BS 5045-5:1986 download.Transportable gas containers Part 5: Specification for aluminium alloy containers above 0.5 litre up to 130 litres water capacity with welded seams.
1 Scope
This Part of BS 5045 specifies requirements for the materials, design, construction and testing of containers for the conveyance of gases under pressure; such containers are suitable also for storing gas under pressure. It applies to aluminium alloy containers of water capacity above 0.5 litre up to 130 litres having longitudinal andlor circumferential seams, made by mechanized TIG or MIG welding.
It includes appendices giving examples of design calculations, a description of the methods for pressure testing of containers and a model form of test certificate.
It does not cover the design and manufacture of portable fire extinguishers where the developed pressure of the contents does not exceed 25 barat the appropriate reference temperature; these are specified in BS 5423.
NOTE The titles of the publications referred to in BS 5045-5 are listed on the inside back cover.
2 Manufacture and testing of containers
The manufacture, inspection and testing of containers shall be carried out to the satisfaction of an Independent Inspecting Authority.
3 Classification of gases
3.1 General
For the purposes of the design and filling of the container, gases are classified as follows:
a) Permanent gas. A gas that has a critical temperature below — 10 °C.
b) Liquefiable gas. A gas that is liquefiable by pressure at — 10 °C but which is completely vapourized below 17.5 °C when at 1 013 mbar2.
1) High pressure liquefiable gas. A gas that has
a critical temperature from — 10 °C to 70 °C
inclusive.
2) Low pressure Liquefiable gas. A gas that has
a critical temperature above 70 °C.
Any toxic substance that is liquid at 1 013 mbar pressure at 0 °C, but that boils at or below 30 °C at that pressure, shall be treated as a low pressure liquefiable gas.
Gases that may be contained in aluminium alloy containers are classified in ‘fable 1.
NOTE The temperature which can be reached by the contents of an insulated container, the corresponding developed pressure required for design and the allowable mass of liquefiable gas are all conditional upon the intended degree of insulation proposed with or without the assistance of some form of refrigeration and upon the journey duration.
8.5 For containers used for fire fighting purposes with halons and dry nitrogen the developed pressure requirements shall conform to the appropriate Part of BS 5306.
9 Classification of containers
9.1 General
Containers shall be constructed to one of the classes in 9.2. 9.3 or 9.4 depending on the intended application.
Construction criteria and other factors for each class shall be in accordance with Table 5.
9.2 Class I
Containers shall be constructed to class I if either of the following criteria apply:
a) they are to be used to contain permanent or high pressure liquefiable gas or gas mixture (see Table 1);
b) they are to be used for the transport of a toxic gas (see Table 1).
9.3 Class IA
Construction to class IA is subject to the approval of the Independent Inspecting Authority and requires that the longitudinal and/or circumferential seams shall be made by a mechanized MIG or TIG welding process which has been shown to produce welds free from unacceptable defects.
Containers shall be constructed to class IA if they are to be used for the transport of the gases italicized in Table 1 (i.e. those gases which are of moderate toxicity or which give a sensory warning of a slight escape) subject to the Health and Safety Executive indicating that they have no objection to the proposal.
NOTE No objection will be raised if evidence is produced to show that the design concerned is satisfactory in all respects for the proposed service. Additional tests may be required in support of this evidence.
9.4 Class II
9.4.1 General. Containers for which construction to classes I, or IA, is not prescribed by 9.2 or 9.3 may be constructed to class hA, hR or IIC.
12.2 Valve protection
12.2.1 Containers intended for the transport of toxic andlor flammable gases shall have their valves protected against damage. either by the design of the container or by the provision of a suitable cap or shroud securely attached to the body of the container, except in the following cases:
a) containers intended for the transport of non-toxic flammable gases and carbon monoxide and mixtures thereof where direct consignments are made between filler and user;
b) a container or group of containers securely attached to a cradle (see 12.2.2).
The construction of the cap or shroud shall be such that it is nowhere in contact with any part of the valve or valve body.
The valve cap or shroud shall be provided with a side vent of such size as to prevent any gas pressure accumulating inside the cap or shroud, unless the cap, collar and its fixing are designed to withstand the pressure that could be developed in the container by the content.s at the pressure reference temperature.
If the container is used for a highly toxic gas suitable additional protection shall be provided, such as a valve locking device andlor by the removal of the valve handwheel. A suitably designed gastight plug or cap shall be fitted to the valve outlet to minimize the risk of valve leakage in transit.
NOTE The additional protection may also be provided by means of a non-vented gastight valve cap designed to withstand the pressure that can be developed in the container by the contents at the reference temperature.
In the case of non-vented valve protection the cap shall be provided with a suitable device that will allow any pressure that has accumulated inside the valve cap to be slowly released before removal of the cap.
The protective device shall be of adequate construction to prevent causing damage to the valve that results in the escape of the product if a filled container is dropped from a height of 1.2 m so that the protective device strikes a hard flat surface.
26.2 Radiographic techniques Radiographic examination of the circumferential and longitudinal welds in containers shall be carried out by the double wall single image (or, where practicable, double image) method using a radiographic technique which is sufficiently sensitive to reveal a defect having a thickness equal to 2 % of the combined thickness of the weld and the backing material.
NOTE Reference should be made to BS 3451.
Radiographic examination of bung and boss butt-welds in containers shall be carried out using, where possible, a direct film technique. The sensitivity of the technique shall be as indicated above.
26.3 Assessment of radiograph
The radiograph shall show that the pressure containing welds have complete penetration and freedom from significant defects especially those likely to be of a repetitive character. Particular attention shall be given to the radiograph of the initial test or tests as specified in 26.1.2. In judging what constitute unacceptable defects the provisions of Table 5A.7 of BS 5500:1985 shall be followed as far as they are relevant.
27 Repair of welds
27.1 If, during the hydraulic or tightness tests, minor leaks are found, or if minor but unacceptable defects are found by radiography the weld shall only be repaired by rewelding either by mechanized or by manual means when approved by the Independent Inspecting Authority.
27.2 All weld repairs shall be radiographed except repairs to containers of classes TIA or 11W After rewelding and where necessary re-radiography, all containers shall be reheat-treated as part of a new batch or production run in accordance with clause 16. and shall be retested accordingly.
28 Results of mechanical and pressure tests
28.1 If any of the mechanical tests required under 19.1. except the nick-break test, results in a failure then, at the manufacturer’s discretion, the procedures in either 28.2 or 28.3 shall be followed.
28.2 The mechanical tests in which the failure occurred shall be repeated on a test specimen cut from the same container and all the mechanical tests required under 19.1 shall be carried out on another container from the same batch or production run. If both containers then comply with the requirements of 19.2 to 19.5 inclusive, the batch or production run, if otherwise complying with the requirements of this standard, shall be accepted.