Principles of naval engineering - Historic Naval Ships Association

PRINCIPLES OF NAVAL ENGINEERINGjunction of interconnecting systems. Short runsof piping which serve an immediately obviouspurpose, such as short vents or drains, need notbe marked. As a rule, piping on the weather decksdoes not require marking; if it does requiremarking, label plates (rather than stenciledpaint or prepainted vinyl labels) are used.Each valve is marked on the rim of the handwheel,on a circular label plate secured by thehandwheel nut, or on a label plate attached to theship's structure or to adjacent piping. The valvelabel gives the name and purpose of the valve, ifthis information is not immediately apparentfrom the piping system marking, and it gives thelocation of the valve. The location is indicated bythree numbers which give, in order, the verticallevel, the longitudinal position, and the transverseposition. Consider, for example, a drainbulkhead stop valve that is labelled:2-85-1The location of this valve is indicated by thesenumbers. The first number indicates the verticalposition— in this case, the second deck. The secondnumber indicates the longitudinal position bygiving the frame number— in this case, frame 85.The third number indicates the transverse position—starboardside if the number is odd, portside if the number is even. The numbers indicatingtransverse position begin atthecenterlineofthe ship and progress out toward the sides. Forexample, a second drain bulkhead stop installedon the same level and at the same frame, but fartherto starboard, would be indentified as2-85-3In either case, of course, the valve would alsobe identified as to system (DRAIN BULKHEADSTOP, in these examples) if the piping systemidentification did not make the system obvious.A slightly different system of marking is usedfor identifying main line valves, cross-connectionor split-plant valves, and remote-operatedvalves in vital engineering piping systems. Insteadof being identified bylocation, these valvesare assigned casualty control identification numbers,by system, asMain steam MSI, MS2, MS3, etc.Auxiliary steam ASl, AS2, ASS, AS4, etc.Auxiliary condensate. . . ACNl, ACN2, etc.Auxiliary exhaust AEl, AE2, AE3, etc.Fuel oil service FOSl, FOS2, etc.On newer ships, the system for markingvalves in the vital engineering systems is slightlydifferent, consisting of a three-part designationin the following sequence: (1) a number designatingthe shaft or plant number; (2) lettersdesignating the system; and (3) a number, or acombination of a number and a letter, indicatingthe individual valve. Individual valve numbersare assigned in sequence, beginning at the originof a system and going in order to the end of thesystem, excluding branch lines. In other words,the first valve in the mainline is No. 1, the secondis No. 2, and so forth. Since parallel flowpaths frequently exist, it is often necessary toassign a shaft number and a system designationto the parallel flow paths as well as to the basicmain line of the system. The valves in the parallelflow paths are then numbered in sequence;identical numbers areusedfor valves which performlike functions in each of the parallel flowpaths, but a letter suffix is added to distinguishbetween the similar valves. This system of identificationis illustrated for part of a 'main steamsystem in figure 9-11.It is of utmost importance that all engineeringpersonnel (officer and enlisted) become familiarwith the valve markings used in the vitalengineering systems. Use of the identificationnumbers tends to prevent confusion and errorwhen the plant is being split or cross-connectedand when damaged sections are being isolated,since it provides a means of ordering any particularvalve to be opened or closed without takingtime to describe the actual physical location ofthe valve. However, the identification markingscannot serve their intended purpose unless allengineering personnel are throroughly familiarwith the physical location and the identificationnumber of each valve they may be requiredeither to operate themselves or to order openedor closed.Most shipboard piping is painted to match andblend in with its surrounding bulkheads, overheads,or other structures. In a very few systems,color is used in a specified manner to aidin the rapid identification of the systems. Forexample, JP-5 piping in interior spaces ispainted purple. Gasoline valves in interiorspaces are painted yellow, except for movingparts of the valves; in exterior locations, partof the valve handwheel or the operating lever Ispainted yellow. Green is similarly used to identifyoxygen, and red is used for fireplugs andfoam discharge valves.204