Up-to-date lss an biblog rap ic al referenc es c nc rnin such national s an ards may be obtained on ap lc ation to the C N-C NE E Manag ement Cente or to an C N member.. CEN [an / r CENE
Terms and definitions
For the purposes of this document, the following terms and definitions apply
LPG low pressure liquefied gas composed of one or more light hydrocarbons which are assigned to UN 1011,
UN 1075, UN 1965, UN 1969 or UN 1978 only and which consists mainly of propane, propene, butane, butane isomers, butene with traces of other hydrocarbon gases
!transportable pressure receptacle with a water capacity not exceeding 150 l"
0,2 % proof strength Rea (non-proportional elongation) for aluminium alloys, and the 1 % proof strength for unalloyed aluminium in the unhardened state
3.1.4 heat treatment solution heat treatment, quenching and artificial or natural ageing that ensures the strength values required
Symbols
a Calculated minimum thickness of the cylindrical part, in mm
Aa Actual elongation after fracture, determined by the tensile test specified in 7.4 , in %
Amin Minimum elongation after fracture, guaranteed by the manufacturer for the finished cylinder, in % b Calculated minimum thickness of the end of the cylinder, in mm
C Shape factor (see Table 2, Figure 2 and Figure 3) d Outside diameter of the bend test former, in mm (see Figure 6 and Figure 7)
D Outside diameter of the cylinder as given in the design drawing, in mm (see Figure 1) h Height of the cylindrical part of the end, in mm (see Figure 1)
H Outside height of the domed part of the end, in mm (see Figure 1)
L Length of the cylinder, in mm n Ratio of diameter of bend test former to the thickness of the test piece (see Table 4)
Pb Maximum pressure attained during the burst test, in bar
Ph Minimum permissible test pressure, in bar r Inside knuckle radius of the end, in mm (see Figure 1)
R Inside dishing radius of the end, in mm (see Figure 1)
Rea Actual value of yield strength, determined by the tensile test specified in 7.4, in N/mm 2
Reg Minimum value of yield strength, guaranteed by the manufacturer for the finished cylinder, in
Rma Actual value of tensile strength, determined by the tensile test specified in 7.4 , in N/mm 2
Rmg Minimum value of tensile strength, guaranteed by the manufacturer for the finished cylinder, in
N/mm 2 v Utilization factor for the permissible calculated tension (stress reduction factor)
4.1 The manufacturer shall endeavour to acquire materials and components from suppliers who have a declared environmental policy
NOTE For further guidance, see EN ISO 14021, EN ISO 14024 and EN ISO 14025
The pressure-bearing components of the cylinder must be made from AlMgSi1 or AlMg1Si1, ensuring that the corrosion resistance requirements outlined in Annex A are met for AlMgSi1 For non-pressure-bearing parts, AlMgSi0.5 is an acceptable material.
The manufacturer must define the minimum guaranteed values for yield strength, tensile strength, and elongation in the completed cylinders Importantly, the elongation after fracture must not fall below a specified threshold.
Others % each element 0,05 max., total 0,15 max.
NOTE Materials AlMgSi1 and AlMgSi0,5 are equivalent to alloys EN AW-6082 and EN AW-6060 respectively in EN 573–3
Unalloyed aluminium with a minimum of 99.5% aluminium, as well as specific aluminium alloys not listed in Table 1, may be utilized if all criteria of this European Standard are fulfilled, except for section 4.2 Additionally, it is essential to verify LPG/material compatibility per EN ISO 11114-1, ensure compliance with corrosion resistance requirements outlined in Annex A, and confirm that the manufacturer can prove the material's suitability for cylinder production, anticipated service life, and expected usage conditions.
The manufacturer must choose welding materials that are compatible with the base materials, ensuring that the resulting welds achieve the minimum strength values specified in the cylinder's design and guaranteed in the finished product.
4.5 The manufacturer shall keep certificates in accordance with EN 10204:2004 type 3.1, or higher, covering ladle analysis and mechanical properties for material used for pressure retaining parts of the cylinder
The manufacturer must implement a traceability system for materials utilized in cylinder production, ensuring that each material can be traced back to its source.
General requirements
5.1.1 Calculation of the wall thickness of the pressure bearing parts shall be related to the minimum guaranteed yield strength (Reg) in the finished cylinder
5.1.2 For calculation purposes the value of Reg shall be limited to a maximum of 0,85 Rmg
5.1.3 The calculation of wall thickness shall be based on the test pressure Ph of 30 bar
5.1.4 A fully dimensioned drawing, including material specifications, shall be produced
The design of the cylinder must prioritize material efficiency, incorporate necessary fittings, reduce environmental impact during maintenance and disposal, and ensure efficient transportation of the finished product.
Calculation of cylindrical wall thickness
The wall thickness of the cylindrical shell, including any cylindrical part of the ends, shall not be less than: e h h
— For parts of the cylinder without longitudinal seam: v = 1,0
— For parts of the cylinder with longitudinal seam: v = 0,9
In no case shall the actual thickness be less than that specified in 5.5.
Design of ends concave to pressure
5.3.1 Except as permitted in 5.4, the shape of ends of cylinders shall meet the following limitations:
— for torispherical ends: R ≤ D; r ≥ 0,1 D; h ≥ 4 b (see Figure 1);
— for semi-ellipsoidal ends H ≥ 0,192 D ; h ≥ 4b (see Figure 1)
5.3.2 The wall thickness of the ends of cylinders shall not be less than: e h h
The value of C shall be obtained from Table 2 or the graphs given in Figure 2 and Figure 3.
