PRINCIPLES OF NAVAL ENGINEERING 



COVER 



BASKET 

 HANDLE 



BASKET 

 STRAINER 



TO PUMP 

 SUCTION 



STRONGBACK 



INLET FLANGE 



4 WAV PLUG COCK B OUTLET FLANGE 



11.329X 



Figure 14-9.— A. Bilge suction strainer. B. Duplex oil strainer. 

 C. Manifold steam strainer. 



the pressure of fluids and are therefore general- 

 ly called pressure-control valves. Others are 

 identified by names which indicate their general 

 function— as, for example, thermostatic recir - 

 culating valves . The following sections deal first 

 with the basic types of stop valves and check 

 valves and then with some of the more complex 

 special kinds of valves. 



Globe Valves 



Globe valves are one of the commonest types 

 of stop valves. Globe valves get their name 

 from the globular shape of their bodies. It is 

 important to note, however, that other types of 

 valves may also have globe-shaped bodies; 

 hence it is not always possible to identify a globe 

 valve merely by external appearance. The inter- 

 nal structure of the valve, rather than the exter- 

 nal shape, is what distinguishes one type of 

 valve from another. 



The disk of a globe valve is attached to the 

 valve stem. The disk seats against a seating 

 ring or a seating surface and thus shuts off the 



flow of fluid. When the disk is moved off the 

 seating surface, fluid can pass through the valve. 

 Globe valves may be used partially open as 

 well as fully open or fully closed. 



Globe valve inlet and outlet openings are 

 arranged in several ways, to suit varying re- 

 quirements of flow. Figure 14-10 shows three 

 common types of globe valve bodies. In the 

 straight type, the fluid inlet and outlet openings 

 are in line with each other. In the angle type, 

 the inlet and outlet openings are at an angle 

 to each other. An angle-type globe valve is 

 used where a stop valve is needed at a 90° turn 

 in a line. The cross type of globe valve has 

 three openings rather than two; it is often used 

 in connection with bypass piping. 



A globe-type stop valve is shown in cross- 

 sectional view in figure 14-11. Figure 14-12 

 shows a cutaway view of a similar (but not 

 identical) globe valve. 



Globe valves are commonly used in steam, 

 air, oil, and water lines. On many ships, the 

 surface blow valves, the bottom blow valves, 



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