructions or controls, refuse, prohibit or restrict
methods of control of gas cylinders are subject to             the placing on the market and entry into appropriate
mandatory provisions which differ from one Member              service of EEC-type cylinders bearing the EEC
State to another and consequently hinder trade in              approval symbol and the EEC inspection mark,
such cylinders; whereas it is therefore necessary to           provided that the provisions of Article 4 are complied
approximate these provisions;                                  with.
Whereas the Council Directive of . . . on the
approximation of the laws of the Member States                                          Article 4
relating to common provisions on pressure vessels              EEC-type cylinders shall be subject to:
and to the methods of control of these vessels lays
down in particular the procedures of EEC approval              (a) EEC approval when their hydraulic test pressure
and verification for these vessels; whereas, in                     is not greater than 225 bars and if their capacity
accordance with that Directive, the technical                       is not less than 0-2 litres and not more than one
requirements to be satisfied by EEC type seamless                   litre;
 aluminium alloy gas cylinders of 0-2 to 150 litres
capacity should be laid down, so that these cylinders          (b) EEC approval and EEC inspection
can be freely put into circulation, marketed and used,                (i) when their hydraulic test pressure is not
after they have undergone the proposed controls and                       greater than 225 bars and if their capacity is
have been given the proposed marks and symbols,                           more than one litre and not more than 150
                                                                          litres;
                                                                    (ii) when their hydraulic test pressure is greater
HAS ADOPTED THIS DIRECTIVE:
                                                                          than 225 bars, irrespective of their capacity.
                        Article 1                                                       Article 5
1.    This Directive applies to the stress-resistant           1.     Member States shall put into force the laws,
shells of refillable seamless aluminium alloy gas              regulations and administrative provisions needed in
cylinders (i.e., formed from a single piece), of a             order to comply with this Directive within 18 months
capacity of 0-2 to 150 litres inclusive and designed to        of its notification and shall forthwith inform the
contain compressed, liquified or dissolved gases, the          Commission thereof.
effective pressure of which is greater than 1 bar gauge
                                                               2.     Member States shall ensure that the text of the
at a temperature of 15 °C. These seamless gas
                                                               main provisions of national law which they adopt in
cylinders are hereinafter termed 'cylinders'.                  the field covered by this Directive are communicated
2.    The provision of this Directive shall not apply          to the Commission.
to:
                                                                                        Article 6
— cylinders manufactured from an aluminium alloy
    with a tensile strength greater than 500 N/mm 2 ;          This Directive is addressed to the Member States.
 ---pagebreak--- No C 104/76                      Official Journal of the European Communities                                   13. 9. 74
                                                         ANNEX    I
           1.     T E R M S A N D SYMBOLS USED IN T H I S A N N E X
           1.1.   Yield stress
                  T h e term 'yield stress' means the conventional yield stress (Rp 0-2) i.e. the value of the
                  stress (a) which gives rise to a non-proportional elongation to 0-2% of the gauge length
                  of the test-piece.
           1.2.   The symbols used in this Annex have the following meanings:
                  Ph    = relative hydraulic test pressure (design pressure), in b a r s ;
                  Pr     = relative cylinder bursting pressure measured in the bursting test, in b a r s ;
                  Re    — minimum value of the yield stress (Rp 0-2) guaranteed by the cylinder manu-
                            facturer, in N / m m 2 ;
                  Rm     = minimum tensile strength guaranteed by the cylinder manufacturer in N / m m 2 ;
                  a      = minimum thickness of the wall of the cylindrical p a r t of the cylinder, in m m ;
                  D      = m a x i m u m outside diameter of the cylinder, in m m ;
                  Rt    = actual tensile strength, in N / m m 2 ;
                  d     = diameter of the former for the bend test.
          2.      TECHNICAL REQUIREMENTS
          2.1.    Materials
          2.1.1.  T h e materials used for the manufacture of the cylinders shall be aluminium alloys
                  which, after the proposed heat treatment, are sufficiently resistant to atmospheric
                  corrosion.
