PRINCIPLES OF NAVAL ENGINEERING 



As shown in figures 14-13 and 14-14, the 

 gate is connected to the valve stem. Turning 

 the handwheel positions the valve gate. Some 

 gate valves have nonrising stems— that is, the 

 stem is threaded on the lower end and the gate 

 is threaded on the inside so that the gate travels 

 up the stem when the valve is being opened. Gate 

 valves with nonrising stems are shown in figure 

 14-13. This type of valve usually has a pointer 

 or a gage to indicate whether the valve is in 

 the open position or in the closed position. 

 Some gate valves have rising stems— that is, 

 both the gate and the stem move upward when 

 the valve is opened. In some rising stem valves, 

 the stem projects above the handwheel when 

 the valve is opened; in other rising stem valves, 

 the stem does not project above the handwheel. 

 A pointer or a gage is required to indicate the 

 position of the valve if the stem does not pro- 

 ject above the handweel when the valve is in 

 the open position. 



Plug Valves 



The body of a plug valve is shaped in such 

 a way that it will hold a cylindrical or tapered 

 plug. Holes or ports in the body line up with 

 the pipe in which the valve is installed. A solid 

 cylindrical plug (or in some cases a plug shaped 

 like a truncated cone) fits snugly into the hollow 

 of the body. The plug is attached to a handle, by 

 means of which the plug can be turned within 

 the body. A passageway is bored through the 

 plug. When the valve is in the open position, the 

 passage in the plug lines up with the inlet and 

 outlet ports of the body, thus allowing fluid to 

 flow through the valve. When the plug is turned 



YOKE SLEEVE 

 NUT 



WHEEL 



GLANO 



BODY 



GUIDE 

 RIB 



38.118 

 Figure 14-13.— Cross-sectional views of 

 gate stop valves (nonrising stem type). 



11.317.2X 

 Figure 14-14.— Cutaway view of gate stop 

 valve (rising stem type). 



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