ISO 10462:2005
(Main)Gas cylinders — Transportable cylinders for dissolved acetylene — Periodic inspection and maintenance
Gas cylinders — Transportable cylinders for dissolved acetylene — Periodic inspection and maintenance
ISO 10462:2005 specifies requirements for the periodic inspection of seamless and welded cylinders manufactured from steel or aluminium alloys intended for the transport of acetylene in cylinders of water capacity up to 150 l and requirements for the periodic inspection and maintenance of acetylene cylinders, regardless of the method of manufacture of the shell.
Bouteilles à gaz — Bouteilles transportables pour acétylène dissous — Contrôles et entretien périodiques
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 10462
Second edition
2005-02-15
Gas cylinders — Transportable cylinders
for dissolved acetylene — Periodic
inspection and maintenance
Bouteilles à gaz — Bouteilles transportables pour acétylène dissous —
Contrôles et entretien périodiques
Reference number
ISO 10462:2005(E)
©
ISO 2005
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ISO 10462:2005(E)
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ISO 10462:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Intervals between periodic inspections. 3
5 Preparation of gas cylinder. 4
6 Inspection and maintenance. 5
7 Identification of contents . 8
8 Markings. 8
9 Records. 8
10 Rejection and rendering cylinders unserviceable. 9
11 Disposal of unserviceable cylinders. 9
Annex A (informative) Inspection periods . 10
Annex B (normative) Procedure to be adopted when de-valving and when it is suspected that a
cylinder valve is obstructed. 11
Annex C (normative) Description and evaluation of defects and conditions for rejection of
acetylene gas cylinders at time of visual inspection . 13
Annex D (informative) Tops of acetylene cylinders containing monolithic porous mass. 16
Annex E (informative) Illustration of cracks in the porous mass of an acetylene cylinder, and tools
and clearance gauges. 18
Annex F (informative) Inspection and maintenance of valves and their junctions:
recommended procedures. 20
Annex G (informative) Test date rings for gas cylinders. 21
Bibliography . 22
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ISO 10462:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 10462 was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 4,
Operational requirements for gas cylinders.
This second edition cancels and replaces the first edition (ISO 10462:1994), which has been technically
revised.
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ISO 10462:2005(E)
Introduction
Acetylene cylinders differ from all other cylinders transporting compressed or liquefied gases in that they
contain a porous mass and normally a solvent in which the acetylene stored is dissolved. However, for special
applications there is also a limited quantity of acetylene cylinders containing a porous mass and no solvent.
For the periodic inspection cycle, due regard is to be given to the different types of porous masses. The
remainder of this document should be read considering these differences.
The primary objective of the presence of the porous mass is to limit an acetylene decomposition, should it be
initiated, and thus prevent a cylinder incident. If some porous mass is missing or if a defect (e.g. a cavity,
crack or void of significant size) exists as a result of breakdown or subsidence of the porous mass, then the
decomposition could progress at a rate that could cause an explosion.
The requirements dealt with in this document are mainly those that are specific for acetylene cylinders; for
more general requirements related to the periodic inspection of gas cylinders, reference is made to the
relevant ISO documents.
The periodic inspection of acetylene cylinders is to be performed only by competent persons and, in those
jurisdictions requiring it, persons authorized by the regulatory authority.
Due to the presence of a porous mass in the cylinder, neither a hydraulic or pneumatic pressure test, nor a
visual inspection of the internal surface of the shell can be carried out.
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INTERNATIONAL STANDARD ISO 10462:2005(E)
Gas cylinders — Transportable cylinders for dissolved
acetylene — Periodic inspection and maintenance
1 Scope
This International Standard specifies the requirements for periodic inspection of seamless and welded
cylinders manufactured from steel or aluminium alloys intended for the transport of acetylene in cylinders of
water capacity up to 150 l and the requirements for the periodic inspection and maintenance of acetylene
cylinders, regardless of the method of manufacture of the shell.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3807-1:2000, Cylinders for acetylene — Basic requirements — Part 1: Cylinders without fusible plugs
ISO 3807-2:2000, Cylinders for acetylene — Basic requirements — Part 2: Cylinders with fusible plugs
ISO 13341, Transportable gas cylinders — Fitting of valves to gas cylinders
ISO 13769, Gas cylinders — Stamp marking
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
acetylene bundle
transportable unit consisting of two or more acetylene cylinders manifolded together within a rigid frame,
equipped with all necessary equipment for filling and emptying in the assembled state
3.2
acetylene cylinder
pressure vessel manufactured and suitable for transport of acetylene, containing a porous mass and solvent
(where applicable) for acetylene with valve and other accessories fixed to the cylinder
NOTE 1 For solvent-free acetylene cylinders, see Clause 6 of ISO 3807-1:2000 or ISO 3807-2:2000.
