Service steam (low-pressure) drainage systems collect the uncontaminated drains from low-pressure (below 150 psi) steam piping systems and steam equipment outside the machinery spaces. Space heaters as well as equipment used in the laundry, the tailor shop, and the galley are typical sources of drains for the service steam drainage system. Aboard some ships, these drains discharge into the most conveniently located freshwater drain collecting tank. On other ships, particularly large combatant ships, such as carriers, the service steam drains discharge into special service steam drain collecting tanks located in the machinery spaces. The contents of the service steam drain collecting tanks are discharged to the condensate system. In addition, each tank has a gravity drain connection to the freshwater drain collecting tank and to the bilge sump tank located in the same space.

Notice that the service steam drainage system collects only clean drains that are suitable for use as boiler feed. Contaminated service steam drains, such as those from laundry presses, are discharged overboard. 111Service steam drain system components consist of various pipings, steam traps, valves, and flanges. In the event you need to make repairs on this system, make sure the system is properly tagged. If needed you can request assistance from the Hull Technicians, who are well trained for this job.

HIGH-PRESSURE STEAM DRAIN SYSTEMS

High-pressure drainage systems generally include drains from superheater headers, throttle valves, main and auxiliary steam lines, steam catapults (on carriers), and other steam equipment or systems that operate at pressures of 150 psi or more. The high-pressure drains aboard some ships lead directly into the deaerating feed tank (DFT). Aboard some newer ships, the high-pressure drains empty into the auxiliary exhaust line just before the auxiliary exhaust steam enters the DFT. In either case, the high-pressure drains end up in the DFT.

These systems have basically the same components as the low-pressure steam drain systems. Components specifically designed for high-pressure steam and the addition of orifices are the only major differences. Whichever system is to be repaired, the system must be tagged. When dealing with repairs on both low-pressure and high-pressure steam systems, there should be a controlled work procedure package. You should review the QA manual concerning repairs on steam systems. Remember you can request assistance from the personnel who are trained to do the repairs. For more general information concerning steam plants, read Boiler Technician 3&2, NAVEDTRA 10535-H.

DISTILLING PLANTS

This section will deal with inspections, troubleshooting, and repairing of low-pressure steam distilling plants. The two most common types used by the Navy are the submerged-tube and the flash-type distilling plants. Additionally, this section will mention some facts about the heat recovery type of distilling plant the Navy also uses.