It is important that your LPG tank is tested by a qualified engineer in order to meet Pressure Systems Safety Regulations. There are certain rules you need to follow when it comes to installing your LPG tank.
Quite often when your tank is filled the delivery driver will check it over and if any issues are noticed it will be reported back to your LPG supplier. They are only officially tested every 10 years and 20 years but if you notice any problems you should contact your LPG supplier.