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, 
Having  regard  to  the  Treaty  establishing  the 
European  Economic  Community,  and  in particular 
Article  100  thereof; 
Having  regard  to the proposal  from  the Commission; 
Having  regard  to the  Opinion  of the  European 
Parliament; 
Having  regard  to the Opinion  of the Economic  and 
Social  Committee; 
Whereas  in the Member  States  the construction  and 
methods  of control  of gas  cylinders  are  subject  to 
mandatory  provisions  which  differ  from  one Member 
State  to another  and  consequently  hinder  trade  in 
such  cylinders;  whereas  it is therefore  necessary  to 
approximate  these  provisions; 
Whereas  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  lays 
down  in particular  the procedures  of EEC  approval 
and verification  for  these  vessels;  whereas,  in 
accordance  with  that  Directive,  the  technical 
requirements  to be satisfied  by EEC  type  seamless 
aluminium  alloy  gas  cylinders  of 0-2  to 150  litres 
capacity  should  be laid  down,  so that  these  cylinders 
can be freely  put into  circulation,  marketed  and  used, 
after  they  have  undergone  the proposed  controls  and 
have  been  given  the proposed  marks  and  symbols, 
HAS  ADOPTED  THIS  DIRECTIVE: 
Article  1 
1. This  Directive  applies  to the  stress-resistant 
shells  of refillable  seamless  aluminium  alloy  gas 
cylinders  (i.e.,  formed  from  a single  piece),  of a 
capacity  of 0-2 to 150  litres  inclusive  and  designed  to 
contain  compressed,  liquified  or dissolved  gases,  the 
effective  pressure  of which  is greater  than  1 bar gauge 
at a temperature  of 15  °C. These  seamless  gas 
cylinders  are hereinafter  termed  'cylinders'. 
2. The  provision  of this  Directive  shall  not  apply 
to: 
— cylinders  manufactured  from  an aluminium  alloy 
with  a tensile  strength  greater  than  500  N/mm2; — cylinders  which  have  been  manufactured  by a 
method  involving  the addition  of metal  during  the 
process  of sealing  the bottom  end. 
Article  2 
Cylinders  which  conform  to the  requirements  laid 
down  in the  Annex  to this  Directive  shall  be 
EEC-type  cylinders. 
Article  3 
No Member  State  may,  for reasons  connected  with 
constructions  or controls,  refuse,  prohibit  or restrict 
the placing  on the market  and  entry  into  appropriate 
service  of EEC-type  cylinders  bearing  the  EEC 
approval  symbol  and  the  EEC  inspection  mark, 
provided  that  the provisions  of Article  4 are complied 
with. 
Article  4 
EEC-type  cylinders  shall  be subject  to: 
(a) EEC  approval  when  their  hydraulic  test  pressure 
is not greater  than  225  bars  and  if their  capacity 
is not less  than  0-2 litres  and  not more  than  one 
litre; 
(b) EEC  approval  and  EEC  inspection 
(i) when  their  hydraulic  test  pressure  is not 
greater  than  225  bars  and  if their  capacity  is 
more  than  one  litre  and  not  more  than  150 
litres; 
(ii) when  their  hydraulic  test  pressure  is greater 
than 225  bars,  irrespective  of their  capacity. 
Article  5 
1. Member  States  shall  put  into  force  the laws, 
regulations  and  administrative  provisions  needed  in 
order  to comply  with  this  Directive  within  18 months 
of its notification  and  shall  forthwith  inform  the 
Commission  thereof. 
2. Member  States  shall  ensure  that  the text  of the 
main  provisions  of national  law  which  they  adopt  in 
the field  covered  by this  Directive  are communicated 
to the Commission. 
Article  6 
This  Directive  is addressed  to the Member  States. 
No C 104/76 Official  Journal  of the European  Communities 13. 9. 74 
ANNEX  I 
1. TERMS  AND  SYMBOLS  USED  IN THIS  ANNEX 
1.1. Yield  stress 
The 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 bars; 
Pr =  relative  cylinder  bursting  pressure  measured  in the bursting  test,  in bars; 
Re —  minimum  value  of the  yield  stress  (Rp  0-2)  guaranteed  by the cylinder  manu-
facturer,  in N/mm2; 
Rm  = minimum  tensile  strength  guaranteed  by the cylinder  manufacturer  in N/mm2; 
a =  minimum  thickness  of the  wall  of the  cylindrical  part  of the  cylinder,  in mm; 
D =  maximum  outside  diameter  of the  cylinder,  in mm; 
Rt =  actual  tensile  strength,  in N/mm2; 
d =  diameter  of the former  for the bend  test. 
