The following main changes have been introduced during the revision of EN 12493:2008+A1:2012: — revision of the shell thickness calculations to avoid any confusion with ADR design pressu
Environmental
The manufacturer shall endeavour to acquire materials and components from suppliers who have a declared environmental policy, see EN ISO 14021, EN ISO 14024 and EN ISO 14025
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
3.2 yield strength upper yield strength ReH or, for steels that do not exhibit a definite yield (non-proportional elongation), the
3.3 cold forming forming at temperatures not less than 25 °C below the maximum permissible temperature for stress relieving, in accordance with the applicable material specifications
3.4 hot forming forming at temperatures above the temperature for stress relieving as stated in the material specifications
The 3.5 sun shield must cover at least the upper third and no more than the upper half of the shell surface, maintaining an air gap of at least 40 mm between the shield and the shell.
3.6 pressure vessel assembly of the pressure-retaining envelope (including the openings and their closures) and non-pressure- retaining parts attached directly to it
Note 1 to entry: Also referred to as "tank" in the ADR
3.7 competent authority authority or authorities or any other body or bodies designated as such in each State and in each specific case in accordance with domestic law
3.8 inspection body independent inspection and testing body approved by the competent authority
3.9 competent person person which by combination of appropriate qualification, training, experience, and resources, is able to make objective judgments on the subject
The manufacturer shall endeavour to acquire materials and components from suppliers who have a declared environmental policy, see EN ISO 14021, EN ISO 14024 and EN ISO 14025.
Suitability
4.2.1 Unless otherwise specified by the design documents, the design temperature range shall be -20 °C to
The construction materials must be appropriate for the intended temperature range In cases where the pressure vessel may experience significantly lower ambient or product temperatures, the design temperature range should be set between -40 °C and +50 °C.
4.2.3 Guidance on selection of material grades is given in Annex A
4.2.4 If additional impact testing is required, it shall be carried out in accordance with EN ISO 148-1 to achieve the impact values specified in 10.2.5.4
The materials used for the pressure receptacle that come into contact with the contents must not include substances that could significantly compromise the material's integrity It is essential to adhere to the steel grades outlined in EN 10028-2.
EN 10028-3, listed in Table A.1, are considered compatible with LPG complying with the limitations on corrosiveness as specified in ISO 9162.
Pressure retaining parts
Pressure-retaining materials must be made from appropriate steels that comply with EN 10028-2 or EN 10028-3, or meet specifications approved by the competent authority All materials should adhere to section 10.2.4, ensuring that the ratio of specified yield strength (ReH) to minimum tensile strength (Rm) does not exceed 0.85 (i.e., ReH/Rm < 0.85) The percentage elongation at fracture must be at least \( \frac{10,000}{\text{actual tensile strength in N/mm}^2} \), with a minimum of 16% for fine-grained steels and 20% for other steels For fine-grained steels, the guaranteed yield strength (ReH) must not exceed 460 N/mm², and the upper tensile strength (Rm) must not exceed 725 N/mm².
Non-pressure retaining parts
Non-pressure retaining components welded to pressure retaining parts must be made from appropriate materials that comply with EN 10025-2 or other approved materials It is essential that all materials used for non-pressure retaining parts are compatible with those of the pressure retaining components and meet the impact requirements outlined in section 10.2.5.4, as tested by the specified method.
Welding consumables
Welding consumables shall be able to provide consistent welds with properties at least equal to those specified for the parent materials in the finished pressure vessel.
Non-metallic materials (gaskets)
Non-metallic materials, such as gaskets, must be compatible with both phases of LPG across the pressure and temperature ranges specified for the design of the road tanker (refer to sections 4.2, Annex B, and Annex C).
Inspection documents for materials
Pressure retaining and non-pressure retaining components welded to the pressure vessel must include material manufacturers' certificates that comply with EN 10204:2004, specifically certificate type 3.1 For all other components, certificates must adhere to EN 10204:2004, certificate type 2.2.
Design conditions
5.1.1 Unless authorised by a national competent authority for use within its territory, in accordance with the provision of EU Council Directive 2008/68/EC [11], the reference temperatures shall conform to Annex B
5.1.2 Design calculations shall be carried out in accordance with Annex D
5.1.3 Account shall be taken of the fatigue loading on all component parts of the pressure vessel and its attachments by conducting an assessment or through proven operating experience
5.1.4 The design of the pressure vessel should take into account the following:
— minimizing the use of materials;
— fittings required for efficient operation of the pressure vessel;
— minimizing the environmental impact of in service maintenance and end of life disposal.
Minimum thickness
5.2.1 The minimum thickness for pressure vessels not exceeding a diameter of 1,8 m shall be 5 mm of reference steel (as defined by ADR) or of an equivalent thickness if in a different steel
5.2.2 For pressure vessels exceeding a diameter of 1,8 m, the minimum thickness shall be 6 mm of reference steel (as defined by ADR) or of an equivalent thickness if in a different steel
5.2.3 The equivalent thickness shall be calculated using the Formula (1):
A 1 minimum elongation at fracture (%) of steel chosen under tensile stress; e 1 minimum shell thickness in chosen steel, in mm; e 0 minimum thickness in reference steel, in mm;
R m1 minimum tensile strength of steel chosen, in N/mm 2
!The minimum shell thickness shall not be less than calculated according to ADR (paragraph 6.8.2.1.17 of the 2015 edition of ADR)."
Surge plates
Pressure vessels intended for operation above 20% full or below 80% full must be equipped with surge plates These surge plates should be designed to allow for complete internal inspection of the pressure vessel Additionally, the volume between any two plates or between a plate and the end of the pressure vessel must not exceed 7,500 liters.
Pressure vessels longer than 4.0 meters, which are operated at more than 20% or less than 80% full, must include transverse surge plates spaced no more than 4.0 meters apart Additionally, these vessels should be designed to allow for complete internal inspection.
5.1.1 Unless authorised by a national competent authority for use within its territory, in accordance with the provision of EU Council Directive 2008/68/EC [11], the reference temperatures shall conform to Annex B
5.1.2 Design calculations shall be carried out in accordance with Annex D
5.1.3 Account shall be taken of the fatigue loading on all component parts of the pressure vessel and its attachments by conducting an assessment or through proven operating experience
5.1.4 The design of the pressure vessel should take into account the following:
— minimizing the use of materials;
— fittings required for efficient operation of the pressure vessel;
— minimizing the environmental impact of in service maintenance and end of life disposal
5.2.1 The minimum thickness for pressure vessels not exceeding a diameter of 1,8 m shall be 5 mm of reference steel (as defined by ADR) or of an equivalent thickness if in a different steel
5.2.2 For pressure vessels exceeding a diameter of 1,8 m, the minimum thickness shall be 6 mm of reference steel (as defined by ADR) or of an equivalent thickness if in a different steel
5.2.3 The equivalent thickness shall be calculated using the Formula (1):
A 1 minimum elongation at fracture (%) of steel chosen under tensile stress; e 1 minimum shell thickness in chosen steel, in mm; e 0 minimum thickness in reference steel, in mm;
R m1 minimum tensile strength of steel chosen, in N/mm 2
!The minimum shell thickness shall not be less than calculated according to ADR (paragraph 6.8.2.1.17 of the 2015 edition of ADR)."
