Hydrostatic Testing on the Superheater Tubes

Advancement on the No. 28 project-


Pressurizing superheater tubes.

A hydrostatic test was conducted on all 21 superheater elements. 300 lbs. of pressurized water was applied to determine if there were any leaks. Steam engine Superheaters were engineered to increase efficiency by transforming saturated steam into dry steam.  Saturated steam moves from the throttle valve through the dry pipe into the superheater header attached to the tube sheet in the smoke box. This steam then passes through elements which are housed in the superheater flues. Combustible gasses from the firebox move through the tubes and heat the water and the steam inside of the superheater element.  At the end of it’s cycle through the elements, it proceeds into a separate compartment of the superheater header into the distribution pipes, then on to the piston valves and then on to the main steam cylinders. Dry “superheated” steam is more efficient than wet saturated  steam.

Superheaters are more expensive and require extra maintenance however the benefits are reduced water and fuel consumption.

Interior view of a superheater unit

Interior view of a superheater unit

Performance of a steam locomotive superheater.

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Warren Smith polishing seats prior to hydrostatic test.

Photo of a hydro test conducted on the super heaters.

Park Volunteers Warren Smith and David Ethier performing the hydrostatic test.


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Superheater tubes awaiting inspection.

Leaks that were found were marked for repair. Only 3 had leaks and were welded to repair.


Tube marked to be repaired

Tube marked to be repaired

After the cleaning, testing, and repairs were completed, the superheater tubes were stored awaiting installation.

Previous Sierra No. 28 Update: Removal of Firebox Pieces for Replacement

Next Step: Fabrication and Installation of Boiler Patches