BS EN 14359:2017 download.Gas-loaded accumulators for fluid power applications.
1.1 BS EN 14359 specifies the requirements for materials, design, manufacture, testing inspection, safety equipment configuration and documentation (including instructions for first operation), for commonly-used types of gas-loaded accumulators and pressure vessels used to provide additional gas capacity for fluid power applications (see 12).
1.2 BS EN 14359 applies to the following types of components, defined as the pressure-
containing envelope of gas-loaded accumulators:
— bladder type;
— diaphragm type;
— piston type;
— transfer type;
— pressure vessels used to provide additional gas capacity.
They consist of one or several parts joined together by a variety of mechanical means and by welding.
1.3 BS EN 14359 applies to gas-loaded accumulators which operate with the
following conditions:
— subject to an internal gauge pressure greater than 0,5 bar;
— working temperature not lower than -50 °C and not higher than +200 °C;
— containing all liquids and gases as defined in the Pressure Equipment Directive 2014/68/EU, see Note.
NOTE When the accumulator contains Group 1 liquids or gases, consideration relating to risks other than those required by Pressure Equipment Directive 2014/68/EU are not covered by this European Standard and will be assessed separately.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its anolication. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 10204, Metallic products — Types of inspection documents
EN 13018, Non-destructive testing — Visual testing — General principles
EN 13445-2, Unfired pressure vessels — Part 2: Materials
EN 13445-3:2014, Unfi red pressure vessels — Part3: Design
EN 13445-4, Unfired pressure vessels — Part 4: Fabrication
EN ISO 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method (iSO 148-1)
EN ISO 898-1, Mechanical properties of fasteners mode of carbon steel and alloy steel — Part 1: Bolts, screws and studs with specified property classes — Coarse thread and fine pitch thread (ISO 898-i)
EN ISO 6506-1, Metallic materials — Brinell hardness test — Part 1: Test method (ISO 6506-1)
EN ISO 6506-2, Metallic materials — Brinell hardness test — Part 2: Verification and calibration of testin,q machines (ISO 6506-2)
4.2 Material certificates for components of the pressure containing envelope
Components used in the manufacture of the pressure containing envelope of gas-loaded accumulators to category II. Ill and IV according to Annex II of the Pressure Equipment Directive 2014/68/EU shall be accompanied by an inspection document in accordance with EN 102C)4 type 3.1 (see Annex Ill of the Pressure Equipment Directive 2014/68/EU). Such components shall include, but not be limited to. those determined by the application of the calculation formulae within this standard.
S Basic design and calculation criteria
5.1 General
The requirements of Clause S shall apply when the materials and welds are not subject to localised corrosion in the presence of either products which the gas-loaded accumulator is to contain, or the environment in which it is located.
5.2 CorrosIon
Where there isa risk of corrosion, a protection method and/or corrosion allowance shall be applied to the affected surfaces of the accumulator
Consideration must be given to the potential for corrosion due, both to the internal fluid and external environment. This should be countered by methods Including, but not limited to. choice of corrosion- resistant materials or the use of linings or coatings.
Only completely impervious, sufficiently thick and chemically stable layers with an average life, not less than that of the pressure vessel, shall be considered to be reliable protection against corrosion. When In doubt, corrosion tests shall be undertaken.
If there Is no contact between the corrosive agent and the vessel base material, then It is not necessary to provide a corrosion allowance for wastage of the base material.
5.3 Qualification by similarity
Accumulators are often serially produced and it Is possible to qualify a range of accumulators based upon the design, calculation and testing olone model within the range provided that other accumulators are similar. Two accumulators are similar provided that:
— they are made of the same material of the same form and origin;
— they are identical with the exception of length;
— the internal length of the cylindrical portion is not less than three times its external diameter.
If the length of the cylindrical portion is less than three times its external diameter, then a detailed stress analysis shall be undertaken.
5.4 Design methods
5.4.1 General
BS EN 14359 specifies methods for the design by formulae of accumulators or accumulator components. Satisfactory application of such formulae alone shall be sufficient to demonstrate conformity to BS EN 14359 provided the accumulator will be subjected to less than 500 pressure cycles between P2 and P1 during Its lifetime.
The diameter of the gas-lilting screw shall be limited to MH as defined in ISO 262 and the sealing diameter shall not exceed the thread diameter by more than 25 %.
57.4.3 Technical requirements for gas-filling screws
Although gas-lilling screws arc pressure-loaded during operation the axial forces are negligible because of the port diameter being less than 8mm, Of more importance are good sealing properties and sale handling by the user. To ensure safety. gas-filling screws of property class at least 8.8 or 10.9 as defined in EN ISO 898-1 shall be used in order to avoid overstressing of the gas-filling screw, or even shearing oft, when higher fastening torques are applied.
Preference shall be given to property class 8.8 or 10,9 albeit the elongation is below the normal range for pressure vessel materials.
The manufacturer shall provide recommended sale torque tightening requirements for gas- tilling screws.
Gas-filling screws may have a safety feature such as a gas bleed opening which allows for the gas to escape before the entire screw becomes detached. The openings may have the form of slots. bore holes or cut-away-sections. When such a feature becomes active, the remaining thread length shall be at least equal to its diameter.
5.8 SpecIfic design criteria for oil ports mainly used In bladder type accumulators
5.8.1 General
The requirements of 5.6 shalt apply when assessing the stresses in oil ports mainly used in bladder type accumubtors.
5.8.2 Oil port design and calculation
5.8.2.1 General
Figure 19 shows the geometry of an oil port.
— proper installation of other devices as specified in
— proper installation of all connecting lines, which shall be suitable for the permissible working pressure and the hydraulic fluid and shall not interfere with any other safety functions:
— visibility of hazard labels.
II pressure release devices are provided that open automatically in the case of a circuit breakdown, a breakdown shall be simulated and the pressure shall decrease to zero.
Conversely, if automatic releasing is not allowed, pressure shall be maintained. Manually-operated devices shall be checked under pressure.
If the user is not able to make the necessary examination himself, they shall be carried out by a Competent Person.
8.4 Supervision and maintenance
Each piece of safety equipment shall be routinely examined, checked for accuracy and maintained on a periodic basis. The frequency of checking and the degree of accuracy required will depend upon experience of the particular application. If the user Is not able to make the necessary assessment of reliability then advice shall be obtained from suitable experts.
Examination shall consist of visual Inspection of the physical Integrity of the equipment and where applicable of the functional availability or readiness of energy supply etc.
Maintenance routines shall be performed by authorized personnel only and shall include the verification of settings and operational testing where applicable.
Maintenance shall also Include routine testing of individual devices after specified service cycles and the exchange of components before the end of expected or experienced lifetime.
Maintenance programs and work, results of examinations and any resulting remedial measures taken shall be documented and retained for 10 years or the lifetime of the installation (if shorter). Replacement of components shall be documented and retained In the same way.