Pressure vessels intended for operation beyond 20% full or below 80% full must be equipped with surge plates These surge plates should be designed to allow for complete internal inspection of the pressure vessel Additionally, the volume between any two plates or between a plate and the end of the pressure vessel must not exceed 7,500 liters.
Pressure vessels longer than 4.0 m, which are operated at more than 20% or less than 80% full, must include transverse surge plates spaced no more than 4.0 m apart Additionally, these vessels should be designed to allow for complete internal inspection.
5.3.3 The area of each surge plate shall be at least 70 % of the cross-sectional area of the pressure vessel in which the plates are fitted
5.3.4 Surge plates shall be able to withstand the load imposed by a full capacity liquid content of the section between the plates in either direction
5.3.5 Surge plates shall be at least 2 mm thick
5.3.6 Provision shall be made for communication and drainage between sections
For pressure vessels with a diameter exceeding 1.8 m and a wall thickness under 6 mm, as well as those up to 1.8 m in diameter with a wall thickness less than 5 mm, the surge plates must match the thickness of the shell Additionally, the volume between any two plates or between a plate and the end of the pressure vessel must not exceed 7,500 liters.
Doubler plates
To reduce stress concentration on the pressure vessel, load-carrying attachments shall incorporate a doubler plate between the attachment and the pressure vessel shell
Non-circular doubler plates shall be designed with as generous as practicable corner radii (minimum radius
25 mm) to reduce stress concentrations
If doubler plates are provided with test sockets they shall be closed with threaded plugs after testing.
Stresses due to motion
Pressure vessels and their permanent attachments shall be able to absorb, under maximum permissible load, forces exerted by the design pressure, and the following dynamic forces:
— in the direction of travel: twice the total mass times gravity;
— at right-angles to the direction of travel: the total mass times gravity;
— vertically upwards: the total mass times gravity;
— vertically downwards: twice the total mass times gravity
Under the forces defined above, the stresses in the pressure vessel and its fastenings shall not exceed the following: a) general membrane stress in the shell, remote from the supports:
— the normal design stress as defined in D.1; b) stresses local to the supports, determined either by experimental analysis or calculation/special analysis:
— the limits specified in EN 13445-3.
Self-supporting pressure vessels
Self-supporting pressure vessels shall be designed to carry bending stresses that would otherwise be carried by the chassis or frame.
Vacuum conditions
Pressure vessels must be engineered to endure vacuum conditions created by the product during operation or other operational scenarios At a minimum, they should be capable of withstanding an external pressure of no less than a specified threshold.
Suitable design methods may be applied from EN 13445-3
Certain liquefied petroleum gases may exhibit vapor pressures lower than atmospheric pressure at winter temperatures, potentially leading to partial vacuum conditions within the pressure vessel during normal operations.
Pressure vessel mountings
5.8.1 Mounting structures shall be fabricated in steel and designed to limit movement of the pressure vessel in relation to the chassis
5.8.2 Pressure vessel mountings and their method of attachment to the shell shall be of sufficient strength to support the pressure vessel when full of water
The design of pressure vessel mountings must align with the vehicle chassis design Designers are required to evaluate the impact of the pressure vessel and its mountings, taking into account the additional loadings specified in section 5.5.
At the pressure vessel design stage, it is crucial to inform the chassis manufacturer that the pressure vessel may undergo a hydraulic test while mounted on the chassis, potentially experiencing pressures that are double its standard carrying capacity.
5.8.4 Pressure vessel mountings designed as an integral attachment to the shell shall be fitted with doubler plates as specified in 5.4 Stitch welding shall not be used.
Internal pipework
5.9.1 The mechanical strength of internal pipework and supports shall be sufficient to withstand the service conditions, including dynamic load
5.9.2 Internal pipework may be attached directly to a pressure vessel boss
5.9.3 Pipework shall be located so as to avoid inadvertent entry of liquid LPG from the liquid inlet line into other pipework terminating in the vapour space
General
For the equipping of LPG road tankers, see EN 12252
To ensure the safety of valves and accessories, they must be protected from external impacts through strategic positioning on the pressure vessel or by incorporating specific design features This can be achieved by installing valves and accessories in recessed areas of the pressure vessel shell or ends, or by utilizing guards designed to endure collisions with other vehicles and the forces encountered during a pressure vessel roll-over.
Reinforcement of openings
Openings shall be reinforced and designed in accordance with D.4
Pressure vessels must be engineered to endure vacuum conditions created by the product during operation or other operational scenarios At a minimum, this design requirement should equate to withstanding an external pressure of no less than a specified threshold.
Suitable design methods may be applied from EN 13445-3
Certain liquefied petroleum gases may exhibit vapor pressures lower than atmospheric pressure at winter temperatures, potentially leading to partial vacuum conditions within the pressure vessel during normal operations.
5.8.1 Mounting structures shall be fabricated in steel and designed to limit movement of the pressure vessel in relation to the chassis
5.8.2 Pressure vessel mountings and their method of attachment to the shell shall be of sufficient strength to support the pressure vessel when full of water
The design of pressure vessel mountings must align with the vehicle chassis design Designers are required to evaluate the impact of the pressure vessel and its mountings, taking into account the additional loadings specified in section 5.5.
At the pressure vessel design stage, it is crucial to inform the chassis manufacturer that the pressure vessel may undergo a hydraulic test while mounted on the chassis, potentially experiencing pressures that are double its standard carrying capacity.
5.8.4 Pressure vessel mountings designed as an integral attachment to the shell shall be fitted with doubler plates as specified in 5.4 Stitch welding shall not be used
5.9.1 The mechanical strength of internal pipework and supports shall be sufficient to withstand the service conditions, including dynamic load
5.9.2 Internal pipework may be attached directly to a pressure vessel boss
5.9.3 Pipework shall be located so as to avoid inadvertent entry of liquid LPG from the liquid inlet line into other pipework terminating in the vapour space
For the equipping of LPG road tankers, see EN 12252
To ensure the protection of valves and accessories from external damage, they should be strategically positioned on the pressure vessel or designed with specific features This can be achieved by either recessing valves and accessories within the pressure vessel's shell or ends or by incorporating a guard that can endure collisions with other vehicles and the forces encountered during a pressure vessel roll-over.
Openings shall be reinforced and designed in accordance with D.4.
Threaded connections
The maximum nominal diameter of threaded connections shall be 80 mm.
Manhole
— at least 500 mm in diameter; or
— at least 420 mm, where reducing the diameter is acceptable to the competent authority
Pressure vessels with a volume not exceeding 3 000 l may be fitted with inspection openings, instead of a manhole, with dimensions conforming to EN 286-1
Manholes must be constructed from forged materials, machined plates, or fabricated using pipes and standard flanges that meet the required temperature and pressure ratings When using plate for pad type manholes, it is essential to conduct ultrasonic testing to identify any laminar defects.
6.4.3 The manhole shall be positioned for ease of access.
Attachment welds
Attachment welds shall be continuous.
Position of attachment welds
Attachments must be designed to prevent water accumulation and allow for weld inspection Ideally, attachment welds should maintain a minimum distance of 40 mm from vessel welds, including longitudinal, circumferential, and opening welds If maintaining this distance is not feasible, attachment welds should completely cross the main welds.