NOTE 2 When there is no risk of ambiguity, the word “cylinder” is used.
3.3
acetylene/solvent ratio
ratio of the maximum acetylene content to the specified solvent content
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ISO 10462:2005(E)
3.4
competent authority
any national body or authority designated or otherwise recognized as such for any purpose in connection with
this International Standard
3.5
competent person
person who by a combination of training, experience and supervision is able to make objective judgments on
the subject
3.6
complete cylinder
cylinder shell ready to be charged with acetylene gas that is complete with porous mass, solvent (where
applicable), saturation gas (where applicable), valve and any valve protection permanently fixed to the
cylinder shell
3.7
cylinder shell
pressure vessel manufactured and suitable for receiving and containing a porous mass and to be filled as an
acetylene cylinder
3.8
manufacturer
company responsible for filling the cylinder shell with porous mass and which generally prepares it for the first
charge of acetylene
3.9
maximum acetylene content
specified maximum mass of acetylene the cylinder is designed to contain
NOTE 1 Maximum acetylene content is expressed in kilograms.
NOTE 2 When a solvent is used, it includes the saturation gas.
3.10
maximum permissible settled pressure
maximum permissible gauge pressure, at a uniform temperature of 15 °C, in a cylinder containing the
maximum acetylene content and the specified solvent content
NOTE Maximum permissible settled pressure is expressed in bar.
3.11
porosity
ratio of the total volume (water capacity) of the cylinder shell minus the volume of the solid material of the
porous mass, to the water capacity of the cylinder shell
NOTE Porosity is expressed as a percentage.
3.12
porous mass
porous substance
single or multi-component material introduced or formed in the cylinder shell in order to fill it and that, due to
its porosity, allows the absorption of the solvent and acetylene gas solution
NOTE The porous mass may be monolithic or non-monolithic. Monolithic porous mass consists of a solid product
typically obtained by reacting materials or by bonding materials together with a binder. Non-monolithic porous mass
consists typically of granular, fibrous or similar materials without addition of a binder.
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ISO 10462:2005(E)
3.13
solvent
liquid that is absorbed by the porous mass and is capable of dissolving and releasing the acetylene
NOTE The following abbreviations are used:
“A” for acetone;
“DMF” for dimethylformamide.
3.14
tare weight
reference mass of the acetylene cylinder with the specified amount of solvent
NOTE 1 Tare weight is expressed in kilograms.
NOTE 2 This is further specified in accordance with 3.14.1, 3.14.2 or 3.14.3.
NOTE 3 For cylinders with solvent, the tare weight is expressed by indicating either one or both of the masses
corresponding to tare A and tare S. For solvent-free acetylene cylinders, the tare weight is expressed by indicating a
tare F. For the tare weight used for cylinders in bundles, see ISO 3807-1 or ISO 3807-2, 7.5.3.
3.14.1
tare A
sum of empty mass of the cylinder shell, the mass of the porous substance (see 3.12), the specified mass of
solvent, the mass of any coating (e.g. paint) used in service, the mass of the valve including thermocouple
where fitted, any fixed valve guard and the mass of all other parts that are permanently attached (e.g. by
clamping or bolt fixing) to the cylinder when it is presented for filling
3.14.2
tare S
tare A plus the acetylene mass required to saturate the solvent at normal atmospheric pressure (1,013 bar)
and at a temperature of 15 °C (saturation gas)
NOTE Tare S is expressed in kilograms.