Other shapes of ends
Alternative end shapes not specified in section 5.3 may be utilized, provided their design adequacy is validated through a fatigue test as outlined in section 7.8 or through a comprehensive stress analysis.
Table 2 — Relationship between H/D and shape factor C
NOTE Intermediate values can be obtained by linear interpolation.
Minimum wall thickness
The minimum wall thickness of the cylindrical shell “a” and of the end “b” shall not be less than the value derived from the following formula:
Design of openings
5.6.1 The location of all openings shall be restricted to one end of the cylinder
Each opening in the cylinder must be reinforced with a valve boss or alternative methods to ensure adequate strength and prevent harmful stress concentrations This reinforcement should be validated through design calculations or a fatigue test as specified in section 7.8.
Neck design
5.7.1 Internal neck threads for single hole cylinders shall be in accordance with EN ISO 11363-1
5.7.2 The internal neck threads of multi-hole cylinders shall conform to an established dimensional specification
The external diameter and thickness of the valve boss or neck end of the cylinder must be sufficient to handle the torque applied during valve installation, including any necessary adjustments for alignment The manufacturer is responsible for specifying the maximum allowable torque and must provide test evidence that the neck and thread can endure this torque without incurring significant damage.
NOTE The torque required can vary according to the thread diameter and form, and the type of sealant used
EN ISO 13341 gives guidance on the torque for valve fitting
Figure 1 — Illustration of cylinder ends concave to pressure
Figure 2 — Values of shape factor C for H/D between 0,2 and 0,25
Figure 3 — Values of shape factor C for H/D between 0,25 and 0,5
Stability
To maintain stability, the diameter of the foot ring's surface or any cylinder part in contact with the ground must be at least 75% of the nominal outside diameter.
Valve protection
5.9.1 Valves shall be protected from damage in order to avoid the release of LPG and shall meet the requirements of 7.9
If the conditions outlined in section 5.9.1 are not satisfied, the manufacturer must indicate in the documentation that cylinders should be transported in crates or cradles, or alternatively, provide adequate valve protection during transit Additionally, it must be demonstrated that the valve is capable of withstanding damage without resulting in LPG leakage.
NOTE 1 See EN ISO 14245 and EN ISO 15995
NOTE 2 For valve protection see provisions in 4.1.6.8 RID/ADR
Environment
The environmental impact of welding and allied processes shall be assessed in accordance with
Manufacturers should aim to reduce material waste by choosing appropriately sized materials for the finished parts Additionally, any unavoidable waste or scrap should be recycled.
NOTE 2 Noise levels from the production process should be evaluated and measures put into place to minimize the impact upon the external environment.
Welding qualification
6.2.1 For all welding associated with the pressure envelope, including non-pressure bearing parts, welding procedures shall be specified and qualified according to EN ISO 15607, EN ISO 15609-1 and
EN ISO 15614-2 Welding procedure approval tests shall be carried out in such a manner that the test welds are representative of those made in production
6.2.2 A welding co-ordinator shall be nominated whose qualification is “European Welding Engineer” (EWE) Their tasks and responsibilities shall be specified according to EN ISO 14731
Welders engaged in manual welding must possess approval in accordance with EN ISO 9606-2, while personnel involved in automatic welding are required to have approval as per EN ISO 14732, tailored to the specific types of work and procedures utilized in production.
6.2.3 Records of approval tests shall be retained by the manufacturer.
Plates and pressed parts
Before assembly, the pressure bearing parts of the cylinders shall be visually examined for uniform quality and freedom from defects which could affect the cylinder integrity.
Welded joints
6.4.1 The welding of pressure bearing joints shall be carried out by a fully mechanised or automatic process so as to provide welds of consistent and reproducible quality
6.4.2 Any joint between pressure bearing parts of the cylinder shall be butt welded Joggle joints are not permitted
The weld metal must achieve full penetration with the parent material, ensuring a smooth surface devoid of overlapping, undercutting, or abrupt irregularities Additionally, the weld surface and the adjacent wall surface must be free from cracking, notching, or porosity All welds should comply with category C quality level for imperfections as specified in EN ISO 10042:2005.
Tolerances
The difference between the maximum and the minimum outside diameter of the cylindrical shell, at any cross-section, shall not exceed 1,5 % of the diameter shown on the drawing
The difference between the maximum and minimum wall thickness of the cylindrical shell, at any cross- section, shall not exceed 10 % of the thickness shown on the drawing
The cylindrical part of the shell must maintain a straight line, with any deviation not exceeding 0.3% of its length, unless specified otherwise in the drawing and validated by a fatigue test as outlined in section 7.8.
For a cylinder standing on its base, the cylindrical shell and the axis of the top opening shall not deviate more than 1,5° from the vertical.
Non-pressure bearing attachments
6.6.1 Non-pressure bearing parts shall be attached to the cylinder by welding, and it shall be verified that these attachments are made of compatible materials (see Clause 4)
— permit inspection of the welds;
— be clear of pressure bearing welds; and
— avoid the trapping of water
6.6.3 Where a foot ring is fitted, it shall be of adequate strength (see requirements of 7.9), drained and the space enclosed by the foot ring ventilated e.g by means of openings.
