Looks aren't really a good indicator from a mechanical strength view. After all you could get a huge gouge in the pressure boundary, and skim it off in a lathe - looks good as new if you get my point?

Hydro pressure test are the key, but they won't prevent the rams popping due to high velocity ram rods and the like. We had high velocity problems with our setup so its nothing new, we had tie rods stretching, ram mounting bolts stretching, even the cassis was warping, etc, all through extended use - fatigue did start to creep in as time went on. We designed this out (to a point) by upgrading the design as elements fatigued and replacing components as necessary (we never had a failure though!). But assuming that the pins/tie rods dont fail completely a lot of the energy should be absorbed by this failure and gas should be able to escape relatively easily, although I guess this depends on how the ram is screwed together. But assuming that the ram rod wouldn't escape the ram, I would hazard a guess that this type of failure would be less dangerous than the pressure boundry bursting? Either way both are still pretty dangerous.

I think if someone has the knowledge and technical ability to produce pneumatic components then it should not be too much of a stretch to get them tested.

Screw the haters if you like, or stuff the rules! But if a pneumatic component fails, someone gets hurt and the HSE & insurers get envolved we are all going to have very expensive and heavy paper weights sitting at home.