           2.1.2. Aluminium alloys with the following chemical compositions are acceptable for the
                  manufacture of gas cylinders:
                                                                        Chemical composition
                           Type of alloy
                                                     Cu     Mg       Si     Fe      Mn       Zn    Cr    Ti+Zr
                    (a)
                                          min.              2-4                     0-3
                    Al-Mg 3 M n
                                          max.       0-10   3-8     0-5    0-5      1-0      0-2  0-25     0-2
                    (b)
                                          min.              4-0                     0-3
                    Al-Mg 4*5 M n
                                          max.       0-10   5-1     0-5    0-5      1-0      0-2  0-25     0-2
                   .(c)
                                          min.              0-4     0-6             0-4
                    Al-Si 1 M g
                                          max.       0-10   1-4     1-6    0-5      1-0      0-2  0-35     0-2
                    (d)
                                          min.       5-2    0-2                     0-15
                    Al-Cu-Mg
                                          max.       6-0    0-4     0-2    0-3      0-35     0-10 0-10     0-25
                  For the interpretation of the results of the chemical analysis of these alloys, reference
                  shall be made to the ISO recommendation R 209-1971, page 4.
 ---pagebreak--- 13. 9. 74                       Official Journal of the European Communities                              N o C 104/77
          2.1.3. Any other aluminium alloy may be used for the manufacture of gas cylinders provided
                 that it first passes the atmospheric corrosion resistance tests described in Annex II to
                 this Directive or, failing this, complies with a specification laid down by the Committee
                 for Adaption to Technical Progress referred to in Article 19 of the Council Directive
                 of         on the approximation of the laws of the Member States relating to common
                 provision on pressure vessels and to the methods of control of these vessels.
          2.1.4. The cylinder manufacturer shall obtain and provide cast analysis certificates for the
                 aluminium alloys supplied for the manufacture of the cylinders.
          2.1.5. The inspection authority shall have the opportunity of making independent analyses.
                 These analyses shall be carried out either on specimens of the alloy taken at the time
                 of casting such as those supplied by the alloy manufacturers to the cylinder manu-
                 facturer or on the finished cylinders.
          2.2.   Heat and Mechanical Treatments
                 The manufacturer shall state the type of manufacture: cold working, type of heat
                 treatment (temperature and duration) and type of cooling.
          2.3.   Calculation of the Parts under Pressure
          2.3.1. The thickness of the cylinder walls shall not at any point be less than that calculated
                 for the cylindrical part by the formula:
                                                         Ph'D
                                                    a =
                                                          20 R e
                                                          T T +  P h
                 The value of R e shown in the formula shall in no case be greater than 0-85 R m
                 whatever the type of alloy used.
          2.3.2. The minimum wall thickness shall not in any case be less than 1*5, 2 and 3 mm
                 respectively for cylinder diameters of 50 mm or less, greater than 50 and less than
                 150 mm, and 150 mm or more.
          2.3.3. The thickness and the shape of the bottom and the top end shall be such as to
                 satisfy the requirements of the tests provided for in item 3.2 (bursting test) and 3.3
                 (pressure cycling test) of this Annex.
          2.3.4. In order to obtain a satisfactory stress distribution, the thickness of the cylinder walls
                 shall increase progressively in the transition part situated between the cylindrical part
                 and the end; the wall shall be free from defects.
          2.4.   Construction and workmanship
          2.4.1. Each cylinder shall be examined for thickness and for external and internal surface
                 defects:
                 — the wall thickness shall not at any point be less than that specified on the drawing;
                 — the internal and external surface of the cylinder shall be free from defects which
                     would adversely affect the safe use of the cylinder.
          2.4.2. The out-of-roundness of the cylindrical shell shall be limited to such a value that the
                 difference between the maximum and minimum outside diameters in the same cross
                 section is not more than 2 % of the average of these diameters.
          2.4.3. When a footring is provided, it shall be sufficiently strong and made of a material
                 compatible with that of the cylinder. The shape should preferably be cylindrical and
                 shall give the cylinder sufficient stability. The footring shall not allow water to
                 accumulate or permit ingress of water between the footring and the cylinder.
 ---pagebreak--- No C 104/78                         Official Journal of the European Communities                                13. 9. 74
           3.         TESTS
           3.1.       Mechanical Tests
           3.1.1.     General requirements
                      All the mechanical tests for checking the properties of the alloy of gas cylinders shall
                      be carried out on test pieces taken from the finished cylinders.
