At a recent meeting of the BDSG a failing of a cylinder at the neck was highlighted. The image shows an O ring ballooning between the cylinder neck and the valve. This occurs because the tread above the O ring is exposed to sea water and can be prone to corrosion. There are reports of cylinder necks being ground to remove the area of corrosion, this reduces the depth of thread and will result in an automatic fail.
These days, while still costly, cylinders are at the lower end of dive kit costs. They do represent one of the greatest dangers to divers and dive centre operators when they fail under load. We should treat cylinders as consumable and accept that they have a finite safe life.
