4 ms·

If you think infosec people are paranoid, boy have you not met a good mechanical engineer yet. Down in the analogue world, random overpressures, voltage spikes

If you think infosec people are paranoid, boy have you not met a good mechanical engineer yet. Down in the analogue world, random overpressures, voltage spikes, simple mechanical fatigure, etc happen all the time, so you're going to have to deal. I've written reports on why, regardless of what a sensor said, a simple static beam made of nonflammable materials neither a) spontaneously combusted, b) broke Clausius's principle and moved heat from a cold body to a hotter body. But we still checked.

ezconnect 6y ago
I agree on this, if something bad happened most critical system are designed to break somewhere to limit the catastrophe, or other times they are over engineered 1,000x because sometimes you can never tell what nature can do to your system.
- TeMPOraL 6y ago
  I wish to believe that. I'd expect it of good engineers. However, I don't trust systems to remain as robust as initially designed, after decades of undergoing constant pressure to reduce costs, make things more (fiscally) efficient, "cut out fat", etc.
  - Arrath 6y ago
    Even the loss of institutional knowledge can degrade the safety of a system over time. Ever had to start maintaining a codebase after the greybeard who made it retired? Did you have any documentation to go off of? Anyone remaining in the company regard it as anything other than a production critical black box? Now imagine that codebase is an industrial process, with 20 years of growth, add-ons, changes. Probably some mismatching control systems, and god only knows if the as-builts or red line plans for the additions are all correct or rectified with each other..
- Arrath 6y ago
  Certainly the systems are designed to. But over the operational life, things happen. Systems degrade, maybe maintenance lapses a bit. Maybe, for example, a mechanic tired of trouble shooting an issue replaces the 9th blown burst disc in a row with one he just cut from the mud flap on his shop truck. NBD, the system was only running 5% over pressure anyway and he wants to go home. Later, this overpressure state backs up through the system and overheats a pump which, considering that it is pumping liquid explosives, isn't ideal. Maybe this trips a temperature sensor and the jury rigged burst disc is discovered. Maybe it doesn't, or the sensor was bypassed or silenced, and the pump explodes. I'm rambling, but this is a real world example. My point is that these various factors: designed safety monitors like sensors or fail-safes play hand in hand with over-engineered systems as well as the security of the control systems. Any one part of the system should not be allowed to lapse or be less secure with the idea that another level of the system will catch the problem before it becomes life endangering.

ezconnect 6y ago

I agree on this, if something bad happened most critical system are designed to break somewhere to limit the catastrophe, or other times they are over engineered 1,000x because sometimes you can never tell what nature can do to your system.

TeMPOraL 6y ago
I wish to believe that. I'd expect it of good engineers. However, I don't trust systems to remain as robust as initially designed, after decades of undergoing constant pressure to reduce costs, make things more (fiscally) efficient, "cut out fat", etc.
- Arrath 6y ago
  Even the loss of institutional knowledge can degrade the safety of a system over time. Ever had to start maintaining a codebase after the greybeard who made it retired? Did you have any documentation to go off of? Anyone remaining in the company regard it as anything other than a production critical black box? Now imagine that codebase is an industrial process, with 20 years of growth, add-ons, changes. Probably some mismatching control systems, and god only knows if the as-builts or red line plans for the additions are all correct or rectified with each other..
Arrath 6y ago
Certainly the systems are designed to. But over the operational life, things happen. Systems degrade, maybe maintenance lapses a bit. Maybe, for example, a mechanic tired of trouble shooting an issue replaces the 9th blown burst disc in a row with one he just cut from the mud flap on his shop truck. NBD, the system was only running 5% over pressure anyway and he wants to go home. Later, this overpressure state backs up through the system and overheats a pump which, considering that it is pumping liquid explosives, isn't ideal. Maybe this trips a temperature sensor and the jury rigged burst disc is discovered. Maybe it doesn't, or the sensor was bypassed or silenced, and the pump explodes. I'm rambling, but this is a real world example. My point is that these various factors: designed safety monitors like sensors or fail-safes play hand in hand with over-engineered systems as well as the security of the control systems. Any one part of the system should not be allowed to lapse or be less secure with the idea that another level of the system will catch the problem before it becomes life endangering.