General
8.1.1 Road tanker pressure vessels shall be manufactured in accordance with drawings and specifications approved by a notified/designated !inspection" body
8.1.2 The manufacturer shall be responsible for the competence, training and supervision of their staff
8.1.3 The manufacturer shall ensure, taking into account any instructions from the material supplier that the materials of the finished pressure vessel conform to this European Standard
8.1.4 The manufacturer shall have defined procedures for manufacturing operations, including processes such as forming, welding and heat treatment.
Environment
8.2.1 The environmental impact of welding and allied processes shall be assessed in accordance with
To minimize material wastage, manufacturers should choose appropriately sized materials that align with the specifications of the finished parts Additionally, any unavoidable waste or scrap should be recycled effectively.
8.2.3 Noise levels from the production process should be evaluated and measures put into place to minimise the impact upon the external environment.
Control of materials
The pressure vessel manufacturer must implement a material identification system to trace the origin of all materials used in the fabrication of pressure-retaining and non-pressure-retaining parts that are directly welded to pressure-retaining components This system should include procedures to verify the identity of materials received from suppliers.
Verifying procedures must rely on the certificates and acceptance tests provided by material manufacturers It is essential that the original identification mark of the material is transferred to any parts of the pressure vessel that may lose markings during cutting and forming The manufacturer is responsible for ensuring that the material meets the specifications outlined in the design and drawings.
In the process of laying out and cutting materials for pressure vessels, it is essential that the material identification mark remains clearly visible upon completion Alternatively, manufacturers must implement a documented system to guarantee traceability for all materials used in the finished pressure vessels.
If the material identification mark is unintentionally removed during the manufacturing of a pressure part, the manufacturer must transfer it to another section of the component This transfer must be executed by an individual appointed by the manufacturer.
8.3.5 When identification on materials is transferred, the method of marking shall not have any detrimental effect on the specified material properties
8.3.6 Details of welding consumables shall be retained.
Acceptable weld details
8.4.1 The manufacturer, in selecting an appropriate weld detail, shall consider:
— the ability to carry out necessary non-destructive testing
NOTE 1 Recommended weld details are given in EN 1708-1:2010
The root faces of welding preparations shall be aligned within the tolerances given in the welding procedure specification
NOTE 2 Examples of typical welded joints used on the pressure vessel are given in Annex E
8.4.2 If a pressure vessel is made from more than one shell strake, the longitudinal weld of adjacent strakes shall be staggered by at least 100 mm between weld edges
8.4.3 Where the pressure vessel volume is less than 3 000 l and no internal access is provided, joggle joints are permitted for end to shell joints Only dished ends shall be joggled
8.4.4 Joggles shall be sufficiently clear of the knuckle radius to ensure that the edge of the circumferential weld is at least 12 mm clear of the knuckle
8.2.3 Noise levels from the production process should be evaluated and measures put into place to minimise the impact upon the external environment
The pressure vessel manufacturer must implement a material identification system to trace the origin of all materials used in the fabrication of pressure-retaining and non-pressure-retaining parts that are directly welded to pressure-retaining components This system should include proper procedures to verify the identity of materials received from suppliers.
Verifying procedures must rely on the certificates and acceptance tests provided by material manufacturers It is essential that the original identification mark of the material is transferred to any parts of the pressure vessel that may lose markings during cutting and forming The manufacturer is responsible for ensuring that the material meets the specifications outlined in the design and drawings.
In the process of laying out and cutting materials for pressure vessels, it is essential that the material identification mark remains clearly visible upon completion Alternatively, manufacturers must implement a documented system to guarantee traceability for all materials used in the finished pressure vessels.
If the material identification mark is unintentionally removed during the manufacturing of a pressure part, the manufacturer must transfer it to another section of the component This transfer must be executed by an individual designated by the manufacturer.
8.3.5 When identification on materials is transferred, the method of marking shall not have any detrimental effect on the specified material properties
8.3.6 Details of welding consumables shall be retained
8.4.1 The manufacturer, in selecting an appropriate weld detail, shall consider:
— the ability to carry out necessary non-destructive testing
NOTE 1 Recommended weld details are given in EN 1708-1:2010
The root faces of welding preparations shall be aligned within the tolerances given in the welding procedure specification
NOTE 2 Examples of typical welded joints used on the pressure vessel are given in Annex E
8.4.2 If a pressure vessel is made from more than one shell strake, the longitudinal weld of adjacent strakes shall be staggered by at least 100 mm between weld edges
8.4.3 Where the pressure vessel volume is less than 3 000 l and no internal access is provided, joggle joints are permitted for end to shell joints Only dished ends shall be joggled
8.4.4 Joggles shall be sufficiently clear of the knuckle radius to ensure that the edge of the circumferential weld is at least 12 mm clear of the knuckle
NOTE A typical joggle joint detail is shown in Figure E.2.
Heat treatment and forming
Cold forming
8.5.1.1 Heat treatment of cold formed cylindrical shells is not required
8.5.1.2 Cold formed dished ends shall be heat treated unless the manufacturer can demonstrate that the properties of the finished products conform to the original design
8.5.1.3 Cold formed dished ends that have not been heat-treated shall not be welded or heated locally in the knuckle area to temperatures above 550 °C without subsequent heat treatment.
Hot forming
8.5.2.1 For normalised steels, because of the danger of excessive grain growth, the workpiece temperature during hot forming shall not exceed 1 050 °C Before the final stage of hot forming, or if hot forming is performed only once, the workpiece shall not be heated above 980 °C
8.5.2.2 The duration of hot forming should be kept to a minimum to avoid grain growth
8.5.2.3 If no subsequent heat treatment is applied, hot forming shall be completed above 750 °C, or above 700 °C if the degree of forming in the final stage does not exceed 5 % of the total forming operation
8.5.2.4 Cooling shall be carried out in still air
8.5.2.5 If hot forming is carried out in conditions other than those specified in this subclause, normalizing as specified by the steel manufacturer or supplier shall be carried out after hot forming
8.5.2.6 A competent person shall specify the heat treatment procedure to ensure that the properties of the finished product conform to the original design
8.5.2.7 The hot forming process should be designed to minimise energy consumption and ensure the environmentally friendly disposal of insulating material and other waste.
Testing of formed parts
8.5.3.1 For cold-formed parts not subject to heat treatment, no mechanical tests are required in respect of the forming operation
8.5.3.2 All other formed parts shall have tests carried out after the last forming operation or any heat treatment to demonstrate conformity to the material specification Test pieces shall be taken from an excess length or a redundant piece of the formed part, or from a separate test piece formed to same procedure The test pieces shall consist of one tensile and three impact specimens
8.5.3.3 In the case of formed ends, the test pieces shall be taken from sample ends selected as follows:
— from initial production: one from ten of each family; and
— from production formed ends: one formed part in 1 000 production units, but not less than one per two years
8.5.3.4 Ends with the following characteristics are considered to be a family of ends:
Visual examination and control of dimensions
Pressure vessel manufacturers must submit bought-in formed parts that require acceptance certificates in accordance with EN 10204:2004 for visual examination and dimensional checks in their delivery condition The results of these checks must be documented in the pressure vessel acceptance certificate.
