Union Pacific 5511, a 2-10-2 “TTT-6” steam locomotive, has passed a hydrostatic test according to Railroading Heritage of Midwest America. This marks another major step in its restoration.

Earlier this month, the locomotive’s boiler was filled with water for the first time in 70 years. Over the course of four days, the boiler was heated to 120 degrees using propane and electric heaters. This comes after the locomotive had a new front tube sheet installed early this year along with new tubes and flues.

5511’s maximum allowable working pressure is 200 PSI, but the Federal Railroad Administration requires that the water in a hydrostatic test be pressurized 1.25 times higher than the MWAP, meaning that the water was pressurized to 250 PSI. 

The group passed the hydro test on 5511 under FRA inspection, allowing the group to move on to the next goal in the restoration, which is a live steam test. 

RRHMA intends to complete the FRA-witnessed steam test within the upcoming winter season. 

Locomotive 5511 was built in 1923 by the Baldwin Locomotive Works to haul heavy freight trains on the UP system. After being removed from active service in 1956, the locomotive served as a stationary boiler in both Ogden, Ut. and Green River, Wyo. 

In December 1958, it was used in the filming of UP’s documentary Last of The Giants, which covered the final years of operation for the railroad’s 4-8-8-4 Big Boy locomotives. 5511 was no longer in service by this point, and the engine was attached to a string of freight cars with a diesel pushing at the rear while tires were burned in the smokebox to create the illusion of a working steam locomotive. 

The locomotive was stored in Green River until 1968 when it was moved to Cheyenne, Wyo. Union Pacific donated the locomotive to Railroading Heritage of Midwest America in 2022.

-Nick Stewart