Hi T Judah


You kind of need to understand the old rules to understand the new time frame. In the Old code a locomotive has 48 months of operating time between major inspections of the boiler barrel that was (and still is) facilitated by the tube removal. If you did not operate 48 months within 60 months you were required to do the barrel inspection anyway. The barrel inspection is to determine the effects of corrosion on the barrel of the boiler. A significant number of locomotive failures were barrel failure due to cracking or pitting.

It is my understanding that the 1472 day time frame came out of the old code. If you take 1472 days and divide it by 365 you get 4 years at 365 days and 12 spare days. If you take 1472 and divide it by 15 you get 98 .13333333 days per year. Now if you look at the old code again for flue extensions where the bottom flues were removed and the barrel inspected where the most corrosive damage is anticipated before the locomotive was allowed to operate for 1 year before looking at the interior again either by flue extension or full barrel inspection. In the post steam era, flue extensions became more common and the full barrel was not inspected at the same intervals as during regular steam operations.

It is interesting to note that many museums under the old rule would loose a whole month if they operated one weekend and they had to do a monthly inspection for that month. To give them more flexibility the new code introduced the idea of service days. By committee decision it was decided that you should be forced to check the entire boiler for thickness conditions every 15 years and have it start 1 calendar year from the day you rolled your first tube into the boiler.

I hope this helps

Robby Peartree