Marking
Pressure vessel components must be clearly marked to identify the material and manufacturer, as outlined in section 8.3 Additionally, for batch testing, the connection to the specific batch must be clearly indicated.
Welding
General
Welding of pressure vessel joints must adhere to EN ISO 3834-2 and can only proceed if specific conditions are met: a welding procedure specification must be created by the manufacturer, and the selected welding procedures must be qualified for their intended application If the design relies on material specifications approved by an inspection body, the welding procedure should be qualified using materials with superior properties Additionally, welders and welding operators must possess valid qualifications, and the quality of welded joints must meet quality level B of EN ISO 5817:2007, unless the design specifications impose stricter requirements for shell longitudinal and circumferential welds.
Longitudinal welds
There shall be not more than one longitudinal weld on any strake Longitudinal welds shall be full penetration butt welds.
Welding procedure specification (WPS)
The manufacturer shall compile a welding procedure specification for each joint or family of joints in accordance with EN ISO 15609-1.
Qualification of WPS
Welding procedures shall be qualified by welding procedure tests conforming to EN ISO 15614-1
Production and testing of test pieces shall be certified by an !inspection body"
Welds shall be subjected to impact testing as specified in 10.2.5.4
8.5.4 Visual examination and control of dimensions
Pressure vessel manufacturers must submit bought-in formed parts that require acceptance certificates in accordance with EN 10204:2004 for visual examination and dimensional checks in their delivery condition, with the results documented in the pressure vessel acceptance certificate.
Pressure vessel components must be clearly marked to identify the material and manufacturer, as outlined in section 8.3 Additionally, for batch testing, the connection to the specific batch must be clearly indicated.
Welding of pressure vessel joints must adhere to EN ISO 3834-2 and can only proceed if specific conditions are met: a welding procedure specification must be created by the manufacturer, and the selected welding procedures must be qualified for their intended application If the design relies on material specifications approved by an inspection body, the welding procedure should be qualified using materials with superior properties Additionally, welders and welding operators must possess valid qualifications, and the quality of welded joints must meet quality level B of EN ISO 5817:2007, unless more stringent requirements are specified in the design documentation.
There shall be not more than one longitudinal weld on any strake Longitudinal welds shall be full penetration butt welds
The manufacturer shall compile a welding procedure specification for each joint or family of joints in accordance with EN ISO 15609-1
Welding procedures shall be qualified by welding procedure tests conforming to EN ISO 15614-1
Production and testing of test pieces shall be certified by an !inspection body"
Welds shall be subjected to impact testing as specified in 10.2.5.4.
Qualification of welders and welding operators
Welders shall be approved in accordance with EN 287-1 and welding operators in accordance with
Production and testing of test pieces shall be certified by an !inspection body"
A list of welders and welding operators and records of approval tests shall be maintained by the manufacturer.
Preparation of edges
Material may be cut to size and shape by any mechanical or thermal cutting process or by combination of these Cutting may be carried out before or after forming
The surface to be welded shall be cleaned of oxide scale, oil, grease, or other foreign substance that could have a detrimental effect on weld quality
To ensure proper welding, edges must be securely held in place using mechanical methods, tack welds, or a combination of both It is essential that tack welds are either removed or integrated into the final weld bead The manufacturer is responsible for confirming that the process of tack welding does not lead to any metallurgical or homogeneity defects.
The manufacturer shall ensure that for welds without a sealing run (single sided welds), the edges are sufficiently aligned and spaced to ensure the required penetration at the weld root
A joggle joint may be used on circumferential welds (see 8.4.3) to act as an integral backing strip.
Attachments and fastenings
Welding of attachments (temporary or otherwise), including supports, to a pressure retaining part shall follow a qualified procedure
Temporary attachments shall be removed by a technique that does not affect the properties of the metal or pressure part to which they are welded
It is essential to ensure that the surface of the area from which an attachment has been removed is free of cracks The surface must be smoothed and tested using magnetic particle or penetrant methods Any identified cracks should be repaired accordingly.
Preheat
8.6.8.1 The manufacturer shall include the preheating temperature in the WPS The preheating temperature shall depend on the composition of the metal to be welded, the weld process, and the arc energy
8.6.8.2 Preheating should conform to EN 1011-2
8.6.8.3 Welding shall not be carried out if the temperature of the parent metal near the joint is less than +5 °C
8.6.8.4 The preheating process should be designed to minimise energy consumption and ensure the environmentally friendly disposal of insulating material and other waste.
Post-weld heat treatment
If post-weld heat treatment is required, it shall be carried out in accordance with Annex G
Post-weld heat treatment is generally unnecessary for the materials and weld thicknesses specified for pressure vessels under this European Standard However, it can be performed if mutually agreed upon by the purchaser and the manufacturer.
Pressure vessels often feature numerous fillet welds that are not subject to testing The presence of residual stresses, combined with pressure and dynamic stresses, significantly increases the likelihood of crack initiation and growth Implementing post-weld heat treatment can effectively reduce these residual stresses, thereby minimizing the risk of cracking.
The post-weld heat treatment process should be designed to minimise energy consumption and ensure the environmentally disposal of insulating material and other waste.
Manufacturing tolerances
Tolerances on the pressure vessel shape shall conform to Annex F
NOTE Annex H gives a conservative method of measuring peaking (including ovality).
Repairs to pressure envelope and direct attachment welds
General requirements
Imperfections shall be repaired by a mechanical or thermal process or combination of these
After the repair is completed, the material's thickness must adhere to the design tolerances and meet the minimum thickness requirements outlined in Clause 5 Additionally, the material should undergo the same non-destructive testing that was initially applied.
After completing any required post-weld heat treatment for welding repairs, the repaired vessel must undergo an additional post-weld heat treatment that aligns with the original specifications.
For welding repairs, undertaken after the hydraulic test, a further hydraulic test shall be carried out unless otherwise agreed with the competent person
NOTE EN 13109 gives advice on the scrapping of LPG pressure vessels.
Repair of surface imperfections in the parent metal
Minor surface imperfections (arc strikes, tool marks, cutting marks, etc.) shall be removed by grinding
The ground-out area shall have a smooth transition into the surrounding areas
Repairs requiring the deposition of weld metal must adhere to a welding procedure that is qualified per EN ISO 15614-1, and welders must be certified according to EN 287-1.
Repair of weld imperfections
The determination of weld imperfection repairs depends on the defect's position, size, and type Repairs can either address just the defect and its surrounding area or require the complete removal of the defective weld When using grinding or other material removal processes that do not involve welding, it is essential to ensure a smooth transition into the surrounding areas.
Thermal gouging shall be carried out using an electrode that minimises contamination of remaining material surfaces
Repairs shall be carried out in accordance with a welding procedure qualified in accordance with
EN ISO 15614-1 Welders shall be qualified in accordance with EN 287-1
Post-weld heat treatment is generally unnecessary for the materials and weld thicknesses specified for pressure vessels under this European Standard However, it can be performed if mutually agreed upon by the purchaser and the manufacturer.
Pressure vessels often feature numerous fillet welds that are not subject to testing, increasing the risk of crack initiation and growth due to residual, dynamic, and pressure-induced stresses Implementing post-weld heat treatment effectively reduces residual stresses, thereby minimizing the likelihood of cracking.