3.14.3
tare F
tare A minus the specified mass of solvent
3.15
total weight
total mass equal to tare A (or tare F for solvent-free cylinders) plus the maximum acetylene content
NOTE Total weight is expressed in kilograms.
3.16
water capacity (cylinder shell volume)
actual capacity of the cylinder shell, measured by filling the shell with water
NOTE 1 Water capacity is expressed in litres.
NOTE 2 The cylinder shell is defined as being empty of any porous mass, see 3.7.
4 Intervals between periodic inspections
A cylinder shall be due for periodic inspection on its first receipt by a filler after the expiry of the interval in
accordance with the requirements of the United Nations Recommendations on the Transport of Dangerous
Goods, Model Regulations or as specified by national or international authorities (see examples in Annex A).
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ISO 10462:2005(E)
Provided the cylinder has been subjected to normal conditions of use and has not been subjected to abusive
and abnormal conditions rendering the cylinder unsafe, there is no general requirement for the user to return a
gas cylinder before the contents have been used even though the inspection interval may have lapsed.
It is the responsibility of the owner or user to submit the cylinder for a periodic inspection and test within the
interval specified by national or international authorities, or as specified in the relevant cylinder design
standard if this is shorter.
5 Preparation of gas cylinder
5.1 Removal of gas
Before proceeding with the inspection, cylinders shall be depressurized of gas. Cylinders shall be checked for
pressure both before and after depressurization. Depressurization shall be carried out in a safe manner
having due regard to the characteristics of acetylene. Depressurization shall be carried out over a period long
enough to ensure removal of all acetylene, except saturation gas. Precautions shall be taken because
variations in temperature influence the quantity of acetylene in the form of saturation gas.
The absence of a positive pressure reading does not clearly indicate the absence of excess gas due to the
possibility of a blocked valve (see Annex B).
In case of any doubts regarding the efficiency of the depressurization cycle, the cylinder should be weighed.
A cylinder weighing more than the tare weight (see 3.14) stamped on the cylinder is not always a clear
indication of the presence of excess gas. Some relevant factors that have to be considered include a possible
excess of solvent or contamination with water, etc.
A cylinder weighing less than or equal to the stamped tare weight is not always a clear indication of the
absence of gas under pressure. Some relevant factors that have to be considered include a possible solvent
shortage and external corrosion causing a loss of shell weight.
5.2 Preparation for external visual inspection
When necessary, the cylinder shall be cleaned and have all loose coatings, corrosion products, tar, oil or other
foreign matter removed from its external surface by a suitable method, e.g. by brushing, shot-blasting (under
closely controlled conditions to ensure that there is no leakage of acetylene into the brushing or shot-blasting
cabinet), water jet abrasive cleaning, chemical cleaning or other suitable methods. The method used to clean
the cylinder shall be a validated, controlled process. Care shall be taken at all times to avoid damaging the
cylinder and pressure relief devices where fitted or removing excess amounts of cylinder wall (See Annex C).
The external visual inspection in accordance with 6.1 can be carried out at this stage.
NOTE Shot-blasting is a process utilizing iron shot of various sizes. It is not to be confused with or referred to as
sand blasting, grit blasting or other more aggressive processes that remove a significant amount of the base metal or
metallic coatings, which should not be used.
5.3 Valve removal
Before removing the valve from an acetylene cylinder, it shall be determined that the cylinder has been
completely depressurized as described in 5.1. If there is any reason to believe that a valve is blocked, e.g. the
lack of an audible release of gas when opening the valve, and that the cylinder may still contain residual gas
under pressure, checks shall be made, e.g. by introducing an inert gas at a pressure lower than 5 bar and
observing its discharge.
If it is found that the valve is obstructed, then a suitable method shall be employed to remove the gas or the
valve, taking into consideration the design of the valve and taking all necessary precautions having due regard
to the hazards that can result from an uncontrolled operation (see Annex B). De-valving shall take place in the
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ISO 10462:2005(E)
open or in a ventilated area. The temperature of the cylinder when removing the valve should be close to the
ambient temperature to avoid either excess venting of residual gas from the cylinder or ingress of air into the
cylinder.
NOTE The cylinders should not be left open or without valves longer than necessary for the inspection.
