Surviving 'FDp20' class (formerly IS class) plinthed near Kiev main station.
In the early 1930s, the Soviet Union introduced two modern, large locomotive classes. The 'FDp20' was a 2-8-4 intended for passenger working with 1850 m.m. diameter coupled wheels whilst the 'FD' was generally similar but arranged as a 2-10-2 with smaller coupled wheels intended for freight duties.
The passenger class was originally called the 'IS' class (for Iosif Stalin) and the freight class was called 'FD' (for Feliks Dzerzhinski). However, in 1962 (when Stalin became persona non grata the 'IS' class was quietly re-named 'FDp' where the 'p' indicated 'passazhirskii'.
I saw the only surviving 'FDp20', number 578, in Ukraine in 2005 when I went with my friend Mike (now, alas, passed on) on a steam driving holiday which is briefly described here and with a set of pictures (including the two pictures of the 'FDp' in this post) here. The surviving 'FDp20' is displayed on a very elaborate welded steel plinth outside the passenger locomotive repair works near the centre of Kiev in the Ukraine.
Front view of surviving 'FDp20' class. Note that the complete smokebox front is hinged on the left and, once unbolted, can be swung open for re-tubing and access to the tubeplate. There is a smaller door in the smokebox front used for char removal. This door is hinged on the right and secured by 14 'dogs' or clamps which, when tightened, ensure that the smokebox door is airtight.
For technical specifications, refer to Reference 1.
References:
Reference 1: 'Soviet Locomotive Types - The Union Legacy' by A J Heywood & I D C Button (Frank Stenvalls Forlag) ISBN 0-9525202-0-6.