           3.1.2.      Types of tests and evaluation of test results
                      Every test cylinder shall undergo one tensile test in a longitudinal direction and four
                      band tests in a circumferential direction.
           3.1.2.1.   Tensile test
          3.1.2.1.1. The tensile test shall be carried out on a test specimen of the type shown in Fig. 1
                      of this Annex with a gauge length L 0 = 5-65 y F, F being the right cross-section of
                     the test piece. The two faces of the test piece representing the inside and outside
                      surfaces of the cylinder shall not be machined.
          3.1.2.1.2. The elongation in percent shall not be less than:
                     — 12% for the alloys referred to in (a), (b) and (c) of the table in item 2.1.2 and for
                          the alloys subject to the requirements in 2.1.3;
                     — 10% for the alloys referred to in (d) of the table in item 2.1.2.
          3.1.2.2.    Bend test
          3.1 2.2.1. The bend test shall be carried out on specimens obtained by cutting into two equal
                     parts a ring of width 3a; in no case may the width of the test piece be less than 25 mm.
                     Each strip may be machined only on the edges.
          3.1.2.2.2. The bend test shall be carried out by means of a former of diameter d and two
                     cylinders separated by a distance of d + 3a. During the test, the inside face of the ring
                     shall be placed against the former.
          3.1.2.2.3. The test piece shall remain uncracked when bent inwards around the former until the
                     interior edges are separated by a distance not greater than the diameter of the former.
          3.1.2.2.4. The ratio (n) between the diameter of the former and the thickness of the test piece
                     shall conform to the values given in the following table:
                                            Actual tensile strength
                                                                                             Value of n
                                                 Rt in N / m m 2
                              up to 330 inclusive                                               6
                     above 330 to 400 inclusive                                                 7
                     above 400 to 500 inclusive                                                 8
          3.2.       Bursting test under hydraulic pressure
          3.2.1.     Test conditions
          3.2.1.1.   The bursting test under hydraulic pressure shall be carried out in two successive stages
                     by means of an apparatus such that the pressure in the cylinder increases regularly
                     until the cylinder bursts and that the curve of the pressure variation with time is
                     recorded.
          3.2.1.2.   During the first stage, the rate of pressure increase until the point at which plastic de-
                     formation begins shall be about 1 bar/s.
 ---pagebreak--- 13. 9. 74                           Official Journal of the European Communities                              N o C 104/79
                     From that point, (second stage) the pumping rate shall be increased to four times that
                     of the first stage and kept constant until the cylinder bursts.
           3.2.2.   Performatice of test
                     The bursting test under hydraulic pressure shall afford:
                     — an examination of the pressure/time curve, in order to determine the pressure at
                         which plastic deformation of the cylinder commences, the bursting pressure and
                         the deformation of the cylinder during the test;
                    — an examination of the fracture and the shape of its edges.
           3.2.3.    Test acceptance conditions
           3.2.3.1. The pressure corresponding to the initiation of plastic deformation shall not be less than
                     four-thirds of the hydraulic test pressure.
          3.2.3.2.  The measured bursting pressure (Pr) shall not be less than five-thirds of the test
                    pressure (Ph)-
          3.2.3.3.  The bursting test shall not cause any fragmentation of the cylinder.
          3.2.3.4.  The main fracture shall not show any signs of brittleness i.e., the edges of the fracture
                    shall not be radial but shall be sloped in relation to a diametrical plane and shall
                    show signs of striction throughout their thickness.
          3.2.3.5.  The fracture shall not reveal a characterized defect in the metal.
          3.2.3.6.  The fracture shall begin and develop in the cylindrical part and shall not extend into
                    either end of the cylinder.
          3.2.4.    Data which may help in the interpretation of the test
          3.2.4.1.  The measurement of the volume of water used from the start of the pressure build-
                    up to the moment of bursting, this gives an indication as to the volumetric expansion
                    of the cylinder.
          3.2.4.2.  The measurement of the increase in the circumference of the cylinder in the area of
                    the fracture.
