In my 37 years as a mechanical engineer, I've seen a number of collapsed tanks. But I don't think I have ever seen a collapsed railroad tanker. A tank may have a considerable pressure rating, but if it was not designed for vacuum by stiffening rings and other techniques, it could have very little vacuum strength.
Most frequent cause of such a failure is in a tank that contains liquids emitting water vapor on a sub-zero day. The vent line ices shut and and when an operator pumps the tank out, it collapses. In a similar situation, some tanks have an overflow nozzle at the top that is piped down to the ground. If the secondary containment dike around the tank fills with precipitation deeper than the end of the overflow line, that tank can collapse when it is pumped. Most surprising incident I've seen was a million gallon tank that contained a water slurry approaching boiling temperature. That tank had an open 24 inch manway on the top. An inexperienced plant operator inadvertently turned on a cool water spray in the tank ceiling. The sudden condensing of water vapor caused the top of that tank to crinkle like a beer can. Ned _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
