TM 55-1930-209-14&P-2 Table 4-3.  Seawater System Troubleshooting (Cont'd) Problem Probable Cause Suggested Action 10.   Seawater  not  draining  from ballast tank a. Ballast   tank   drain   valve(s)   SW7 and/or SW8 closed a. Open valve(s) SW7 and/or SW8 closed b. Overboard  discharge  valve  SW18 closed b. Open valve SW18 c. Seawater not flowing to discharge valve c. Troubleshoot    seawater    supply    lines    as given in problem 5, b thru e d. Piping clogged d. Unclog piping 11.   Generator  cooling  seawater intake    pressure    not    high enough a. Seachest blocked a. Blowdown aft seachest (paragraph 3-3.8.2) 12.   Seawater not flowing through generator to discharge valve SW49 a. Seachest valve SW37 not open a. Open valve SW37 b. Seawater strainer clogged b. Switch    to    alternate    strainer    and    clean clogged strainer (paragraph 4-7.2.3) c. Generator  supply  valve(s)  SW38, SW40, SW41, and/or SW42 c. Open valve(s) SW38, SW40, and/or SW42 d. Generator discharge valve(s) SW39, SW41 and/or SW43 closed d. Open valves SW39, SW41, and/or SW43 e. Overboard  discharge  valve  SW49 closed e. Open valve SW49 f. Piping clogged f. Unclog piping NOTE Due to this vessel's mission and crew capabilities, maintenance normally assigned to unit level or higher echelons of maintenance may be assigned to the crew. 4-7 Seawater system.    This  section  describes  lubrication  and  repair  of  the  seawater  system  involving  repair  parts listed in Appendix G of TM 55-1930-209-14 & P-18. WARNING Shut down seawater system before attempting any repair.  Be sure to open circuit breakers. Redtag circuit breakers with: "WARNING - DO NOT ACTIVATE. REPAIRS BEING MADE." 4-7