Heat treatment
6.7.1 After completion of welding and before pressure testing, each cylinder shall be heat treated according to 6.7.2 or 6.7.3 as appropriate, depending on material characteristics
6.7.2 The manufacturer shall specify the relevant temperatures for the solution heat treatment and its duration The quenching medium shall also be specified
The manufacturer must define the forming technology used, such as pressing, drawing, or forging If the material's temperature during forming exceeds 400 °C, stabilizing or stress relieving processes must be implemented, with specific details on the temperature and duration provided.
6.7.4 The cylinder manufacturer shall maintain records of the heat treatment
6.7.5 Localized heat treatment shall not be permitted
6.7.6 The heat treatment process shall be designed to minimize energy consumption and the use of coolants, and ensure environmentally friendly disposal of insulating material and other waste.
Closure of openings
To safeguard the thread from harm and to block moisture from entering the cylinder, finished cylinders must be equipped with either a plug made of impermeable compatible material or the suitable valve or fitting.
Table 3 – Applicability of tests/examinations
Test/Examination Subclause Type test Production test
Specified in subclause Specified in subclause
O - This allows for an option of a radiograph or macro
X - No option permitted – test to be performed
Y - Retest required under certain circumstances
General
Mechanical tests and macro examinations are essential for assessing the properties of the parent material and welds in pressure-containing parts of cylinders These evaluations must be conducted on test specimens extracted from completed cylinders, with their dimensions and positions adhering to the specifications outlined in section 7.3.
It is essential to minimize the environmental impact of the specified tests by considering the recovery of test fluids, recycling mechanical test specimens, and ensuring the safe disposal of chemicals.
Types of test and evaluation of test results
The tests and examinations to be applied to cylinders shall be in accordance with Clause 8 and Clause 9 This is illustrated in Table 3.
Test specimens and related tests and examinations
Two piece cylinders
For two-piece cylinders featuring a single circumferential weld, test specimens must be collected from the specified locations in Figure 4a and Figure 4b, as outlined in Table 4 Additionally, a sample from each welding process of non-pressure bearing attachments is required for macro examination.
Valve boss welds
The welding of the valve boss shall be checked by radiographic examination in accordance with 7.11 or by macroscopic examination in accordance with 7.6
Type of test Standard Key 1 Description
Tensile test EN ISO 4136 or
EN ISO 5178 T1 specimen taken across each butt weld or, if not possible, along the weld Tensile test EN ISO 6892-1 T2 specimen taken from parent material
Bend test EN ISO 5173 B1 specimen taken across each butt weld with outer surface in tension
Bend test EN ISO 5173 B2 specimen taken across each butt weld with inner surface in tension
Bend test EN ISO 5173 B3 specimen taken from parent material
Nick-break test EN ISO 5173
NB1 for small cylinders: specimen taken across each butt weld with outer surface in tension
Macro test !EN ISO 17639" M1 specimen taken across each butt weld
Macro test !EN ISO 17639" M2 specimen taken from valve boss weld
Key a) cylinders with a circumferential weld b) cylinders with a circumferential weld in the area of the cylinder neck c) cylinders with both circumferential and longitudinal welds
T1 tensile test on weld B3 bend test on parent material
T2 tensile test on parent material NB1 nick-break test on weld
B1 bend test on weld M1 macro test on weld
B2 bend test on weld M2 macro test on valve boss weld
NOTE The location of specimens around the circumference of the cylinder is not specified
Tensile test
General
7.4.1.1 Test specimens that are not sufficiently flat for the tensile test shall be flattened by cold pressing As a result, they will show higher values for tensile and yield properties Comparative measurements on welded flat test pieces, using the same parent and welding materials, shall be carried out in order to determine a correction factor
7.4.1.2 For the tensile test on the parent material, the two faces of the test specimen representing the inside and outside surfaces of the cylinder respectively shall not be machined
7.4.1.3 The values obtained for yield strength (Rea), tensile strength (Rma) and elongation after fracture, (Aa) shall not be less than those guaranteed by the cylinder manufacturer for the finished cylinder (Reg, Rmg and Amin).
Parent material
The preparation of test specimens and procedure for carrying out the tensile test shall be in accordance with EN ISO 6892-1
The yield strength (Rea), tensile strength (Rma), and elongation after fracture (Aa) must meet or exceed the values guaranteed by the cylinder manufacturer for the finished product (Reg, Rmg, and Amin).
Welds
The tensile test perpendicular to the weld must follow EN ISO 4136 standards, utilizing a test specimen with a reduced cross section of 25 mm in width, extending 15 mm beyond the weld edges The specimen's width will progressively increase beyond this central section Additionally, tensile testing conducted longitudinally to the weld will also adhere to specified standards.
The tensile strength value obtained (Rma), shall be not less than that guaranteed by the cylinder manufacturer (Rmg), irrespective of where the fracture occurs.
Bend test
Bend test on parent material
7.5.1.1.1 The preparation of test specimens and the procedure for carrying out the bend test shall be in accordance with EN ISO 5173
The edges of the specimen, as illustrated in Figure 5, can feature a radius or a 45° chamfer not exceeding 0.2 times the thickness of the test piece Additionally, the mandrel must be positioned at the center of the specimen, as shown in Figure 6, and the ratio \( n \) must adhere to the limits specified in Table 5.
Table 5 — Ratio of mandrel diameter to test piece thickness n
Actual measured tensile strength R ma
7.5.1.1.3 The specimen shall be bent around the mandrel by a minimum angle of 180°
No cracks shall appear in the test specimen after bending.
