CHAPTER 14 



PIPING, FITTINGS, AND VALVES 



This chapter deals with pipe, tubing, fittings, 

 valves, and related components that make up 

 the shipboard piping systems used for the trans- 

 fer of fluids. The general arrangement and lay- 

 out of the major engineering piping systems is 

 discussed in chapter 9 of this text; in the present 

 chapter, we are concerned with certain practical 

 aspects of piping system design and with the 

 actual piping system components— pipe, tubing, 

 fittings, and valves. 



DESIGN CONSIDERATIONS 



Each piping system and all its components 

 must be designed to meet the particular condi- 

 tions of service that will be encountered in 

 actual use. The nature of the contained fluid, 

 the operating pressures and temperatures of 

 the system, the amount of fluid that must be 

 delivered, and the required rate of delivery 

 are some of the factors that determine the ma- 

 terials used, the types of valves and fittings 

 used, the thickness of the pipe or tubing, and 

 many other details. Piping systems that must 

 be subjected to temperature changes are de- 

 signed to allow for expansion and contraction. 

 Special problems that might arise— water ham- 

 mer, turbulence, vibration, erosion, corrosion, 

 and creep,! for example— are also considered in 

 the design of piping systems. 



The requirements governing the design and 

 arrangement of components for shipboard piping 



iThe term creep is used to describe a special kind of 

 plastic deformation that occurs very slowly, at high 

 temperatures, in metals under constant stress. Be- 

 cause creep occurs very slowly— so slowly, in fact, 

 that years may be required to complete a single 

 creep test— the importance of this type of plastic 

 deformation was not recognized in many fields of 

 engineering until fairly recently. Creep-resisting 

 steel is now used in most modern naval boilers 

 and for most high temperature piping. 



systems are covered in detail by contract 

 specifications and by a number of plans and 

 drawings. The information given here is not 

 intended as a detailed listing but merely as a 

 general guide to the design requirements of 

 shipboard piping systems. 



All shipboard piping is installed in such a 

 way that it will not interfere with the operation 

 of the ship's machinery or with the operation 

 of doors, hatches, scuttles, or openings covered 

 by removable plates. As far as possible, piping 

 is installed so that it will not interfere with the 

 maintenance and repair of machinery or of the 

 ship's structure. U piping must be installed in 

 the way of machinery or equipment which re- 

 quires periodic dismantling for overhaul, or if 

 it must be installed in the way of other piping 

 systems or electrical systems, the piping is 

 designed for easy removal. Piping that is vital 

 to the propulsion of the ship is not installed 

 where it would have to be dismantled in order 

 to permit routine maintenance on machinery 

 or other systems. Piping is not normally in- 

 stalled in such a way as to pass through voids, 

 fuel oil tanks, ballast tanks, feed tanks, and 

 similar spaces. 



Valves, unions, and flanges are carefully 

 located to permit isolation of sections of piping 

 with the least possible interference to the con- 

 tinued operation of the rest of the system. The 

 type of valve used in any particular location 

 is specified on the basis of the service con- 

 ditions to be encountered. For example, gate 

 valves are widely used in locations where 

 the turbulent flow characteristics of other 

 types of valves might be detrimental to the 

 components of the system. 



Unnecessary high points and low points are 

 avoided in piping systems. Where high points 

 and low points are unavoidable, vents, drains, 

 or other devices are installed to ensure proper 



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