The post-weld heat treatment process should be designed to minimise energy consumption and ensure the environmentally disposal of insulating material and other waste
Tolerances on the pressure vessel shape shall conform to Annex F
NOTE Annex H gives a conservative method of measuring peaking (including ovality)
8.9 Repairs to pressure envelope and direct attachment welds
Imperfections shall be repaired by a mechanical or thermal process or combination of these
After the repair is completed, the material's thickness must adhere to the design tolerances and meet or exceed the minimum thickness outlined in Clause 5 Additionally, the material will undergo the same non-destructive testing that was initially applied.
After completing any required post-weld heat treatment for welding repairs, the repaired vessel must undergo an additional post-weld heat treatment that aligns with the original specifications.
For welding repairs, undertaken after the hydraulic test, a further hydraulic test shall be carried out unless otherwise agreed with the competent person
NOTE EN 13109 gives advice on the scrapping of LPG pressure vessels
8.9.2 Repair of surface imperfections in the parent metal
Minor surface imperfections (arc strikes, tool marks, cutting marks, etc.) shall be removed by grinding
The ground-out area shall have a smooth transition into the surrounding areas
Repairs requiring the deposition of weld metal must adhere to a welding procedure that is qualified per EN ISO 15614-1, and welders must be certified according to EN 287-1.
The extent of repairs of weld imperfections shall be determined by the position, size and type of defect
Repairs can either address just the defect and its immediate surroundings or require the complete removal of the defective weld When using grinding or other material removal methods that do not involve welding, it is essential to ensure a smooth transition into the adjacent areas.
Thermal gouging shall be carried out using an electrode that minimises contamination of remaining material surfaces
Repairs shall be carried out in accordance with a welding procedure qualified in accordance with
EN ISO 15614-1 Welders shall be qualified in accordance with EN 287-1
9 Construction and workmanship of internal pipework
Welding of internal pipework shall be to the same quality as for the pressure retaining parts.
General
All tests shall be carried out after any heat treatment process and prior to any external corrosion protection and finishing
Pressure vessels must adhere to the conformity assessment system specified in the European Standard, which includes the evaluation of design type, recognition of quality assurance systems for production, and initial inspection and testing of the manufactured vessels.
Mechanical testing
Production test plates
To control the continuing quality of welded joints and to ensure their mechanical properties conform to the specification, production test plates shall be welded and tested.
Longitudinal welds
For pressure vessels featuring longitudinal welds, it is essential that test plates, when feasible, are affixed to the shell plate at one end of the weld This ensures that the edges of the test plate align with and replicate the longitudinal weld.
The weld metal must be continuously deposited in the test plates while welding the corresponding longitudinal weld, ensuring consistency in the welding process, procedure, and technique Each pressure vessel requires the production of one test plate.
Circumferential welds
Manufacturers must produce two additional test plates annually or one test plate per pressure vessel, whichever is less, if circumferential welds are completed using a different procedure than the longitudinal welds.
Test plates shall be produced by the same procedure as used in construction of the pressure vessel.
Mechanical tests
Each production test plate shall be tested on specimens as required by Annex I.
Test requirements
The test specimens shall be prepared and tested as follows:
Bend testing and test requirements shall be carried out in accordance with EN ISO 5173
Tests must be conducted following the guidelines of EN ISO 4136 or EN ISO 5178, as applicable It is essential that the tensile strength of the test specimen meets or exceeds the specified minimum value required for the design.
Macroscopic examinations shall be carried out in accordance with EN ISO 17639 and shall show sound build- up of weld beads and sound penetration
Tests shall be carried out in accordance with EN ISO 9016 with a V-shaped notch, perpendicular to the surface of the test specimen
Impact-strength tests are not required on welds with a parent plate thickness less than 5 mm
For plates with a thickness between 5 mm and 10 mm, test specimens should have a cross section of 10 mm in width and match the thickness of the parent plate If necessary, machining to a thickness of either 7.5 mm or 5 mm is allowed.
For parent plates with a thickness of 10 mm or less, testing must be conducted on three specimens featuring a notch at the center of the weld and three specimens with a notch at the center of the heat-affected zone, ensuring the V-notch intersects the fusion boundary at the specimen's center.
For parent plates thicker than 10 mm, testing must be conducted on three specimens from the center of the weld and three from the heat-affected zone, ensuring that the V-notch intersects the fusion boundary at the specimen's center.
The average value from each set of three test specimens must be at least 34 J/cm², with no more than one individual value falling below this threshold Additionally, no individual value should be less than 24 J/cm² These requirements apply to specimens taken from both the center of the weld and the heat-affected zone.
The normal test temperature shall be -20 °C but for pressure vessels that may be subjected to temperatures below -20 °C, as defined in 4.2, impact testing shall be carried out at a temperature of -40 °C
Production factors may lead to variability in mechanical test results, sometimes resulting in outcomes that do not meet the specified standards If test results fail to comply with sections 10.2.5.1 to 10.2.5.4, re-testing will be required.
— one impact test (with three specimens)
In a repeated impact test, it is essential that no individual values from the weld deposit or the heat affected zone fall below 34 J/cm² Additionally, the average of all results from both the original test and the retests must meet or exceed this minimum requirement.
34 J/cm 2 If the retests fail these requirements then the welds represented by the test specimens shall be deemed not to conform to this European Standard.
Non-destructive testing
General
Guidance on the selection of non-destructive test methods for welds is given in Annex J
Macroscopic examinations shall be carried out in accordance with EN ISO 17639 and shall show sound build- up of weld beads and sound penetration
Tests shall be carried out in accordance with EN ISO 9016 with a V-shaped notch, perpendicular to the surface of the test specimen
Impact-strength tests are not required on welds with a parent plate thickness less than 5 mm
For plates with a thickness between 5 mm and 10 mm, test specimens should have a cross section of 10 mm in width and the same thickness as the parent plate If necessary, machining to a thickness of either 7.5 mm or 5 mm is allowed.
For parent plates with a thickness of 10 mm or less, testing must be conducted on three specimens featuring a notch at the center of the weld and three specimens with a notch at the center of the heat-affected zone.
(with the V-notch crossing the fusion boundary at the centre of the specimen)
For parent plates thicker than 10 mm, testing must be conducted on three specimens from the center of the weld and three from the heat-affected zone, ensuring that the V-notch intersects the fusion boundary at the specimen's center.
The average value from each set of three test specimens must be at least 34 J/cm², with no more than one individual value falling below this threshold Additionally, no individual value should be less than 24 J/cm² These requirements apply to specimens taken from both the center of the weld and the heat-affected zone.
The normal test temperature shall be -20 °C but for pressure vessels that may be subjected to temperatures below -20 °C, as defined in 4.2, impact testing shall be carried out at a temperature of -40 °C
Production factors may lead to variability in mechanical test results, sometimes resulting in outcomes that do not meet the specified standards If test results fail to comply with sections 10.2.5.1 to 10.2.5.4, re-testing will be required.
— one impact test (with three specimens)
In a repeated impact test, it is essential that no individual values from the weld deposit or the heat affected zone fall below 34 J/cm² Additionally, the average of all results from both the original test and the retests must meet or exceed this minimum requirement.
