How Thick is the Firebox?

Our steam locomotive No.40 is in the midst of its 15 year inspection as mandated by Federal Law. This inspection must be completed before No.40 can operate again.

One of the requirements is for us to recalculate the maximum pressure every part of the boiler can withstand. To make our calculations, we must measure the actual thickness of all parts of the boiler and firebox. An Ultra-Sonic Thickness Tester is used to make the hundreds of measurements.

Here, Kjell measures a portion of the firebox. The numbers seen are the thicknesses he has found.

The numbers for each portion of the boiler will be compiled and the lowest values will be used in the calculations. The weakest part of the boiler divide by four (the allowance for safety) will determine the Maximum Allowed Working Pressure (MAWP), for No. 40's next term of service. - J. David