          3.3.      Pressure cycling test
          3.3.1.    The pressure cycling test shall be carried out on two cylinders, which are guaranteed
                    by the manufacturer to be reasonably representative of the minimum thickness values
                    envisaged in the design, using a non-corrosive fluid.
          3.3.2.    The test shall be carried out by subjecting the cylinder to successive reversals of
                    hydraulic pressure between the initial or residual pressure and the pressure known as
                    the test pressure.
                    The test parameters shall satisfy either one or the other of the following conditions,
                    the choice being left to the Member State:
                    (1) — total number cycles: 80 000,
                         — test pressure:          2/3 Ph + residual pressure,
                         — frequency:              15 cycles/minute;                            '
                    (2) — total number cycles: 15 000,
                         — test pressure:          Ph + residual pressure,
                         — frequency:              5 cycles/minute.
                    The residual pressure (the pressure at the end of the cylinder decompression phase)
                    shall not exceed 5 % of the value of the test pressure.
                    The temperature measured on the outside wall of the cylinder shall not exceed 50°C
                    during the test.
          3.3.3.    No fracture shall occur during the test.
 ---pagebreak--- N o C 104/80                   Official Journal of the European Communities                                  13. 9. 74
           3.4.   Hydraulic test
           3.4.1. The value of the hydraulic pressure test shall be equal to the design pressure (Ph).
           3.4.2. The water pressure in the cylinder shall increase regularly until the test pressure is
                  reached.
           3.4.3. The cylinder shall remain under the test pressure for a time sufficiently long to
                  demonstrate that the pressure shows no tendency to fall and that leaktightness has
                  been achieved.
           3.4.4. Any cylinder which does not satisfy these test requirements shall be rejected.
           4.     EEC APPROVAL
           4.1.   The applicant for approval shall submit the documentation necessary for the verification
                  prescribed below, together with a number not exceeding eight prototype cylinders,
                  fully representative of future production, which may be necessary for carrying out the
                  tests prescribed below, and any additional information required by the Member State.
           4.2.   In the course of the EEC approval process, the Member State shall:
                  — verify that the calculations provided for in item 2.3 are correct;
                  — verify that the conditions laid down in items 2.1 and 2.2 are satisfied;
                  — perform on the cylinders submitted as prototypes:
                      — the tests provided for in item 3.1.2 except in respect of the number of tensile
                          tests, three of these tests being required,
                      — the test provided for in item 3.2, on two cylinders,
                      — the test provided for in item 3.3, on two cylinders, except where only the length
                          parameter of the cylinder differs and is situated in the range of lengths of the
                          types of cylinders which have already been approved;
                  — issue the EEC approval certificate conforming to the model in Annex III to this
                      Directive.
           5.     EEC INSPECTION
           5.1.   For the purpose of EEC inspection the cylinder manufacturer shall:
           5.1.1. make available to the inspection authority:
                  — the EEC approval certificate,
                  — the analysis certificates of the aluminium alloys supplied for the manufacture of_the
                      cylinders and when the cylinder is manufactured with the alloy referred to in (d)
                      of the table in item 2.1.2 the results of intercrystalline corrosion tests carried out
                      according to one of the methods described in section 1 in Annex II to this Directive,
                      on test pieces taken from one cylinder of each tempering charge,
                  — the means of identifying the aluminium alloy cast from which each cylinder is
                      manufactured,
                  — the documents necessary to certify that the cylinders submitted for EEC inspection
                      have undergone the same heat treatment as those submitted for the approval
                      procedure,
                  — the list of cylinders stating the numbers and the marks provided for in item 6.
 ---pagebreak--- 13. 9. 74                         Official Journal of the European Communities                                N o C 104/81
           5.2.     In the EEC inspection
           5.2.1.   The control authority shall:
                    — ascertain that approval has been obtained and that the cylinders conform to this
                        approval,
                    — check the documents which give the data concerning the materials,
                    — ascertain whether the technical requirements set out in section 2 have been met,
                        and verify in particular, by an external and internal visual examination of a sample
                        number of between 5 and 10% of the cylinders in each batch whether the con-
                        struction and the examination carried out by the manufacturer in accordance with
                        item 2.4.1 are satisfactory,
                    — be present at the tests prescribed in items 3.1 and 3.2 and check the way they
                        are carried out,
                    — ascertain whether the information supplied by the manufacturer in the list in item
                        5.1.1 (fifth indent) is correct. Between 5 and 10% of the cylinders in each batch
                        shall be subjected to this check,
                   — issue the EEC inspection certificate conforming to the model in Annex IV to this
                       Directive.