34 J/cm 2 If the retests fail these requirements then the welds represented by the test specimens shall be deemed not to conform to this European Standard
Guidance on the selection of non-destructive test methods for welds is given in Annex J.
Internal imperfections
Examination for internal flaws shall comprise 100 % radiographic and/or ultrasonic examination of shell longitudinal and circumferential welds in accordance with 10.4.1 and 10.4.2 or 10.4.3 as applicable.
Surface imperfections
All welds connecting nozzles, branches, doubler plates, and other attachments to pressure components must undergo 100% magnetic particle and/or penetrant testing for surface imperfections, in compliance with sections 10.4.4 and 10.4.5.
Non-destructive testing for welds
Radiographic testing
Radiographic examinations shall be carried out in accordance with EN 444 and EN ISO 17636-1 and
Radiographic sensitivity shall conform to EN 462-1 and EN ISO 19232-2
Other radiographic techniques may be used by agreement between the purchaser, the manufacturer and the competent person, provided it can be demonstrated that comparable sensitivities can be achieved.
Marking and identification of radiographs
Each weld section must display appropriate symbols to indicate the job or workplace serial number, order number, or a similar distinctive reference Additionally, it should specify the weld location and section, along with arrows or other symbols positioned clearly alongside the outer edges of the weld to identify its position.
The weld location reference is designated by a letter, such as "L" for longitudinal welds and "C" for circumferential welds, followed by numbers (1, 2, 3, etc.) to indicate the sequence of the weld type.
Symbols consisting of lead arrows, letters and/or numerals shall be positioned so that their images appear on the radiograph of the section
Sufficient overlap shall be provided to ensure that radiographs cover the whole of the weld Each radiograph shall exhibit a number near each end
Radiographs of repair welds shall be clearly identified R1, R2, etc for the first repair, second repair, etc.
Ultrasonic testing
Ultrasonic testing shall be carried out in accordance with EN ISO 17640.
Magnetic particle testing
Magnetic particle inspection testing shall conform to EN ISO 17638
Particular care shall be taken to avoid damage to surfaces by misuse of magnetic equipment Any damage that occurs shall be repaired.
Penetrant testing
Penetrant testing of welds shall be carried out in accordance with EN ISO 3452-1.
Qualification of non-destructive testing personnel
Personnel conducting and assessing non-destructive examinations must be qualified and certified according to EN ISO 9712 standards It is essential for non-destructive testing personnel and supervisors to possess sufficient job knowledge along with a fundamental understanding of welding Additionally, testing personnel should operate independently from those responsible for manufacturing.
Visual examination of welds
All welds must undergo a visual inspection upon completion, following the guidelines of EN ISO 17637 The surfaces being examined should be adequately illuminated and devoid of any grease, dirt, scale, residue, or protective coatings This inspection should cover both sides of the welded joint whenever feasible.
Visual examinations should be supplemented by magnetic particle or penetrant testing in case of doubt.
Acceptance criteria
Acceptance criteria for non-destructive and visual examinations must adhere to Annex I Any unacceptable imperfections must be repaired according to section 8.9, or the component will be rejected Imperfections are defined as per EN ISO 6520-1 and EN ISO 6520-2.
Stress limitation and safety precautions at the hydraulic test
During the hydraulic test conducted after the tank's construction, the maximum general membrane stress must not surpass the nominal design stress established for the tank's design.
The first pressurization shall be carried out under controlled conditions with appropriate safety precautions NOTE A recommended procedure is given in Annex K
11 External corrosion protection and finishing
External protection
Pressure vessels shall have sufficient external protection against corrosion arising from atmospheric effects.
Finishing operations
The pressure vessel shall be protected from the ingress of foreign matter during transportation, handling and fixing to the chassis, and other finishing operations
When selecting packaging and protection for the storage and transport of finished products, it is essential to prioritize options that minimize environmental impact This includes utilizing recyclable or biodegradable materials and reducing energy consumption.
Markings that meet ADR standards must be permanently affixed to a corrosion-resistant metal nameplate, which should be securely attached to the pressure vessel or its supports This nameplate must be positioned in an easily accessible location for inspection purposes.
NOTE 1 See sections 6.8.2.5 and 6.8.3.5 of ADR
Penetrant testing of welds shall be carried out in accordance with EN ISO 3452-1
10.5 Qualification of non-destructive testing personnel
Personnel conducting and assessing non-destructive examinations must be qualified and certified according to EN ISO 9712 It is essential for non-destructive testing personnel and supervisors to possess sufficient job knowledge and a fundamental understanding of welding Additionally, testing personnel should operate independently from those responsible for manufacturing.
All welds must undergo a visual inspection upon completion, following the guidelines of EN ISO 17637 The surfaces being examined should be adequately illuminated and devoid of any grease, dirt, scale, residue, or protective coatings This inspection should cover both sides of the welded joint whenever feasible.
Visual examinations should be supplemented by magnetic particle or penetrant testing in case of doubt
Acceptance criteria for non-destructive and visual examinations must adhere to Annex I Any unacceptable imperfections must be repaired per section 8.9, or the component will be rejected Imperfections are defined according to EN ISO 6520-1 and EN ISO 6520-2.
10.8 Stress limitation and safety precautions at the hydraulic test
The maximum general membrane stress during the hydraulic test, conducted upon the completion of tank construction, must not surpass the nominal design stress established for the tank's design.
The first pressurization shall be carried out under controlled conditions with appropriate safety precautions
NOTE A recommended procedure is given in Annex K
11 External corrosion protection and finishing
Pressure vessels shall have sufficient external protection against corrosion arising from atmospheric effects
The pressure vessel shall be protected from the ingress of foreign matter during transportation, handling and fixing to the chassis, and other finishing operations
When selecting packaging and protection for the storage and transport of finished products, it is essential to prioritize options that minimize environmental impact This includes utilizing recyclable or biodegradable materials and reducing energy consumption.
Markings that meet ADR standards must be permanently affixed to a corrosion-resistant metal nameplate, which should be securely attached to the pressure vessel or its supports This nameplate must be located in an easily accessible area for inspection purposes.
NOTE 1 See sections 6.8.2.5 and 6.8.3.5 of ADR
The marking of cylinders and pressure vessels is governed by RID/ADR regulations, which take priority over any provisions in this European Standard Additionally, the European Directive on Transportable Pressure Equipment 2010/35/EU mandates further marking requirements, including π-marking.
Documentation obtained by the manufacturer
Manufacturers must obtain specific documentation, including a type approval certificate, certificates detailing the chemical analysis and mechanical properties of the steel used in pressure vessel construction, and, if necessary, a certificate for formed parts in accordance with EN 10204:2004.
Records prepared by the manufacturer
The manufacturer is required to maintain comprehensive records, including fully dimensioned drawings with material specifications and design criteria, heat treatment records if applicable, mechanical test results, and visual examination and dimensional checks of formed parts Additionally, they must provide welding procedure specifications and qualification certificates in accordance with EN ISO 15614-1, a list of welders along with their approval test records per EN 287-1, and documentation of any weld repairs Furthermore, a certificate of the hydraulic pressure test, radiographs and results from non-destructive tests, a certificate of water capacity measurement, and a certificate of conformity to the European Standard, validated by a notified or designated body, are also necessary.
