PRINCIPLES OF NAVAL ENGINEERING 



look almost exactly alike from the outside, they 

 may respond very differently to pressures, 

 temperatures, and other service conditions. 

 Therefore, each kind of pipe and tubing can be 

 used only for the specified applications. 



PIPE FITTINGS 



Pipe or tubing alone does not constitute a 

 piping system. To make the pipe or tubing into 

 a system, it is necessary to have a variety of 

 fittings, connections, and accessories by which 

 the sections of pipe or tubing can be properly 

 joined and the flow of the transferred fluid may 

 be controlled. The following sections of this 

 chapter deal with some of the pipe fittings most 

 commonly used in shipboard piping systems; 

 these fittings include unions, flanges, expansion 

 joints, flareless fluid connections, steam traps, 

 strainers, and valves. 



UNIONS 



Union fittings are provided in piping systems 

 to allow the piping to be taken down for repairs 

 and alterations. Unions are available in many 

 different materials and designs to withstand 

 a wide range of pressures and temperatures. 

 Figure 14-1 shows some commonly used types 

 of unions. 



FLANGES 



Flanges are used in piping systems to allow 

 easy removal of piping and other equipment. 

 The materials used and the design of the flanges 

 are governed by the requirements of service. 

 Flanges in steel piping systems are usually 

 welded to the pipe or tubing. Flanges in nonfer- 

 rous systems are usually brazed to the pipe 

 or tubing. 



EXPANSION JOINTS 



of sliding expansion joint depends upon the 

 specific design of the joint. 



Flexing-type expansion joints are those in 

 which motion is absorbed by the flexing action 

 of a bellows or some similar device. There 

 are various kinds of flexing-type expansion 

 joints, each kind being designed to suit the 

 requirements of the particular system in which 

 it is installed. Figure 14-2 illustrates the gen- 

 eral principle of a bellows-type expansion joint. 



Expansion joints are not always used in 

 piping systems, even when allowance must be 

 made for expansion and contraction of the piping. 

 The same effect can be achieved by using direc- 

 tional changes and expansion bends or loops. 



FLARELESS FLUID CONNECTIONS 



A special flareless fluid connection has re- 

 cently been developed for connecting sections 

 of tubing in some high pressure shipboard sys- 

 tems. This fitting, which is generally known as 

 the bite-type fitting , is very useful for certain 

 applications because it is smaller and lighter 

 in weight than the conventional fittings previously 

 used to join tubing. The bite-type fitting is used 

 on certain selected systems where the tubing 

 is between 1/8 and 2 inches in outside diameter. 



The bite-type fitting, shown in figure 14-3, 

 consists of a body, a ferrule or sleeve that 

 grips the tubing, and a nut. The fitting is not 

 used in places where there is insufficient space 

 for proper tightening of the nut, in places where 

 piping or equipment would have to be removed 

 in order to gain access to the fitting, or in 

 places where the tubing cannot be easily de- 

 flected for ready assembly or breakdown of the 

 joint. The fitting is sometimes used on gage 

 board or instrument panel tubing, provided the 

 gage board or panel is designed to be removed 

 as a unit when repairs are required. 



STEAM TRAPS 



Expansion joints are used in some piping 

 systems to allow the piping to expand and con- 

 tract with temperature changes, without damage 

 to the piping. Two basic types of expansion 

 joints are used in shipboard piping systems: 

 sliding-type joints and flexing-type joints, 



Sliding-type expansion joints include sleeve 

 joints, rotary joints, ball and socket joints, 

 and joints made up of some combination of these 

 types. The amount of axial and rotary motion 

 that can be abosrbed by any particular type 



Steam traps are installed in steam lines to 

 drain condensate from the lines without allow- 

 ing the escape of steam. There are many dif- 

 ferent designs of steam traps, some being suit- 

 able for high pressure use and others being 

 suitable for low pressure use. In general, a 

 steam trap consists of a valve and some device 

 or arrangement that will cause the valve to 

 open and close as necessary to drain the con- 

 densate from the lines without allowing the 

 escape of steam. Steam traps are installed at 



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