Should be immediately outlawed and replaced

Rivets have not been used since the early 1960s, they were replaced by high tech nuts and bolts. The Nuts and bolts are more expensive, but you do not need to heat them before installing them and it is almost impossible to for them to "pop" like rivets.

The problem with welding is it makes a very strong, but leave nothing to stop crack once it starts cracking. This came up in the Liberty Ships of WWII. Prior to WWII it was common to Rivets ships together, but during WWII Kaiser Ship building came up with a way to do it by welding. This worked well till, the US had to start to send those ships to Russia. The water was so COLD it made the steel in the ship very brittle, so brittle that the weld would snap and you would lose the ship. The older Riveted ships did not have this problem for the Rivets permitted the steel to flex in the cold temperatures OR once a crack started it would stop at the next Rivet. It took them a while to figure out why these ships were failing, but once it was found the solution was simple. It involved riveting a long piece of steel along the side of the Liberty Ship (one long steel on EACH side total of two).

http://en.wikipedia.org/wiki/Liberty_ship

Thus in some situation you want something other then welds, but that is why we have engineers to tell us when something is finished. A 75 year old tank failing is NOT evidence of a failure of the DESIGN, but a failure do to age. The Recent cold temperatures may have been a factor in weakening the tank.

Tanks over 50 years old should be inspected at least once every year (or at least once every five years) but no inspections were made and that is the problem here, not that it was riveted.

is to do this before the chemical spill happens. You know, in order to lessen the chances of it happening.

Shit, that's so simple, I'd think even a mountaineer could understand it...

in the first place? And up river?