Bend test across the welds
The specimen must be prepared and tested in accordance with EN ISO 5173, ensuring that the edges are rounded to a radius not exceeding 0.2 times the thickness of the test piece, as illustrated in Figure 5.
7.5.2.1.2 The diameter of the mandrel shall be 10 × the thickness of the specimen
Test specimen B1, as illustrated in Figure 4, is to be bent with the outer surface of the weld under tension, while test specimen B2 will be bent with the inner surface in tension In both instances, the specimens must be bent to an angle of 75°, accounting for any pre-existing curvature.
7.5.2.1.4 On bend test specimens containing a weld, the weld shall be machined flush with the parent metal surface
No cracks shall appear on the surfaces of the specimen after bending.
Nick-break test across the welds
7.5.3.1.1 For cylinders as shown in Figure 4b where the diameter (Dw) is less than 120 mm, the bend test can be replaced by a nick-break test
7.5.3.1.2 Nick-break tests shall be carried out in accordance with EN ISO 5173 Test specimens shall be prepared as shown in Figure 5
7.5.3.2.1 When broken at ambient temperature, the fracture shall reveal a sound, homogeneous weld with complete penetration and shall be free from oxide or other inclusions or excessive porosity
Key a) dimensions of test specimen for bend test b) cross section of test specimen for bend test and nick-break test c) dimensions of test specimen for nick-break test
Figure 5 — Dimensions of test specimen
Figure 7 — Illustration of bend test across weld
Macroscopic examination of welds
Procedure
The procedure shall be carried out in accordance with ! EN ISO 17639".
Requirements
7.6.2.1 Examination of a full transverse section of the weld shall show complete fusion and complete penetration In case of doubt, a microscopic examination shall be made of the suspect area 7.6.2.2 Examination of the valve boss weld (see Figure 8) shall show that the weld throat thickness and leg length around the boss are greater than the wall thickness of the cylinder at the weld
Key a cylinder wall b valve boss c weld d leg length e leg length f throat thickness
Figure 8 — Illustration of the valve boss weld
7.6.2.3 Examination of one sample from each welding process of non-pressure bearing attachments shall show that the depth of fusion does not extend to more than 40 % of the wall thickness of the pressure bearing part.
Burst test under hydraulic pressure
Procedure
7.7.1.1 Where it is intended to make stamp markings (in accordance with Clause 10) on a pressure bearing part, cylinders to be tested shall be so marked before the test
7.7.1.2 The test shall be carried out with equipment which:
— enables the pressure to be monitored and increase gradually until the cylinder bursts;
— records the volume of test fluid used; and
— records the pressure at which the cylinder bursts
7.7.1.3 The cylinder shall be pressurized until it bursts and the volumetric expansion of the
— the volume of water used between the time when the pressure starts to rise and the time of bursting; or
— the difference between the volume of a cylinder from the beginning and at the end of the test
7.7.1.4 After the cylinder has burst, the rupture surface shall be subject to examination of the tear and shape of its edges (see 7.7.2.3).
Requirements
The measured burst pressure Pb shall be not less than twice the hydraulic test pressure Ph
The ratio of the volumetric expansion of the cylinder to its initial volume shall be not less than 8 % 7.7.2.3Type of fracture
The examination of the fracture shall show that:
— there is no fragmentation of the cylinder;
!— the cylinder shall remain in one piece;"
— ! the main tear shall not be of a brittle type";
— ! the edges of the fracture shall not be radial but shall be sloping in relation to a diametrical plane and shall display a contraction"; and
— the fracture does not reveal a clear defect in the metal, e.g lamination
!— at each end of the fracture, a maximum of two branches shall be allowed and in this case the shorter branch at each end shall be less than 20 mm long;
The fracture must not extend into areas of the cylinder where the thickness exceeds 1.5 times the maximum thickness measured at the midpoint of the cylinder Additionally, the fracture should not reach the center of the cylinder's base.
Fatigue test
Procedure
7.8.1.1 Where it is intended to make stamp markings (in accordance with Clause 10) on a pressure bearing part, cylinders to be tested shall be so marked before the test
7.8.1.2 The cylinders shall be filled with a non-corrosive liquid and be subjected to successive applications of hydraulic pressure
7.8.1.3 The test shall be carried out at an upper cyclic pressure of either:
— two thirds of the hydraulic test pressure Ph in which case the cylinder shall be subjected to 80 000 cycles without failure, or
— the hydraulic test pressure Ph in which case the cylinder shall be subjected to 12 000 cycles without failure
7.8.1.4 The lower value of the cyclic pressure shall not exceed 10 % of the upper cyclic pressure
7.8.1.5 The frequency of pressure cycles shall not exceed 0,25 Hz (15 cycles/min) The temperature measured on the outside surface of the cylinder shall not exceed 50 °C during the test
7.8.1.6 After the test, the cylinder ends and the welds shall be sectioned.
Requirements
7.8.2.1 There shall be no leakage from the cylinder
7.8.2.2 Measurement of the end and weld sections shall show that the thickness is representative of the design under consideration.
Drop test
Procedure
7.9.1.1 Where it is intended to make stamp markings (in accordance with Clause 10) on a pressure bearing part, cylinders to be tested shall be so marked before the test The test cylinder shall be fitted with the service and transport accessories
7.9.1.2 The cylinders shall be partly filled with water to represent the maximum operating mass and pressurized using a non-flammable gas to the test pressure Ph The cylinders shall be dropped from a height of 1,2 m:
— onto a hard flat surface e.g concrete or steel plate; and
— obliquely onto the valve protection
7.9.1.3 The test shall be carried out in accordance with 6.7 of EN ISO 11117:2008.
Requirements
After the test, the cylinder may show damage, but shall not release any contents.
