You should carry out pump operation and safety precautions according to the Engineering Operational Procedures (EOP), a subsystem of the Engineering Operational Sequencing System (EOSS), if your ship has EOSS, or the Naval Ships Technical Manual and the instructions posted on or near each individual pump. Follow the NAVSEA technical manual or MRCs (for PMS related maintenance) for all maintenance work.

VALVES

Every piping system must have some means to control the amount and direction of the flow of a liquid or a gas through the lines. This is accomplished by the use of valves, which can be opened or closed as required. All valves can be grouped in two general classifications: (1) man-ually operated valves and (2) automatic valves. Manually operated valves include all valves that are adjusted by hand. Automatic valves in-clude check valves, thermostatic valves, and pressure-regulating valves. (Thermostatic valves were discussed in chapter 7 of this training manual.) This section contains general informa-tion only. You should refer to the appropriate NAVSEA valve manuals if you should require more specific information.

Valves are usually made of bronze or steel. Steel valves are either cast or forged and are made of either plain steel or alloy steel. Alloy steel valves are used in high-pressure, high-temperature systems. The disks and seats (internal sealing sur-faces) of valves used in steam piping systems are usually coated with a chromium-cobalt alloy known as Stellite, which is an extremely hard metal.

Bronze valves are never used in systems where temperatures exceed 550F. Steel valves are used for all services above 550F. Bronze valves are used almost exclusively in systems that carry salt water. The seats and disks of these valves are usually made of Monel, a metal that has excellent corrosion- and erosion-resistant qualities.