Why do aluminum cylinders made from the 6351-T6 alloy require an eddy current test?
This particular alloy has a history of a phenomenon known as sustained load cracking (SLC) that can cause a cylinder to fail. Aluminum SCUBA cylinders manufactured in 1982 and 1983 require particular attention because the 6351-T6 alloy used during that period had a higher lead content which makes the cylinder more susceptible to SLC. By 1990, the US aluminum cylinder industry was using a different alloy, known as 6061-T6. There are no indications that the 6061-T6 alloy has problems with SLC, and no steel cylinder has ever shown problems with SLC. Click Here to read an article by Bill High, President of PSI Cylinders, Inc., for more information about sustained load cracking in aluminum cylinders.