Visual examination
Procedure
Upon finishing each weld, the visible area must be inspected according to EN ISO 17637 standards The examined welded surface should be adequately illuminated and devoid of any protective coatings, grease, dust, or other contaminants.
Requirements
The weld shall comply with 6.4.3.
Radiographic examination
Procedure
7.11.1.1 Radiographs of the welds shall be made in accordance with ! EN ISO 17636-1:2013 and
Radiography personnel must be qualified to EN ISO 9712:2012 at level 1 or higher and should be supervised by individuals qualified at level 2 or higher, in accordance with EN ISO 17636-2:2013, class B, and relevant standards EN 14784-1 and EN 14784-2.
7.11.1.2 The extent of radiography shall be as shown in Figure 9, Figure 10 or Figure 11
7.11.1.3 The radiographic examination may be replaced by radioscopy provided it is carried out according to a process that provides the same level of examination, imperfection detection and records as the radiographic examination.
Assessment
Assessment of radiographic films shall be based on the original films in accordance with
!EN ISO 19232-1 and EN ISO 19232-2".
Requirements
Permissible limits for imperfections shall be in accordance with the requirements of category C of
Pressure test
Procedure
7.12.1.1 The pressurization medium shall be a liquid or a gas Where a gas is used, additional safety precautions are required
NOTE RID/ADR require the agreement of the competent authority for the use of a gas as the pressurization medium
7.12.1.2 The minimum test pressure to be applied shall be 30 bar
7.12.1.3 During the test, the pressure in the cylinder shall be increased gradually until the test pressure is reached
7.12.1.4 The cylinder shall be isolated and remain under test pressure long enough, but for at least
30 s, to establish that there are no observable leaks while the pressure is maintained.
Requirements
7.12.2.1 There shall be no leaks from the cylinder
7.12.2.2 After the test, the cylinder shall not show any signs of visible permanent deformation Permanent deformation may also be gauged by other suitable methods
Figure 9 — Extent of radiography on welds on cylinders with circumferential welds only
Figure 10 — Extent of radiography on welds on cylinders with circumferential and longitudinal welds
Figure 11 — Extent of radiography on welds on cylinders with a circumferential weld in the area of the cylinder neck
8 Technical requirements for type approval
New cylinder design
8.1.1 Each new design of cylinder shall be subject to type approval
8.1.2 A previously approved cylinder shall be considered to be of a new design, if any of the following conditions apply:
— it is manufactured in a different factory;
— it is manufactured from a different material specification or alloy;
— it is manufactured using any different procedure;
— the dimensions of the cylinder change more than the tolerances specified in the manufacturer’s drawing, except for a change in length only, and of no more than 50 %;
— the L/D ratio increases from ≤ 3 to > 3.
Extent of testing
The manufacturer must provide a batch of at least 50 cylinders of each type, ensuring they are representative of the production cylinders These cylinders should be made from the same materials, possess identical nominal thickness, and undergo the same manufacturing processes as the production units.
8.2.2 If it is intended to make stamp markings (in accordance with Clause 10) on a pressure bearing part, cylinders to be tested shall be so marked before the test
Cylinders must be randomly selected for various tests, including three for fatigue testing as outlined in section 7.8, two for mechanical tests and radiographic/macro tests according to sections 7.4, 7.5, 7.11, and 7.6, two for burst testing as specified in section 7.7, and two for drop testing as detailed in section 7.9 Additionally, two cylinders are required for each of the specified additional tests.
1) dimensional and wall thickness checks to confirm compliance with the design;
2) tolerance checks to confirm compliance with 6.5;
3) visual examination of the surface of the weld in accordance with 7.10;
4) checking the volumetric capacity; and
5) checking of the cylinder markings
NOTE These can be the same cylinders used for the mechanical tests.
Type approval certificate
Each type of cylinder shall be covered by a type approval certificate in accordance with the requirements of the current version of RID/ADR
9 Production testing and examination requirements
Tests and examinations applicable to all cylinders
9.1.1 Where applicable, all cylinders shall be subject to a visual examination of the longitudinal weld from both sides before the cylinder is closed in accordance with EN ISO 17637
9.1.2 Prior to surface treatment, all finished cylinders shall be subject to the following:
— pressure test, as specified in 7.12;
— visual examination of the welds, as specified in 7.10;
— inspection of the neck thread; and
— inspection of the cylinder marking per Clause 10
9.1.3 Cylinders that do not pass the tests shall be rejected and segregated for repair and reassessment or scrapping
NOTE Scrapped cylinders should be disposed of per EN 12816.
Radiographic examination
Radiographic examination must be conducted on the pressure-bearing welds of the first cylinder produced following any change in cylinder type, size, or welding procedure, including machine settings, as well as after any production break lasting more than 4 hours.
9.2.2 At least 1 cylinder from each sub-lot, (see 9.7) shall be selected for radiographic examination of the pressure bearing welds
9.2.3 Where more than one welding machine is used in production, the requirements of 9.2.1 and 9.2.2 shall apply to each machine.
