The solution shall be continuously saturated at room temperature and pressure with 0,414 kPa (0,06 psia) hydrogen sulphide (balance nitrogen). The tested specimens shall not fail within a test duration of 144 hours.
A.4. Corrosion tests, aluminium
Corrosion tests for aluminium alloys shall be carried out in accordance with Annex A of ISO/DIS 7866 and meet the requirements therein.
A.5. Sustained load cracking tests, aluminium
The resistance to SLC shall be carried out in accordance with Annex D of ISO/DIS 7866 and shall meet the requirements therein;
A.6. Leak-Before-Break (LBB) performance test
Three finished cylinders shall be pressure cycled between not more than 2 MPa and nor less than 30 MPa at a rate not to exceed 10 cycles per minute.
All cylinders shall fail by leakage.
A.7. Extreme temperature pressure cycling
Finished cylinders, with the composite wrapping free of any protective coating, shall be cycle tested, without showing evidence of rupture, leakage, or fibre unravelling, as follows:
(a) Condition for 48 hours at zero pressure, 65 °C or higher, and 95 per cent or greater relative humidity. The intent of this requirement shall be deemed met by spraying with a fine spray or mist of water in a chamber held at 65 °C;
(b) Hydrostatically pressurised for 500 cycles times the specified service life in years between not more than 2 MPa and not less than 26 MPa at 65 ° or higher and 95 per cent humidity;
(c) Stabilise at zero pressure and ambient temperature;
(d) Then pressurise from not more than 2 MPa to not less than 20 MPa for 500 cycles times the specified service life in years at – 40 °C or lower;
The pressure cycling rate of (b) shall not exceed 10 cycles per minute. The pressure cycling rate of (d) shall not exceed 3 cycles per minute unless a pressure transducer is installed directly within the cylinder. Adequate recording instrumentation shall be provided to ensure the minimum temperature of the fluid is maintained during the low temperature cycling.
Following pressure cycling at extreme temperatures, cylinders shall be hydrostatically pressured to failure in accordance with the hydrostatic burst test requirements, and achieve a minimum burst pressure of 85 per cent of the minimum design burst pressure. For type CNG-4 designs, prior to the hydrostatic burst test the cylinder shall be leak tested in accordance with paragraph A.10 below.
A.8. Brinell hardness test
Hardness tests shall be carried out on the parallel wall at the centre and a domed end of each cylinder or liner in accordance with ISO 6506. The test shall be carried out after the final heat treatment and the hardness values thus determined shall be in the range specified for the design.
A.9. Coating tests (mandatory if paragraph 6.12(c) of Annex 3 is used)
A.9.1. Coating performance tests
Coatings shall be evaluated using the following test methods, or using equivalent National Standards.
(i) adhesion testing in accordance with LSO 4624 using Method A or B as applicable. The coating shall exhibit an adhesion rating of either 4A or 4B, as applicable;
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