5.4 Removal of neck/core hole filters
Acetylene cylinders usually contain neck filters/core hole packing consisting of filter/gauze and felts. Neck
filters and packing materials placed between the top of the porous mass and the base of the valve stem shall
be removed, as appropriate, to enable an adequate inspection of the porous mass in accordance with the
inspection requirements of the porous mass manufacturer. When the inspection requirements cannot be
established, a competent person shall define such inspection requirements. For various types of neck/core
hole filters see Annex D.
Some porous mass manufacturers equip monolithic mass acetylene cylinders with wooden plugs, which form
an integral part of the porous mass. These plugs, which are situated below the neck filter/gauze arrangement,
shall be left intact and not removed for the purpose of the visual examination if the wooden plug is in the right
position permitting the measurement of the gap in accordance with the manufacturer's instruction. If on a
previous inspection the wooden plug has been tampered with or removed by mistake, this plug shall be
replaced in accordance with the porous mass manufacturer's instructions.
Special care shall always be taken when removing filters or packing material in view of the possibility of some
restrictions at the neck with residual pressure underneath, which, if suddenly released, might blow the filter out
with some of the porous substance and cause injury. The presence of fine carbon powder on the filters or
packing material could indicate a flashback has occurred.
6 Inspection and maintenance
6.1 External visual inspection
The external surface of each cylinder shall be inspected for
a) dents, cuts, gouges, bulges, cracks, laminations (see Table C.1) and excessive removal of material from
the cylinder base;
b) heat damage, torch or electric-arc burns (see Table C.1);
c) corrosion (see Table C.2);
d) other defects such as illegible, incorrect or unauthorized stamp markings, or unauthorized additions or
modifications (see Table C.1); and
e) integrity of all permanent attachments (see Table C.2).
Damaged valve guards, threaded neck rings and footrings can be repaired or replaced as appropriate. No
welding or any heat shall be directly applied to the pressure containing part of the cylinder.
For rejection criteria, see Annex C. Cylinders no longer suitable for future service shall be rendered
unserviceable (see Clause 10).
6.2 Examination of the porous mass
Subject to the requirements of 5.4, the porous mass shall be examined for the presence of visible
contamination or other defects that could affect the suppression of an acetylene decomposition. The
examination shall be performed by appropriate use of special spark resistant tools such as metal wire probes,
rods, feeler or clearance gauges to check the firmness and the presence of voids or other defects in the mass
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ISO 10462:2005(E)
(see Annex E). Subclauses 6.2.1 to 6.2.3 give the rejection criteria. Care shall be taken to ensure that the
porous mass is not damaged by the inspection tools. See Table C.1, flash back.
6.2.1 Contamination
The porous mass shall be checked visually for contamination such as the presence of significant fine carbon
powder (see 5.4), water, or oil deposits or whether there has been a discoloration of the porous mass.
Depending on the level of contamination for any of those listed above, the competent person shall decide if
the porous mass is to be rejected.
6.2.2 Monolithic masses – cracking or crumbling
The visual inspection shall verify that the porous mass shows no excessive top clearance (gap between the
top of the cylinder and the monolithic porous mass), and no excessive cracking or crumbling.
Cylinders with masses that show cracking or crumbling less than 1 mm width when they do not incorporate
break outs or dislodging of the mass are acceptable. Small break outs in the top of the cylinder neck/shoulder
area are acceptable as long as the maximum gap is not exceeded at any point. See examples in Annex E in
Figure E.1 a) and Figure E.1 b).
6.2.3 Cavitation or compaction
The maximum gap between the top of the cylinder and the monolithic porous mass shall not exceed that
specified in the type approval for that cylinder. Only those gaps up to the maximum used in the type approval
tests shall apply. If such data is unavailable for cylinders manufactured with monolithic asbestos-containing
mass, the gap shall not exceed 5 mm and for cylinders with monolithic asbestos-free porous mass, the gap
shall not exceed 2 mm. If at a later stage, cylinders with other gap sizes pass the requirements of the
flashback test and are approved, then these gap sizes may also apply.
If the cylinder is equipped with a wooden plug (see 5.4) it shall be checked by applying a gentle load that the
plug is firmly fixed in its position and there is no significant lateral movement.