Macro examination
9.3.1 Macro examination shall be carried out on welds of sample cylinders as detailed in Table 4 The sample cylinders shall be selected in accordance with 9.7
9.3.2 Macro examination shall be carried out as specified in 7.6.
Examination of valve boss weld
Radiographic or macro examination shall be carried out at sampling rates and on samples taken from cylinders selected for the mechanical/burst test as specified in 9.7
Examination of non-pressure containing attachment welds
For cylinders with welded attachments completed prior to closure, a visual inspection must confirm the absence of excess penetration Additionally, macro examinations are required on one cylinder at the start of each production shift to ensure quality control.
9.5.2 For cylinders where visual examination for excess penetration has not been carried out, macro examinations shall be carried out on 1 cylinder out of every 1 000 cylinders produced
9.5.3 The examination may be carried out on samples taken from cylinders selected for the mechanical/burst tests specified in 9.7
NOTE The macro examination can be supplemented by radiographic examination at the manufacturer’s discretion.
Unacceptable imperfections found by radiographic or macro examinations
9.6.1 Should any of the radiographic or macro examinations show an unacceptable imperfection, production shall be stopped
Every cylinder welded after the last acceptable radiographic or macro examination must be isolated until it is confirmed that the cylinders meet satisfactory standards through radiography or other suitable methods.
9.6.3 Production shall not be re-started until the cause of the defect has been established and rectified, and the procedure as specified in 9.2 has been repeated
9.6.4 Cylinders that do not pass the test shall be rejected and segregated for repair and reassessment or scrapping Scrapped cylinders shall be disposed of per EN 12816.
Production batch testing (mechanical/burst tests)
Production batch
A production batch is defined as a set of finished cylinders produced consecutively by the same manufacturer, utilizing identical manufacturing processes, designs, sizes, and material specifications These cylinders are made on the same type of automatic welding machines and undergo uniform heat treatment conditions.
NOTE In this context, “consecutively” does not imply continuous production
Key a) for cylinders of volume less than or equal to 35 l b) for cylinders of volume greater than 35 l
Size of lot/sub-lot Symbol No of cylinders Type of tests
250 ! " 2 one subjected to a Burst test and one subjected to
250 ! " 1 one subjected to a Burst test or Mechanical tests
500 ! " 2 one subjected to a Burst test and one subjected to
500 ! " 1 one subjected to a Burst test or Mechanical tests
1 000 2 one subjected to a Burst test and one subjected to
Cylinders with a water capacity of less than 6.5 liters and a burst pressure exceeding 100 bar, as specified in section 9.7, must undergo mechanical tests However, manufacturers have the option to conduct a burst test instead of the mechanical test at their discretion.
Inspection lots
9.7.2.1 For acceptance purposes, the production batch shall be divided into inspection lots not exceeding 1 000 cylinders
9.7.2.2 For selection of sample cylinders for either burst or mechanical tests, each lot is sub-divided into sub-lots of 250 cylinders during the first 3 000 cylinders of a production batch and sub-lots of
Rate of sampling
Where a production batch contains material from more than one cast, the manufacturer shall arrange for samples tested to represent each cast of material used
For large volume manufacturing exceeding 3,000 cylinders, a reduced sampling rate can be implemented only after the manufacturer proves that batch production test results and manufacturing processes are consistently reliable, with no significant interruptions in production.
Except as permitted by ! 9.7.1", the samples taken for “Burst tests or Mechanical tests” shall be alternated between the mechanical and the burst tests
A chart illustrating the rate of sampling is given in Figure 12
9.7.3.2Production batch less than or equal to 3 000 cylinders
From the first 250 cylinders in each inspection lot, representative cylinders shall be taken at random, one for the burst test and one for mechanical tests
From each subsequent group of 250 cylinders in the inspection lot, one representative cylinder shall be taken at random for either the burst test or mechanical tests
9.7.3.3.1Cylinders less than or equal to 35 l capacity
For the first 3 000 cylinders in the production batch, representative cylinders shall be taken as specified in 9.7.3.2
For the remaining cylinders from each inspection lot (1 000 cylinders), representative cylinders shall be taken at random, one for the burst test and one for mechanical tests
For the first 3 000 cylinders in the production batch, representative cylinders shall be taken as specified in 9.7.3.2
In each inspection lot containing 500 cylinders or fewer, random selection will be used to choose representative cylinders for testing Specifically, one cylinder will be selected for a burst test and another for mechanical tests Additionally, from the remaining cylinders in the lot, one representative cylinder will be randomly chosen for either a burst test or mechanical tests.
Additional checks
The sample cylinders selected for mechanical tests shall also undergo the following checks:
— dimensional and wall thickness checks to confirm compliance with the design; and
— tolerance checks to confirm compliance with 6.5.
Failure to meet mechanical and burst test requirements
Mechanical
9.8.1.1 Where there is evidence of a fault in carrying out the mechanical tests, or of any error of measurement, a second test on the same cylinder shall be performed Where the result of this test is satisfactory, the first test shall be ignored
9.8.1.2 Where the second test confirms the initial test result, the procedure specified in 9.8.3.1 or 9.8.3.2 shall be followed.
Burst
In the event of a single cylinder failing the burst test, the procedure specified in 9.8.3.1 or 9.8.3.2 shall be followed.