2. TECHNICAL  REQUIREMENTS 
2.1. Materials 
2.1.1.  The  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: 
Type  of alloy Chemical  composition 
Type  of alloy 
Cu Mg Si Fe Mn Zn Cr Ti+Zr 
(a) 
Al-Mg  3 Mn min. 
max. 0-10 2-4 
3-8 0-5 0-5 0-3 
1-0 0-2 0-25 0-2 
(b) 
Al-Mg  4*5 Mn min. 
max. 0-10 4-0 
5-1 0-5 0-5 0-3 
1-0 0-2 0-25 0-2 
.(c) 
Al-Si  1 Mg min. 
max. 0-10 0-4 
1-4 0-6 
1-6 0-5 0-4 
1-0 0-2 0-35 0-2 
(d) 
Al-Cu-Mg min. 
max. 5-2 
6-0 0-2 
0-4 0-2 0-3 0-15 
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. 
13. 9. 74 Official  Journal  of the European  Communities No 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 Re 
TT+Ph 
The value  of Re  shown  in the formula  shall  in no case  be greater  than  0-85  Rm 
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. 
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  L0  = 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 
Rt in N/mm2 Value  of n 
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. 
13. 9. 74 Official  Journal  of the European  Communities No 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. 
No 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. 
13. 9. 74 Official  Journal  of the European  Communities No 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. 
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 Re  in N/mm2  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 25 ....6-851 
10-4/40-5 
13.9.74 Official  Journal  of the European  Communities No C 104/83 
a ^ .bp u \ 
No C 104/84 Official  Journal  of the  European  Communities 13. 9. 74 
ANNEX  11 
CORROSION  TESTS 
I. TESTS  TO EVALUATE  SENSITIVITY  TO  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, bl b2 b3 b4, al a2 b2 bl, a4 a3 b3 b4 are all sawn  with  a 
band  saw  and  then  carefully  trimmed  with  a fine  file.  The  surfaces  al a4 b4 bl 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 
HN03  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  cm3, 
H20:  929  cm3. 
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). 
13. 9.74 Official  Journal  of the European  Communities No C 104/85 
2. PERFORMANCE  OF TEST 
2.1. Two  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.  Titration  of hydrogen  peroxide 
Since  hydrogen  peroxide  is not very  stable,  it is essential  to titrate  it before  use.  This  is 
done  as follows. 
Take  10 cm3  of hydrogen  peroxide  with  a pipette,  dilute  to 1 000 cm3  (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 cm3  of the hydrogen  peroxide  solution  C, 
— about  2 cm3  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.  Explanation  of titration 
The reaction  of the permanganate  on the hydrogen  peroxide  in a sulphuric  medium  is 
expressed  as: 
2 KMn04  + 5 H202  + 3 H2  S04  K2  S04  + 2 Mn  S04  + 8H20  + 5 Oz 
which  gives  the equivalence:  316  g KMn04  ^ 170  g H2Oa. 
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 cm3  of the test 
sample  represent  0-1 cm3  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.  Preparation  of the  solution 
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 H202  per  litre,  the volume  required, 
expressed  in cubic  centimetres,  will  be: 
1 000  X 30 
T 
No C 104/86 Official  Journal  of the European  Communities 13. 9. 74 
2.2.2. 
2.2.2.1 
2.2.2.2. 
2.3. 
2.3.1. 
2.3.2. 
2.3.3. 
3. 
3.1. Solution  B 
Products  required: 
NaCl,  crystallized,  for analysis 
HC1,  pure  concentrated,  37%  HCl 
Deionized  water. 
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. 
Etching  conditions 
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 cm3  per cm2  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. 
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. 
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/cm2  is 10 :1 (see  2.3.1). 
PREPARATION  OF SPECIMENS  FOR  EXAMINATION 
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 
Hardener  HY  951 or equivalent 
13. 9. 74 Official  Journal  of the  European  Communities No 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  al 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. 
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. 
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  TO  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. 4. MICROGRAPHIC  EXAMINATION  OF SPECIMENS 
5. INTERPRETATION  OF MICROGRAPHIC  EXAMINATION 
No C 104/88 Official  Journal  of the European  Communities 13. 9. 74 
Figure  1 
13. 9. 74 Official  Journal  of the  European  Communities No 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 
20 mm 
Figure  3 
Outlet  pipe 
a'2 
a'3 
Specimen  of the cylinder 
a'4 
Araidite 
No 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) 
13. 9. 74 Official  Journal  of the  European  Communities No 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  No. 
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)