Retention and supply of documents
The manufacturer or agent shall retain copies of all documentation for at least twenty years Documentation shall be supplied to the purchaser or operator on request
Guidance on selection of material grades
Table A.1 lists material grades from the standards specified in Clause 4 that may be used for fabricating the pressure vessel
Not all of the grades listed have guaranteed mechanical properties that conform to Clause 4 Some grades may require special testing to demonstrate conformity
The steel group as defined in EN 13445-2 is also listed for each of the grades The grouping is referred to in Table I.4
Minimum impact values (V- notched test pieces) Elongatio n after fracture d
P275NL1 P275NL2 P355N P355NH P355NL1 P355NL2 P460NH P460NL1 P460NL2
The values of ReH are applicable for thicknesses up to 16 mm, while the Rm values represent the specified minimums The impact absorbed energy is based on a standard specimen measuring 10 mm × 10 mm According to EN ISO 6892-1, the formula Lo = 5.65√So is used, and the maximum tensile strength must not exceed 720 N/mm², as detailed in section 4.3.
Guidance on selection of material grades
Table A.1 lists material grades from the standards specified in Clause 4 that may be used for fabricating the pressure vessel
Not all of the grades listed have guaranteed mechanical properties that conform to Clause 4 Some grades may require special testing to demonstrate conformity
The steel group as defined in EN 13445-2 is also listed for each of the grades The grouping is referred to in
Minimum impact values (V- notched test pieces) Elongatio n after fracture d
The values of ReH are applicable for thicknesses up to 16 mm, while the Rm values represent the specified minimum requirements The impact absorbed energy is based on a standard specimen measuring 10 mm × 10 mm According to EN ISO 6892-1, the formula Lo = 5.65√So is used, and it is important to note that the maximum tensile strength should not exceed 720 N/mm², as detailed in section 4.3.
Introduction
The liquid volume and developed pressure of LPG in a closed system are a function of the ambient temperature.
General
The reference temperatures outlined in this annex are intended for the design of road tankers operating in ADR Agreement countries However, if a competent authority in a country with lower ambient temperatures permits, the reference temperature specified in Annex C may be authorized for transport within its territory, in accordance with the updated EU Council Directive 2008/68/EC.
Developed pressure
The reference temperature for developed pressure shall be as specified in Table B.1 The corresponding pressure value shall be not less than the minimum test pressure specified in ADR [10]
Table B.1 — Reference temperature for developed pressure
Sun shield Pressure vessel diameter
Filling
B.4.1 The reference temperature used for calculation of maximum allowable fill shall be 50 °C
B.4.2 Pressure vessels shall be designed to be filled in accordance with the following formula:
95ρ 0, a where a is the degree of filling, in kg/l; ρ is the density of the liquid phase at the reference temperature (50 °C)
B.4.3 Pressure vessels shall not become 100 % liquid full at 60 °C
Alternative reference temperatures for design
Introduction
The liquid volume and developed pressure of LPG in a closed system are a function of the ambient temperature.
General
The reference temperatures specified in this annex are applicable for the design of road tankers, provided they are authorized by a national competent authority for use within its territory, in compliance with EU Council Directive 2008/68/EC.
Developed pressure
The reference temperature for developed pressure shall be as specified in Table C.1
Table C.1 — Reference temperatures for developed pressure
Sun shield Pressure vessel diameter
With sun shield 50 a 55 a a Lower values of temperature with a sun shield may be used if justified by experience or experimental testing.
Filling
C.4.1 The reference temperature used for calculation of maximum allowable fill shall be 32,5 °C
C.4.2 Pressure vessels shall be designed to be filled in accordance with the following formula:
0, a where a is the degree of filling, in kg/l; ρ is the density of the liquid phase at the reference temperature (32,5 °C)
C.4.3 Pressure vessels shall not become 100 % liquid full at 40 °C
Alternative reference temperatures for design
The liquid volume and developed pressure of LPG in a closed system are a function of the ambient temperature
The reference temperatures specified in this annex are applicable for the design of road tankers, provided they are authorized by a national competent authority for use within its territory, in compliance with EU Council regulations.
The reference temperature for developed pressure shall be as specified in Table C.1
Table C.1 — Reference temperatures for developed pressure
Sun shield Pressure vessel diameter
With sun shield 50 a 55 a a Lower values of temperature with a sun shield may be used if justified by experience or experimental testing
C.4.1 The reference temperature used for calculation of maximum allowable fill shall be 32,5 °C
C.4.2 Pressure vessels shall be designed to be filled in accordance with the following formula:
0, a where a is the degree of filling, in kg/l; ρ is the density of the liquid phase at the reference temperature (32,5 °C)
C.4.3 Pressure vessels shall not become 100 % liquid full at 40 °C
Design stresses
D.1.1 The nominal design stress, f, shall be the lesser of Formula D.1 or Formula D.2: eH /1,6 f R = (D.1) m / 2,5 f R = (D.2) where f is nominal design stress;
R eH is the yield strength specified in the material standard or specification;
R m is the tensile strength specified in the material standard or specification
D.1.2 The following units shall be used in the formulae in this annex:
Design pressure
The design pressure shall be no lower than the developed pressure according to Annex B or Annex C (where authorised)
The calculations determine the necessary minimum thickness, denoted as \$e_{min}\$, for rigid single tankers and semi-trailers, as well as for tanker and full trailer combinations To obtain the final minimum thickness, \$e_{min}\$, it should be multiplied by the greater value between 1.0 and another specified factor.
T r is the reference temperature for developed pressure given in Table B.1 or Table C.1.
Design formulae
Cylindrical shell calculation
The minimum required thickness shall be the greater of Formula D.3 or Formula D.4:
D 0 is the outside diameter of the shell; p is the design pressure; z is the joint efficiency = 1,0; f is the nominal design stress.
Dished ends
Dished ends can be torispherical, ellipsoidal, or hemispherical For tanker and full trailer combinations, the minimum thickness requirements are as follows: for pressure vessels with a diameter of 1.5 m or greater, the end thickness must be 7 mm; for those with a diameter less than 1.5 m, the end thickness must be 6 mm.
The following rules are limited in application to ends for which:
The required thickness e is the greatest of e s , e y and e b where: p fz e pR
D 0 is the outside diameter of the shell; p is the design pressure; z is the joint efficiency = 1,0; f is the nominal design stress
Dished ends can be categorized as torispherical, ellipsoidal, or hemispherical For tanker and full trailer combinations, the minimum thickness requirements for pressure vessels are as follows: for a diameter \(D\) of 1.5 m or greater, the end thickness must be 7 mm; for a diameter \(D\) less than 1.5 m, the end thickness must be 6 mm.
The following rules are limited in application to ends for which:
The required thickness e is the greatest of e s , e y and e b where: p fz e pR
1 eH , b R f for all materials and β factor determined from Figure D.1 or by calculation (see D.3.2.5);
The article discusses key parameters for shell design, including the outside diameter of the shell (D₀), required thickness of the end (e), minimum thickness of the knuckle to prevent buckling (eₕ), and minimum thickness of the end to limit membrane stress in the central area (eₛ) It also highlights the minimum thickness of the knuckle to avoid axi-symmetric yielding (eᵧ), along with the nominal design stress (f), design stress for buckling calculations (fᵦ), and the design pressure (p).
