I’m beginning to think that this makes the most sense. Any idea how I would go about confirming this? I haven’t a clue.
Study copy of ASME Boilers I with section PL (locomotive boilers) commencing around p.161.
https://studylib.net/doc/26070157/asme-bpvc-2021-section-1-pressure-vessel-code-workbook
The relevant current language you want is 49 CFR 230.24(b) which establishes ‘not less than a factor of 4’.
Also see the NBIC (National Boiler Inspection Code)revised every odd year (so no revision this year) and maintained by the National Board of Boiler Inspectors
Note the NBIC Committee - Working Group, Locomotive Boilers. You may see some familiar names who would be good resources for some of the questions you have.
Next NBIC meeting is in Louisville July 15th-18th - reservation required, but free.
I have now moved away from the original question (did the ICC and ASME rules for boilers differ during the age of steam construction? Yes) and to a more nebulous question. If the ICC rules were less stringent and would give you a locomotive of superior performance to a ASME engine for the same weight, why did the majority of roads build to ASME specs?
A 300 PSI engine built to ICC rules would definitionally be less expensive on the front end than one built to ASME as you have a .5 factor of safety lower (so less material) and can use higher tensile strength in the calculations if you have material test data. And if you built to the same boiler thickness (assume the same boiler on both engines, just one is going by ICC rules) the ICC engine will have much higher allowable pressure and will be a greater benefit to the railroad in terms of hauling.
So why did the majority of roads pick the more expensive, less efficient standard to build to?
I’m currently trying to chase down the boiler insurance hypothesis without much luck. May be better to start a new thread as I now have a new question.
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