ISO 11439:2000 pdf download

ISO 11439:2000 pdf download.Gas cylinders – High pressure cylinders for the on-board storage of natural gas as a fuel for automotive vehicles.
4 Service conditions
4.1 General
4.1.1 Standard service conditions
The standard service conditions specified in this clause are provided as the basis for the design, manufacture, inspection, testing and approval of cylinders that are to be mounted permanently on vehicles and used to store natural gas at ambient temperatures for use as a fuel on the vehicles.
4.1.2 Use of cylinders
The service conditions specified are also intended to provide information on how cylinders manufactured in accordance with this International Standard may safely be used; this information is intended for
a) manufacturers of cylinders;
b) owners of cylinders;
C) designers or contractors responsible for the installation of cylinders;
d) designers or owners of equipment used to refuel vehicle cylinders;
e) suppliers of natural gas;
f) regulatory authorities who have jurisdiction over cylinder use.
4.1.3 Service life
The service life for which cylinders are safe shall be specified by the cylinder manufacturer on the basis of use under service conditions specified herein. The maximum service life shall be 20 years.
For metal and metal-lined cylinders, the service life shall be based upon the rate of fatigue crack growth. The ultrasonic inspection, or equivalent, of each cylinder or liner shall ensure the absence of flaws which exceed the maximum allowable size. This approach permits the optimized design and manufacture of light weight cylinders for natural gas vehicle service.
For all-composite cylinders with non-metallic non-load bearing liners the service life shall be demonstrated by appropriate design methods, design qualification testing and manufacturing controls.
4.2 Maximum pressures
This International Standard is based upon a working pressure of 200 bar settled at 15 °C for natural gas as a fuel with a maximum filling pressure of 260 bar. Other working pressures may be accommodated by adjusting the pressure by the appropriate factor (ratio); e.g., a 250 bar working pressure system will require pressures to be multiplied by 1,25.
Except where pressures have been adjusted in this way, the cylinder shall be designed to be suitable for the following pressure limits:
a) a pressure that would settle to 200 bar at a settled temperature of 15 °C;
b) the maximum shall not exceed 260 bar, regardless of filling conditions or temperature.
4.6 External surfaces
It is not necessary for cylinders to be designed for continuous exposure to mechanical or chemical attack, e.g. leakage from cargo that may be carried on vehicles or severe abrasion damage from road conditions. However, cylinder external surfaces shall be designed to withstand inadvertent exposure to the following, consistent with installation being carried out in accordance with the instructions to be provided with the cylinder:
a) water, either by intermittent immersion or road spray;
b) salt, due to the operation of the vehicle near the ocean or where ice-melting salt is used;
c) ultra-violet radiation from sunlight;
d) impact of gravel;
e) solvents, acids and alkalis, fertilizers;
f) automotive fluids, including petrol, hydraulic fluids, battery acid, glycol and oils;
g) exhaust gases.
5 Approval and certification
5.1 Inspection and testing
Evaluation of conformity is required to be performed in accordance with the relevant regulations of the country(ies) where the cylinders are used.
In order to ensure that the cylinders are in compliance with this International Standard they shall be subject to design approval in accordance with 5.2, and inspection and testing in accordance with either clause 6, 7, 8 or 9 as appropriate to the construction. This shall be carried out by an authorized inspection authority (hereafter referred to as “the Inspector”) recognized in the countries of use. The Inspector shall be competent for inspection of cylinders.
Test procedures are detailed in annex A and annex B. An example of acceptable approval and certification procedures is included in annex C.
5.2 Type approval procedure
5.2.1 General
Type approval consists of 2 parts:
a) design approval, comprising submission of information by the manufacturer to the inspector, as detailed in
5.2.2.
b) prototype testing, comprising testing carried out under the supervision of the Inspector. The cylinder material, design, manufacture and examination shall be proved to be adequate for their intended service by meeting the requirements of the prototype tests specified in 6.5, 7.5, 8.5 or 9.5, as appropriate for the particular cylinder design.
The test data shall also document the dimensions, wall thicknesses and weights of each of the test cylinders.