<P> A cylinder is due to be inspected and tested at the first time it is to be filled after the expiry of the interval as specified by the United Nations Recommendations on the Transport of Dangerous Goods, Model Regulations, or as specified by national or international standards applicable in the region of use . </P> <Ul> <Li> In the United States, an annual visual inspection is not required by the USA DOT, though they do require a hydrostatic test every five years . The visual inspection requirement is a diving industry standard based on observations made during a review by the National Underwater Accident Data Center . </Li> <Li> In European Union countries a visual inspection is required every 2.5 years, and a hydrostatic test every five years . </Li> <Li> In Norway a hydrostatic test (including a visual inspection) is required 3 years after production date, then every 2 years . </Li> <Li> Legislation in Australia requires that cylinders are hydrostatically tested every twelve months . </Li> <Li> In South Africa a hydrostatic test is required every 4 years, and visual inspection every year . Eddy current testing of neck threads must be done according to the manufacturer's recommendations . </Li> </Ul> <Li> In the United States, an annual visual inspection is not required by the USA DOT, though they do require a hydrostatic test every five years . The visual inspection requirement is a diving industry standard based on observations made during a review by the National Underwater Accident Data Center . </Li> <Li> In European Union countries a visual inspection is required every 2.5 years, and a hydrostatic test every five years . </Li>

How long is a scuba tank hydro good for