Every country has a standard to make this kind of cylinders. For example in my country there is a standard to make this kind of cylinders. And this instructions must to be followed by any factory which want make LPG cylinders. For example this kind of factoriesmust follows the meassureswelding specifications using special com si com sathe steel used under standard for qualityhardenessetc. Size of cylindersshapescom si com sa the use, for example householdautomotivecom si com sa ,etc.
Any use must have a different design. For example you musnÂ´t use the cylinder desingned for automotive in household and so on. If you want to get more specific information about thisyou should go to your local office for standars in your country. So every country has an office for standards which is something like a library where only you can find all standards instructions to make a lot of things.
Eg. AutomotiveMechanicalChemicalAircraft ,etc.