Steel 55 gallon barrels used as smoker drums can really go the distance if cared for properly.  In regard to weathering it doesn’t take much to protect them from the elements.  Keeping them covered when not in use will help prevent them from rusting or corroding.  The paint or coating we give them does a really great job at preventing overall rust.  One of our fully built drums was left uncovered in the rain by accident one time for 2 or 3 days.  When we discovered it we noticed that it was fine and without any rust.  In terms of scrapes and scratches the paint or coating will only stand up to so much abuse.  If you’re hard on it and throw it around a lot, move it around roughly, bump it into things or not secure it during transit allowing it to fall and slide around, then yeah you’ll do damage.  Steel is durable and is relatively difficult to dent with normal usage.  You have to literally crash it into something hard in order to put a dent in it.  Good thing is if that were to happen you could probably hammer the dent out, and touch up the paint if necessary.  The interior bottom of the barrel is largely protected by the ash catcher built into the charcoal basket.  So, hot coals and ash are not just sitting on the metal at the bottom of the barrel.  Very little ash makes contact with any grease drippings or moisture left behind during a cook.  So, this helps prevent any sort of metal corrosion created by combining ash and moisture.  Also, if you drop it, it won’t crack.  It might dent in the place where it lands depending on the height you dropped it from, but it won’t crack or break.  More info about the durability of 55 gal barbecue smokers