Additionally, the porous mass shall be checked to ensure that there is no significant lateral movement.
Cylinders showing cavitation or significant lateral movement shall be rejected.
Non-monolithic porous masses that show cavitation or compaction, or a loss of compaction shall be rejected
or repaired in accordance with 6.3.
6.3 Repair of non-monolithic porous mass
A non-monolithic mass that has been rejected due to cavitation shall only be repaired if the repair does not
impair the safety of the cylinder.
The repair of a non-monolithic mass shall be performed according to the instructions of the porous mass
manufacturer or according to the instructions of a competent person, and the method to be used shall be
verified by testing in accordance with ISO 3807-1 or ISO 3807-2. The quantity of material added shall be
recorded, the tare weight of the cylinder adjusted as appropriate and the stamp marking adjusted accordingly.
A cylinder that contains a rejected porous mass that is not suitable for repair in accordance with this clause
shall be rendered unserviceable or its porous mass shall be replaced according to 6.4.
6.4 Replacement of porous mass
If the porous mass is no longer acceptable but the external condition of the shell is satisfactory, then either the
existing porous mass shall be replaced and the shell reused or the complete cylinder shall be made
unserviceable.
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ISO 10462:2005(E)
The removal of the existing porous mass and the solvent shall be carried out in a safe manner and the
cylinder shall be thoroughly cleaned and inspected. Special care shall be taken if the porous mass contains
asbestos.
The internal surface of the cylinder shall be examined for corrosion or other visible defects and, if the shell is
found to be satisfactory, it shall be permissible to introduce a new porous mass (see Annex C). Each cylinder
shall be hydraulically tested at the stamped test pressure by a competent person prior to reintroducing the
new approved porous mass. The marking shall be updated accordingly. See ISO 13769.
6.5 Inspection of pressure relief devices including fusible plugs
Where fusible plugs or other pressure relief devices are used, they shall be examined for damage. Where
damage is found, the device shall be replaced and checked for gas tightness.
6.6 Inspection of valves and other accessories
If a valve or any other accessory is to be reintroduced into service, it shall be inspected and maintained to
ensure that it will perform satisfactorily in service and meet the requirements of gas tightness from the valve
manufacturing standards, e.g. ISO 10297. An example of a suitable method is given in Annex F.
6.7 Inspection of cylinder neck
6.7.1 Cylinder to valve threads
When the valve is removed, the cylinder to valve threads shall be examined to identify the type of thread
(e.g. 25E as specified in ISO 10920) and to ensure that they are
clean and of full form,
free of damage,
free of burrs,
free of cracks, and
free of other imperfections.
Cracks manifest themselves as lines that run vertically down the thread and across the thread faces. They
should not be confused with tap marks (thread machining stop marks). Special attention should be paid to the
area at the bottom of the threads.
6.7.2 Other neck surfaces
Other surfaces of the neck shall also be examined to ensure they are free of cracks or other defects (see
Annex C).
6.7.3 Damaged internal neck threads
Where necessary and where the manufacturer or the competent design authority confirms that the design of the
neck permits, threads may be re-tapped or the thread type changed to provide the appropriate number of
effective threads. After re-tapping or changing the thread form, the threads shall be checked with the appropriate
thread gauge (e.g. ISO 11191 for 25E threads).
6.7.4 Neck ring and collar attachment
When a neck ring/collar is attached, an examination shall be carried out to ensure that it is secure and to
inspect for thread damage. A neck ring shall only be changed using an approved procedure. If it is found that
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ISO 10462:2005(E)
any significant damage to cylinder material has occurred by replacement of the neck ring/collar, the cylinder
shall be rendered unserviceable (see Clause 14).
6.8 Reassembly
Cylinders meeting the requirements of this standard shall be reassembled by replacing, as specified by the
porous mass manufacturer, any packing materials in the neck end and fitting new filters in such a way as to
ensure that when the valve is fitted contact is made between the base of the valve stem and the
filters/packings.
New or reconditioned valves shall be fitted to the cylinder using a suitable jointing material and the torque
necessary to ensure a gas-tight seal between the valve and the cylinder in accordance with ISO 13341.
Where relevant regulations requi
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