wamtp,
I recommend that the first thing you do is bring in some competent Piping Designers and a Piping Engineer.
Then they need to start taking a lot of pictures of EVERYTHING, piping, equipment, support steel, ALL PIPE SUPPORTS, instrumentation, electrical etc. Those pictures will become invaluable once the fire damaged piping has been demo'd. If you don't have up-to-date drawings of your plant, have the piping designers make sketches of all lines before demo.
Now that you have that started, you need to find out exactly what Corp. means by "rebuild." I was involved in a refinery fire rebuild a number of years ago and "rebuild" meant to duplicate the existing plant regardless of whether some systems were poorly designed. Unless it was a safety issue, it went back in just like it was. The philosophy was to keep engineering hours and down time to an absolute minimum.
If your company is willing to spend a little extra time and money to improve the facility over what it was then that's great. The existing layout, drawings, photos and sketches will still be good starting point. As the others have suggested, talk with the operators, maintenance folks and plant engineers to find out what needs to be improved as well as what was already working great. This may also be a good time to address any de-bottlenecking issues.
It's very unfortunate about the fire and I hope nobody was injured. You need to address what caused the fire and certainly take care of that issue everywhere there may be a risk.
The fire rebuild that I was involved in was started because a corroded hydrocarbon line burst open and that hydrocarbon found an ignition source. Parallel to the fire re-build effort, they checked the piping for the entire unit and eventually needed to replace more pipe due to being corroded beyond its retirement thickness than what was damaged in the fire.
To me, this situation is an ever increasing concern as we see facilities remain in service for many years beyond there original design life. Process and feed changes can also reduce the life of a system. Continued good maintenance and inspection practices are the key to identifying systems that need attention before they become a problem.
Good luck with your facility.
NozzleTwister
Houston, Texas