R inside radius of curvature of central part of torispherical end; r inside radius of knuckle; z joint efficiency = 1,0
The thickness of the spherical end can be minimized to the value \( e_s \) within a circular area, provided it remains at least a distance \( R_e \) away from the knuckle.
Any straight cylindrical flange shall conform to D.3.1 for a cylinder, unless the length is not greater than0,2× D i e, in which case the flange may be the same thickness as the knuckle
An ellipsoidal end is defined as able to produce a truly semi-ellipsoidal shape without distinct spherical knuckle radii
The design method converts these ends to equivalent torispheres that are calculated in accordance with D.3.2.2
NOTE These rules apply only to ends for which 1,7 < K < 2,2 and z = 1
Ellipsoidal ends shall be designed as nominally equivalent torispherical ends with:
K K is the shape factor for an ellipsoidal end; h i is the inside height of the ellipsoidal end
The thickness of a hemispherical end is specified by Formula D.14, while the cylinder to which it is attached must maintain a thickness that meets or exceeds the minimum requirement outlined in D.3.1, extending up to the tangent line.
This method is valid for e/D 0 ≤ 0,16: p fz e pR
K K is the shape factor for an ellipsoidal end; h i is the inside height of the ellipsoidal end
The thickness of a hemispherical end is specified by Formula D.14, while the cylinder to which it is attached must maintain a thickness at or above the minimum established by D.3.1, extending up to the tangent line.
This method is valid for e/D 0 ≤ 0,16: p fz e pR
NOTE The formulae for β, given above, lead to an iterative calculation A computer procedure is recommended
Figure D.1 — Parameter β for torispherical end – Design
Conical shell calculations
This calculation is for offset cones between two cylinders (see Figure D.2)
The cylinders shall have parallel centre lines offset from each other by a distance not greater than the difference between their radii
A thickness shall be calculated in accordance with D.3.3.3 for the junction at the large end
A thickness shall be calculated in accordance with D.3.3.4 for the junction at the small end
The greater of these shall apply to the whole cone
Calculations are not applicable to cones with an apex half angle exceeding 60° or when the condition \(\frac{e \cos \alpha}{D_c} \leq 0.001\) is met, where \(D_c\) represents the mean diameter of the cylinder at the cone's junction.
The minimum permissible thickness of a cone, at any point along its length, shall be the greater of e s and e j, where: × α
0 e p fz e pD (D.25) where α is the greatest semi-angle of the cone at the apex in degrees;
D i is the inside diameter of the cone at the point under consideration;
The outside diameter of the cone at the specified point is denoted as \$D_e\$, while \$e\$ represents the required thickness of the cone The nominal design stress is indicated by \$f\$, and \$p\$ refers to the design pressure Additionally, the joint efficiency is set at \$z = 1.0\$.
The thickness of the cone may be increased locally or generally to provide reinforcement at branches or openings or to carry non-pressure loads
D.3.3.3 Junction between large end of a cone and a cylinder without a knuckle
This subclause is applicable when the joint is a butt weld, ensuring that both the inside and outside surfaces seamlessly blend with the neighboring cone and cylinder, without any localized thickness reduction.
NOTE 1 The junction is the intersection of shell centre-lines (see Figure D.2 b))
= β (D.27) where β is a factor defined above;
The mean diameter of the cone at the large end is denoted as \$D_c\$, while \$e_j\$ represents the required thickness at the junction of the cone's large end Additionally, \$e_1\$ indicates the necessary thickness of the cylinder at the junction, and \$e_2\$ refers to the required thickness at the cone junction The nominal design stress is represented by \$f\$, which can also be expressed as \$f \times \alpha\$.
0 e p fz e pD (D.25) where α is the greatest semi-angle of the cone at the apex in degrees;
D i is the inside diameter of the cone at the point under consideration;
The outside diameter of the cone at the specified point is denoted as \$D_e\$, while \$e\$ represents the required thickness of the cone The nominal design stress is indicated by \$f\$, and the design pressure is represented by \$p\$ Additionally, the joint efficiency is set to \$z = 1.0\$.
The thickness of the cone may be increased locally or generally to provide reinforcement at branches or openings or to carry non-pressure loads
D.3.3.3 Junction between large end of a cone and a cylinder without a knuckle
This subclause is applicable when the joint is a butt weld, ensuring that both the inside and outside surfaces seamlessly blend with the adjacent cone and cylinder, without any local thickness reduction.
NOTE 1 The junction is the intersection of shell centre-lines (see Figure D.2 b))
= β (D.27) where β is a factor defined above;
The mean diameter of the cone at the large end is denoted as \$D_c\$, while \$e_j\$ represents the required thickness at the junction of the cone's large end Additionally, \$e_1\$ indicates the necessary thickness of the cylinder at the junction, and \$e_2\$ refers to the required thickness at the cone junction The nominal design stress is represented by \$f\$.
NOTE 2 Formula D.26 and Formula D.27 are a trial and error calculation for The answer is acceptable if the value is not less than that assumed to calculate β Figure D.3 gives β directly as a function of 0,833p/f and α
The minimum thickness \( e_1 \) of the cylinder near the junction is determined by the greater value between \( e_c \), the required thickness specified in D.3.1, and \( e_j \), which is calculated using Formula D.27.
This thickness shall be maintained for a distance of at least 1,4 l 1 from the junction along the cylinder, where
1 De l = c is the length along the cylinder
The minimum thickness, denoted as \( e_2 \), of the cone near the junction is determined by taking the greater value between \( e \) and \( e_j \) Here, \( e \) represents the thickness of the cone as specified in section D.3.3.2, while \( e_j \) is calculated using Formula D.27.
This thickness shall be maintained for a distance of at least 1,4 l 1 from the junction along the cone, where
D.3.3.4 Junction between the small end of a cone and a cylinder
This subclause applies provided the thicknesses conform to D.3.1 and D.3.3.2
The required thicknesses e 1 for the cylinder or dished ends or e 2 for the cone are determined by applying the following procedure
Assume initial values of e 1 and e 2:
Formula D.28 and Formula D.29 do not provide values for e 1 and e 2 separately These may require adjustment relative to each other to suit the design If:
D p fze (D.32) then e 1 and e 2 are acceptable, where β H is a factor defined in Formula D.29 If:
The derived thickness for parameters e₁ and e₂ must be upheld at distances l₁ and l₂ from the junction, respectively, as specified in D.3.3.3 This process involves repeating calculations with increased values of e₁ and e₂, ensuring that the condition 0 D β p > fze (D.33) is satisfied.
1 offset a) Offset cone b) Cone/cylinder intersection without knuckle: large end c) Cone/cylinder intersection: small end
Conical shells are characterized by increasing values of \( e_1 \) and \( e_2 \) The final thickness derived for \( e_1 \) and \( e_2 \) must be preserved over distances \( l_1 \) and \( l_2 \) from the junction, with \( l_1 \) and \( l_2 \) determined as per section D.3.3.3.
1 offset a) Offset cone b) Cone/cylinder intersection without knuckle: large end c) Cone/cylinder intersection: small end
Figure D.3 — Values of coefficient β for cone/cylinder intersection without knuckle