NZSnowman
I presume you are referring to the relevant fuel transferpipe. Most of the VIIC saddle tanks were used as storage for fuel and not as common ballasttanks.Even the saddleregulatingtanks could be used for fuelstorage to increase the operating range. If this pipe is identified correctly as fueltransferpipe, my suggestion is the pipe leads from the no 1 stb. regulatingtank in the saddle outside the PO mess to the common fuelsupplypipe in the CR. and is normally shut and only used in those cases you carry fuel in the regulatingtank no. 1stb. I hope I understood your question correct, otherwise please revert.
Tore