Production batch retest
9.8.3.1 In the event of a single cylinder failing either the mechanical or burst test, both mechanical and burst tests shall be made as shown in Table 6, the retest cylinders being taken at random from the same sub-lot
Table 6 — Production batch retest requirements
Size of inspected sub-lot Failure Retest
NOTE M denotes mechanical test, B denotes burst test 9.8.3.2 In the event that there is no failure from the retest, the batch shall be accepted
9.8.3.3 When more than one cylinder fails the initial tests or one or more cylinders fails the retest specified in 9.8.3.1, the batch shall be rejected.
Resubmission of a production batch
9.8.4.1 For a rejected production batch, the cylinders shall be rectified and re-tested or be scrapped Scrapped cylinders shall be disposed of per EN 12816
9.8.4.2 Prior to any rectification, the cause of the defect shall be established
9.8.4.3 Recognized weld defects shall be repaired
9.8.4.4 The production batch shall be subject to a second heat treatment cycle
9.8.4.5 The rectified production batch shall be resubmitted as a new production batch for approval
9.8.4.6 Cylinders shall only be subjected to one rectification and re-heat treatment cycle.
Weld repairs
Individual cylinders rejected due to local weld imperfections can be repaired, re-heat treated and re- subjected to the tests specified in 9.1.2
All repairs shall be carried out in accordance with a qualified weld procedure by qualified personnel (see Clause 6)
10.1 Each cylinder shall be marked clearly and legibly with certification, manufacturing and operational information in accordance with the requirements of the current version of RID/ADR and with EN 14894 The requirements of RID/ADR shall override conflicting requirements of EN 14894
NOTE EN 14894 will be regularly amended/revised to ensure its requirements comply with the latest version of RID/ADR
10.2 Where markings are applied by stamping or engraving onto the pressure parts of the cylinder, it shall be demonstrated in the fatigue and burst tests that failure does not initiate in the markings and that the markings remain legible
Each production batch of cylinders must be accompanied by a certificate of conformity, in addition to the type approval certificate mandated by section 8.3 This certificate ensures that the cylinders adhere to the approved type and comply with the current RID/ADR requirements and the relevant European Standard.
Test for assessing susceptibility to intercrystalline corrosion
Specimens
A.1.1.1 Specimens shall be taken from the cylindrical part and both ends of the cylinder so that the tests with the solution as defined in A.1.3.2 can be carried out on metal from 3 parts of the cylinder A.1.1.2 Each specimen shall be of the general shape and dimensions indicated in Figure A.1
A.1.1.3 The surfaces, a1a4b4b1 and a2a3b3b2, which correspond respectively to the inner and outer faces of the cylinder, shall be left in the as-manufactured condition The remaining faces may be made smooth for handling purposes
A.1.2 Pre-treatment of the specimen before corrosive etching
— HNO3 analytical reagent grade, relative density 1,33;
— HF analytical reagent grade, relative density 1,14 (at 40 % v/v solution); and
When selecting chemicals, it is essential to minimize their environmental impact by considering options such as the recovery of test fluids, recycling of mechanical test specimens, and the safe disposal of chemicals.
A.1.2.2.1 Prepare a solution A in a suitable container according to the following proportions:
A.1.2.2.2 Heat solution A to a temperature of (95 ± 2) °C
A.1.2.2.3 Treat each specimen as follows:
— suspend on an aluminium wire;
— immerse in solution A for 1 min;
— immerse each specimen in HNO3 acid, as specified in A.1.2.1 , for 1 min at room temperature to remove any copper deposit which may have formed; and
— remove from the HNO3 acid and rinse in de-ionized water
A.1.2.2.4 To prevent oxidation, specimens shall be subjected to the corrosive etching process, specified in A.1.3 immediately on completion of this pre-treatment.
Corrosive etching process
— NaCl, analytical reagent grade, crystallized;
— H2O2, 100 to 110 volumes, medicinal grade; and
A.1.3.2.1 Prepare a solution B in a suitable container Each litre of solution shall contain the following:
A.1.3.2.2 Because H2O2 is not stable, the purity shall be determined by titration and the quantity added shall be adjusted accordingly a) Maintain solution B at a temperature of (30 ± 1) °C for the duration of the test; b) The quantity of solution B used shall be a minimum of 10 ml/cm 2 of specimen surface area; c) Treat each specimen as follows:
— suspend on an aluminium wire, or place in solution B so that it rests on the corners and does not touch any other specimen;
— remove from solution B and wash in running water and then in de-ionized water;
— immerse each specimen in dilute HNO3 acid (50 %), for 30 s;
— remove from the dilute HNO3 acid and rinse in de-ionized water;
— dry the specimen with air
A.1.3.2.3 Several 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 with each other The minimum quantity of solution B per unit of specimen surface shall be maintained.
Preparation of specimens for examination
Each specimen shall be encased in an appropriate mounting resin so that face a1a2a3a4 can be machined
The mounted specimen shall be machined so that a minimum of 2 mm is removed from face a1a2a3a4, to expose section a´1a´2a´3a´4 (see Figures A.1 and A.2)
The exposed section a´1a´2a´3a´4 shall be polished to permit micrographic examination.
Micrographic examination of specimens
The specimen's polished surface will be analyzed under a microscope with a minimum magnification of × 300 to assess the degree of intercrystalline corrosion on the as-manufactured internal and external surfaces of the cylinder.
NOTE The section can first be examined at low magnification (e.g × 40) in order to locate the most corroded areas.
Interpretation of the micrographic examination
Intergranular corrosion is classified as superficial when specific conditions are met For alloys exhibiting equiaxed crystallization, the corrosion depth around the entire perimeter of the section must not exceed the greater of the specified values.