           5.2.2.  For the execution of the two types of tests prescribed in items 3.1 and 3.2, two cylinders
                   shall be taken at random from each batch of 402 cylinders made from the same cast
                   and having been subjected to the same heat treatment and from each remaining batch
                   of less than 402 cylinders.
                   One of the two cylinders shall be subjected to the tests prescribed in item 3.1 (mecha-
                   nical tests) and the other to the test prescribed in item 3.2 (bursting test).
                   If one of the tests fails even partially to give satisfaction, two further cylinders
                   shall be taken at random from the same batch and subjected to the type of test which
                   was failed.
                   If either of these two further cylinders fails to give satisfaction, all the cylinders of
                   that batch shall be rejected unconditionally.
          5.2.3.   The selection of specimens and all the tests shall be carried out in the presence of a
                   representative of the inspection authority.
          5.2.4.   All the cylinders in the batch shall be subjected to a hydraulic test as specified in item
                   3.4 in the presence and under the supervision of a representative of the inspection
                   authority.
          5.3.    Exemption from EEC inspection
                   For the cylinders referred to in Article 4 (a), of this Directive and in accordance with
                  Article 15 (a), of the Council Directive of            on the approximation of the laws
                   of the Member States relating to common provisions on pressure vessels and to the
                   methods of control of these vessels, the manufacturer shall carry out, on his own
                  responsibility, all the test and inspection operations prescribed in item 5.2.
                  The manufacturer shall provide the inspection authority with all the documents and
                  the test and control reports.
                  The presence of a representative of the inspection authority (cf. items 5.2.3 and 5.2.4
                  of this Annex) shall not be required.
          6.      MARKING
          6.1.    When all the prescribed checks have been carried out by the inspection authority, and
                  providing that the results are satisfactory, the inspection authority shall issue a certi-
                  ficate stating the checks which have been carried out.
          6.2.    The markings shall be grouped together and none may be stamped on the stress-
                  resistant shell of the cylinder.
 ---pagebreak--- No C 104/82                     Official Journal of the European Communities                            13. 9. 74
          6.3.    A symbol shall be stamped on the metal of the top end of each cylinder or on an
                  identification plate, if any, of a minimum thickness of 3 mm; the symbol referred to
                  in item 5.3 of Annex I to the Council Directive of             on the approximation
                  of the laws of the Member States relating to common provisions on pressure
                  vessels and to the methods of testing these vessels shall be used for the cylinder's
                  referred to in Article 4 (a) of this Directive, and the symbol of EEC type approval
                   '(£)' referred to in Annex I item 5.1, followed by the symbol of EEC inspection
                        referred to in Annex II item 3.1.1.1 (a) of the abovementioned Directive
                  shall be used for the cylinders referred to in Article 4 (b) of this Directive. These
                  symbols shall be followed by the following markings:
          6.4.   Markings relating to the construction
          6.4.1. In respect of the metal
                 A number indicating the value of R e in N/mm 2 on which the calculation was based.
          6.4.2. In respect of the hydraulic test
                 The value of the test pressure in bars in figures larger than the others and above
                 them, the date (month and year) of the first hydraulic test.
          6.4.3. In respect of the type of cylinder
                 Below the figure relating to the test pressure, the weight of the cylinder in kg,
                 without the valve and tap, and the minimum capacity in litres guaranteed by the
                 cylinder manufacturer.
                 The weight and the capacity shall be expressed to three significant figures, the third
                 one being fixed 'by rounding down' for the capacity and 'rounding up' for the weight.
          6.4.4. In respect of the origin
                 The manufacturer's mark and the serial number.