1) 3 grains in the direction perpendicular to the face examined; or
It is acceptable for local values to be exceeded, as long as no more than 4 examination fields at × 300 magnification exceed these limits Additionally, for alloys that crystallize in one direction due to cold working, the corrosion depth on both the internal and external surfaces of the cylinder must not exceed 0.1 mm.
Tests for assessing susceptibility to stress corrosion
Specimens
Three rings, each with a width of either 4a or 25 mm (whichever is greater), will be extracted from the cylindrical section of the cylinder These rings will feature a 60° section removed and will be stressed using a threaded bolt and two nuts, as illustrated in Figure A.3.
Surface preparation before test
All traces of grease, oil and adhesive used with strain gauges (see A.2.3.2.3) shall be removed with a suitable solvent
NOTE Oily or contaminated rags should be disposed of in an environmentally friendly fashion
Method
A.2.3.1 Preparation of the corrosive solution
A.2.3.1.1 Solution C shall be prepared by dissolving (3,5 ± 0,1) parts NaCl in 96,5 parts of distilled water, by mass
A.2.3.1.2 The pH value of freshly prepared solution C shall be in the range 6,4 to 7,2
A.2.3.1.3 The pH of solution C may be initially corrected by using dilute HCl or dilute NaOH, to bring it into the range 6,4 to 7,2
A.2.3.1.4 Once prepared, solution C shall not be topped up by adding the salt solution described in A.2.3.1.1 but only by the addition of distilled water up to the initial level in the vessel Topping up shall be carried out daily as necessary to ensure that the specimens are fully immersed throughout the test A.2.3.1.5 Solution C shall be replaced every 7 days
4 4a or 25 mm whichever is greater
A.2.3.2 Applying the stress to the specimen
A.2.3.2.1 The specimen shall be compressed so the outer surface is under tension
A.2.3.2.2 The amount of stress applied shall be:
A.2.3.2.3 The actual stress shall be measured by strain gauges or calculated from the following formula:
' where a calculated minimum thickness of the cylindrical part, in mm;
D outside diameter of the cylinder as given in the design drawing, in mm (see Figure 1);
D' diameter of the ring when compressed, in mm; f actual stress applied, in N/mm 2 ;
E modulus of elasticity, in N/mm 2 ;
A.2.3.2.4 The nuts and bolts used to tension the specimens shall be electrically insulated from the specimens and protected from corrosion by the solution
A.2.3.2.5 The 3 specimens shall be immersed in solution C for 10 min and then removed and exposed to the air for 50 min
A.2.3.2.6 This cycle shall be repeated continuously for 30 days or until the specimen breaks, whichever occurs first
A.2.3.2.7 The specimens shall be inspected visually for any cracks
Interpretation of the results
The resistance to stress corrosion is deemed acceptable if all tested specimens remain intact, showing no visible breaks or cracks, even under low magnification (× 10 to × 30), after a 30-day testing period.
Metallographical examination (additional examination)
A.2.5.1 In the event of doubt about the presence of cracks (e.g line of pitting), additional metallographic examination of a section taken of the specimen in the suspect area shall be carried out A comparison shall be made of the form (intercrystalline or transcrystalline) and depth of penetration of the corrosion on the faces of the specimen subject to tensile and compressive stresses
A.2.5.2 The resistance to stress corrosion shall be considered acceptable if the corrosion of both faces of the ring ! is" similar Where the face of the ring subject to tensile stress reveals cracks, which are clearly deeper than those on the face subject to compressive stress, the resistance to stress corrosion shall be deemed not acceptable.
Conclusion of corrosion tests
Materials that pass both sets of corrosion tests carried out in accordance with A.1 and A.2, shall be considered to have satisfied 4.3.
Test report
Upon completion of the test, a report will be generated that includes the following details: the name of the material or alloy along with its standard number, the chemical composition with specified limits, the actual analysis of the cast used for manufacturing the cylinders, the actual mechanical properties of the material or alloy compared to the minimum required properties, and the results of the conducted tests.
[1] EN 573-3, ! Aluminium and aluminium alloys - Chemical composition and form of wrought products - Part 3: Chemical composition and form of products"
[2] !CEN/TS 16765, LPG equipment and accessories — Environmental considerations for CEN/TC
[3] EN ISO 13341, Gas cylinders - Fitting of valves to gas cylinders (ISO 13341)
[4] EN ISO 14021, Environmental labels and declarations - Self-declared environmental claims (Type II environmental labelling) (ISO 14021)
[5] EN ISO 14024, Environmental labels and declarations - Type I environmental labelling - Principles and procedures (ISO 14024)
[6] EN ISO 14025, Environmental labels and declarations - Type III environmental declarations - Principles and procedures (ISO 14025)
[7] EN ISO 14245, Gas cylinders - Specifications and testing of LPG cylinder valves - Self-closing (ISO
[8] EN ISO 15995, Gas cylinders - Specifications and testing of LPG cylinder valves - Manually operated (ISO 15995)
[9] ADR, European Agreement concerning the International Carriage of Dangerous goods by Road
[10] RID, Regulations concerning the International Carriage of Dangerous Goods by Rail
[11] Directive 2010/35/EU of the European Parliament and of the Council of 16 June 2010 on transportable pressure equipment
[12] Measurement uncertainty leaflet (SP INFO 2000 27 uncertainty pdf), Magnus Holmgren et al, published by Swedish National Testing and Research Institute