          6.4.5. Example:
                                                      04/72
                                           £ e 270 2 2 5       ....6-851
                                                     10-4/40-5
 ---pagebreak--- 13.9.74       Official Journal of the European Communities No C 104/83
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 ---pagebreak--- N o C 104/84                         Official Journal of the European Communities                             13. 9. 74
                                                          ANNEX   11
                                                    CORROSION TESTS
                  I. TESTS T O EVALUATE SENSITIVITY T O INTERCRYSTALLINE CORROSION
            The method described below consists of immersing the specimens taken from the cylinder under
            test in two different corrosive solutions at the same time, examining them after a specified
            etching time for any signs of intercrystalline corrosion and determining the type and intensity
            of such corrosion. The propagation of intercrystalline corrosion is determined metallographically
            on polished surfaces cut transversely to the etched surface.
            1.1.       Sampling
                       Specimens are taken from the pointed top, the body and the bottom of the cylinder
                       (Fig. 1), so that the tests with solution A defined in 2.1.1 and solution B defined in
                       2.1.2 can be carried out on metal from three parts of the cylinder.
                       A sufficient number of specimens must be taken to meet the requirements set out in
                       2.2.1 and 2.2.2.
                       Each specimen must be of the general form and the dimensions given in Fig. 2.
                       The faces al a2 a3 a4, b l b2 b3 b4, a l a2 b2 b l , a4 a3 b3 b4 are all sawn with a
                       band saw and then carefully trimmed with a fine file. The surfaces a l a4 b4 b l and
                       a2 a3 b3 b2 which correspond respectively to the inner and outer faces of the cylinder
                       are left in their original rough state.
            1.2.       Preparation of surface before corrosive etching
             1.2.1.    Products required
                       H N 0 3 for analysis, density 1-33
                       HF for analysis, density 1*14 (at 40%)
                       Deionized water                                                        '
             1.2.2.    Method
                       In a one-litre pyrex beaker, prepare the following solution:
                       HN03:      63 cm3,
                       HF:          6 cm 3 ,
                       H20:      929 cm 3 .
                       Heat the solution to 95 °C.
                       Dip each specimen suspended on an aluminium wire for one minute in this solution.
                       Then wash in running water followed by deionized water.
                       Immerse the specimen in nitric acid as defined in 1.2.1 above for one minute, at room
                       temperature, to remove any copper deposit which may have formed.
                       Rinse in deionized water.
                       To prevent oxidation of specimens, on completion of preparation they should be
                       plunged in the corrosion bath intended for them (see 2.2 below).
 ---pagebreak--- 13. 9.74                              Official Journal of the European Communities                            No C 104/85
         2.       PERFORMANCE OF TEST
         2.1.     T w o corrosive solutions are to be used, one with 57 g/1 sodium chloride and 3 g/1
                  hydrogen peroxide ( = solution A), and the other with 30 g/1 sodium chloride and
                  5 g/1 hydrochloric acid ( = solution B).
         2.2.     Preparation of corrosive solutions
         2.2.1.   Solution A
         2.2.1.1. Products Required
                  NaCl,                   crystallized, for analysis,
                  H202                    100-110 medicinal volumes,
                  KMn04                   for analysis,
                  H2S04                   for analysis, density 1*83,
                  Deionized water.
         2.2.1.2. T i t r a t i o n of h y d r o g e n p e r o x i d e
                  Since hydrogen peroxide is not very stable, it is essential to titrate it before use. This is
                  done as follows.
                  Take 10 cm 3 of hydrogen peroxide with a pipette, dilute to 1 000 cm 3 (in a gauged
                  flask) with deionized water, thus obtaining a hydrogen peroxide solution which will
                  be called C. With a pipette, place in an erlenmeyer flask:
                  — 10 cm 3 of the hydrogen peroxide solution C,
                  — about 2 cm 3 of sulphuric acid, density 1-83.
                  A solution of permanganate at 1-859 g/1 is used for the titration. The permanganate
                  itself serves as an indicator.
         2.2.1.3. E x p l a n a t i o n of t i t r a t i o n
                  The reaction of the permanganate on the hydrogen peroxide in a sulphuric medium is
                  expressed as:
                  2 K M n 0 4 + 5 H 2 0 2 + 3 H2 S04                  K2 S 0 4 + 2 Mn S 0 4 + 8 H 2 0 + 5 O z
                  which gives the equivalence: 316 g K M n 0 4 ^ 170 g H 2 O a .
                  Therefore 1 g of pure hydrogen peroxide reacts on 1-859 g of permanganate; hence
                  the use of a 1-859 g/1 solution of permanganate, which, volume for volume, saturates
                  1 g/1 of hydrogen peroxide.
                  Since the hydrogen peroxide was previously diluted 100 times, the 10 cm 3 of the test
                  sample represent 0-1 cm 3 of the original hydrogen peroxide.
                  By multiplying by 10 the number of cubic centimetres of permanganate solution used
                  for the titration, the titre T of the initial hydrogen peroxide in g/1 is obtained.
         2.2.1.4. P r e p a r a t i o n of t h e s o l u t i o n
                  Method for 10 1:
                  Dissolve 570 g of sodium chloride in deionized water to obtain a total volume of about
                  9 1. Add the quantity of hydrogen peroxide calculated below. Mix and then make up
                  the volume to 10 1 with deionized water.
                  Calculation of hydrogen peroxide volume to be placed in solution
                  Quantity of pure hydrogen peroxide required: 30 g.
                  If the hydrogen peroxide contains T grammes of H 2 0 2 per litre, the volume required,
                  expressed in cubic centimetres, will be:
                                                                     1 000 X 30
                                                                         T
 ---pagebreak--- No C 104/86                       Official Journal of the European Communities                             13. 9. 74
           2.2.2.    Solution B
           2.2.2.1   Products required:
                     NaCl, crystallized, for analysis
                     HC1, pure concentrated, 37% HCl
                     Deionized water.
           2.2.2.2. Preparation of the solution:
                     Method for 10 1:
                     Dissolve 300 g of sodium chloride and 50 g of HCl (50 g = 0 - 5%) in 9 1 of deionized
                     water, mix well and make up to 10 1.
          2.3.      Etching conditions
          2.3.1.    Etching in solution A
                    The corrosive solution is placed in a crystallizer (or possibly a large beaker) and
                    this in its turn is placed in a water bath. The water bath is stirred with a magnetic
                    stirrer and the temperature is regulated with a contact thermometer.
                    The specimen is either suspended in the corrosive solution by an aluminium wire or
                    placed in the solution so that it rests only on the corners, the second method being
                    preferable. The etching time is 6 hours and the temperature fixed at 30 ± 1°C. Care
                    should be taken to ensure that the quantity of reagent is at least 10 cm 3 per cm 2 of
                    specimen surface.
                    After etching, the specimen is washed in water, immersed for about 30 seconds in 50%
                    dilute nitric acid, washed again in water and dried by compressed air.
          2.3.2.    A number of specimens can be etched at the same time provided that they are of the
                    same type of alloy and that they are not in contact. The minimum quantity of reagent
                    per unit of specimen surface must, of course, be respected.
          2.3.3.    Etching in solution B
                    The corrosive solution is poured into a suitable glass container (e.g. a beaker). The
                    test is carried out at room temperature.While it is impossible to avoid variations in
                    room temperature during the test, it is preferable to carry out the test in the water
                    bath, the temperature of which is adjusted to 23 °C by a thermostat. Etching time is
                    72 hours.
                    The specimens are kept immersed in the corrosive solution in accordance with 2.3.1.
                    After etching, the specimens are very carefully washed with deionized water and dried
                    by compressed air free of grease. Care must be taken to see that the ratio quantity of
                    corrosive solution/specimen surface in ml/cm 2 is 10 :1 (see 2.3.1).
          3.        PREPARATION OF SPECIMENS FOR EXAMINATION
          3.1.      Products required
                    Casting dishes with, e.g., the following dimensions:
                    — external diameter:          40 mm,
                    — height:                     27 mm,
                    — wall thickness:             2-5 mm.
                    Araldite DCY 230
                                                  or equivalent
                    Hardener HY 951
 ---pagebreak--- 13. 9. 74                           Official J o u r n a l of the E u r o p e a n Communities                    N o C 104/87
          3.2.       Method
                     Each specimen is placcd vertically in a casting dish on its face al a2 a3 a4. Around it is
                     poured a mixture of Araldite DCY 230 and hardener HY 951 in the proportion 9 to 1.
                     The setting time is about 24 hours.
                     A certain amount of material is removed from the face al a2 a3 a4, preferably by lathe,
                     so that the section a ' l a'2 a'3 a'4 examined under the microscope cannot show
                     corrosion from the surface al a2 a3 a4. The distance between the faces a l a2 a3 a4 and
                     a ' l a'2 a'3 a'4, i.e. the thickness removed by the lathe, must be at least 2 mmj (Figs. 2
                     and 3).
                     The section for examination is polished mechanically with alumina first on paper and
                     then on felt.
          4.         MICROGRAPHIC EXAMINATION OF SPECIMENS
                      The examination consists of noting the intensity of intercrystalline corrosion round
                      the entire perimeter of the section. In so doing, account is taken of the properties
                      of the metal on the outer and inner surface of the cylinder and in the thickness
                      of it.
                      The section is first examined at low magnification (e.g., X40), in order to locate the
                      most corroded areas, and then at a higher magnification, usually about X300, in
                      order to assess the nature and extent of the corrosion.
          5.          INTERPRETATION OF MICROGRAPHIC EXAMINATION
                      It is verified that intercrystalline corrosion is superficial, i.e., that its depth does not
                      exceed three grains perpendicularly to the face examined.
                      However, it is permitted to exceed these values locally provided that they occur in not
                      more than four fields of examination at X 300 magnification.
           II. TESTS T O EVALUATE REDUCTION IN WALL THICKNESS AS A RESULT OF
                                                  CORROSION BY WEATHER
           The examination of corrosion behaviour must be completed by a test on finished cylinders
           and/or specimens from finished cylinders to expose them to the most corrosive weather likely
           to occur during the utilization of the cylinders.
           This test should permit the evaluation of any reduction in wall cylinders, during the cylinder's
           average life.
           The value so obtained must not exceed 0-2 mm. However, a reduction in thickness exceeding
           0-2 mm is allowed provided that an equivalent extra thickness is taken into consideration
           when the wall thickness of the cylinder resistant shell is calculated.
 ---pagebreak--- No C 104/88 Official Journal of the European Communities 13. 9. 74
                                Figure 1
 ---pagebreak--- 13. 9. 7 4                   Official Journal of the European C o m m u n i t i e s                     N o C 104/89
                                                 Figure 2
                                             a3                       a2
                                       a'3                  a'2                       Thickness of the cylinder
         Hole 0 = 3 mm
                                         a'4                  a'1
                              b2
       b3
       b4
                      2 0 mm
                                                 Figure 3
                                                                                                 Outlet pipe
                                                   a'2
                   a'3
                                                                                    Specimen of the cylinder
                     a'4
                                                                    Araidite
 ---pagebreak--- N o C 104/90                        Official Journal of the European Communities                                 13. 9. 74
                                                      ANNEX     III
                                            EEC APPROVAL CERTIFICATE
            Inspection authority:                                           Application of Council Directive
                                                                            No                 of
            Date:                                                           EEC approval code No
            Designation of cylinders:                                       Capacity:
            Manufacturer's name and address:
            The undersigned hereby declares that he has checked that the verifications, tests and inspections,
            laid down in point 4.2 of Annex I to Council Directive No                    of            have been
            carried out successfully.
                                                  — are
            Cylinders of the accepted design   •{             subject to EEC inspection
                                                  — are not
            General   remarks:  the drawing which was the subject of         approval is annexed hereto.
            Signed and certified this                        day of                           at
                                                                              (Signature and capacity)
 ---pagebreak--- 13. 9. 74                         Official Journal of the European Communities                             N o C 104/91
                                                     ANNEX IV
                                         EEC INSPECTION CERTIFICATE
          Inspection authority:                                        Application of Council Directive
                                                                       No                   of
                                                                       EEC approval code No
                                                                       EEC inspection code No.
          Date:                                                        Capacity:.
          Designation of cylinders:                                    Production batch N o .
          Name and address of the manufacturer:
          The undersigned hereby declares that he has checked that the verifications, tests and inspec-
          tions prescribed in Annex 1, Point 5.2 to Council Directive No            of            have been
          carried out successfully.
          Special remarks:
          General remarks:
          Signed and certified this                      day of                        at
                                                                         (Signature and capacity)