Valves, Pipe fittings and piping.txt

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berazil
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140051
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Valves, Pipe fittings and piping.txt
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2012-03-06 14:47:34
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Navy Exam
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Navy Exam
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    • author "me"
    • fileName "Valves, Pipe fittings and piping"
    • tags "navy Exam"
    • description "Navy Exam"
    • What is the function of the check valve?
    • The permit the flow of fluid in one direction only.
  1. A gate valve is an example of what class of valves.
    Stop valves
  2. What is the most common stop valve.
    Globe valve
  3. What is the purpose of a bridgewall marking on the globe valve?
    Indicate the direction of the flow.
  4. What type of valve is always open or always closed, and does not regulate fluid flow?
    Gate valve
  5. What is meant by the term rising stem gate valve?
    Both the gate and the stem move upward when the valve is opened.
  6. What prevents gate valves used in high pressure steam systems from binding?
    Flexible gates
  7. What are the disks and seats of valves used in high temperature steam systems surfaced with?
    Stellite
  8. What type of valve is shaped to hold a cylindrical or tapered plug?
    Plug valve
  9. What are plug valves commonly used for?
    Petckoks on auxiliary machinery
  10. What type of valve is a combination gate valve and plug valve?
    Piston valve
  11. What determines the tightness of a piston valve?
    The closeness of fit between the piston and the inside of the cylinders.
  12. What type of valve is used to make relatively fine adjustments?
    Needle valve
  13. What is the needle valve installed on an auxiliary turbine used for?
    As an overload nozzle
  14. What type of valve is light in weight, takes up less space than a gate or globe valve, and is relatively quick acting.
    Butterfly valve
  15. How far must a butterfly valve be rotate to open or close the valve.
    1/4 turn or 90 degrees
  16. What type of seat does a butterfly valve have?
    Resilient
  17. What type of check valve, does the disk move up and down in response to changes in the pressure of incoming fluid?
    Lift check
  18. What type of check valve, does the disc move in an arc to open or close the valve?
    Swing check
  19. On a stop check valve, the maximum lift of the disk is controlled by?
    The position of the valve stem.
  20. What type of valve opens automatically when the pressure in the line or in the unit becomes too high.
    Relief valve
  21. What prevents a relief valve from lifting at normal operating pressure?
    Spring tension
  22. How are relief valves set?
    By the adjusting screw or adjusting nuts.
  23. At what pressure does the combination exhaust relief valve lift?
    2 psi abobe auxiliary exhaust line pressure.
  24. What type of valve, gives an audible warning to the operator, when it lifts?
    Sentinel valve
  25. What the two opposing forces oa a spring-loaded reducing valve?
    1- The downward force of the spring

    2- The upward force of the steam pressure.
  26. On spring loaded reducing valve, what determines the position of the auxiliary valve?
    Position of the controling diaphragm.
  27. Automatic unloading valves are installed to exhaust to what major components?
    Main and auxiliary condenser.
  28. What is the function of the unloading valve?
    to discharge steam from the auxiliary exhaust line to the condenser wheneever the auxiliary exhaust exceeds 15 psi.
  29. what component is used when is necessary to take suction from one of several sources and discharge to another unit or several units of the same or a separate group?
    Valve manifold
  30. What allows an operator to operate certain valves from distant locations?
    Remote operating gear.
  31. What is the cooling source of the inline desuperheater?
    Feedwater
  32. What device is stalled in steam lines to drain condesate from the lines without allowing steam to escape?
    Steam trap
  33. What type of steam traps are considered to be mechanical traps?
    Ball float and bucket-type
  34. How is the operation of a bellows type steam trap controlled?
    By the expansion of the vapor of a volatile liquid which is enclosed in the bellows.
  35. What type of steam trap operates under the principle the hot water under pressure flashes into steam when the pressure is reduced?
    Impulse
  36. What is the only moving part in an impulse steam trap?
    The disk
  37. Constant flow drain orificies are used in what systems?
    150 psi or above, where condensate load and pressure remain near constant.
  38. What type of steam trap relies on variable density of condensate?
    Orifice.
  39. What type of steam trap uses dissimilar metals to operate?
    Bimettalic
  40. Where can installation and other information be found pertaining to flange shields?
    NSTM 505
  41. What are the two types of piping expansio joints used onboard ships?
    Sliding and flexible kind.
  42. What type of piping expansion joint absorbs motion by the movement of a bellows or some similar device?
    Flexible type
  43. What does a valve that has a marking on the body 2000 WOG indicate?
    Valve is suitable for water, oil or gas service at 2000 psi.
  44. How is tubing identified in the Navy?
    By outside diameter (OD) and by the actual measured wall thickness.
  45. What is the composition of copper- nickel alloy tubing used onboard surface ships?
    90% copper and 10% nickel
  46. What are the two classes of packing and gasket joints?
    Moving and fixed
  47. What type of joint uses gasket material?
    Fixed
  48. What type of joint uses packing material?
    Moving
  49. A fixed joint is identified by the first digit int he symbol number, which would be?
    Two
  50. A moving joint is identified by the first digit in the symbol number, which would be?
    One
  51. What is used to identify each type or style of packing and gaskets?
    Symbol number.
  52. What does the second digit of the symbol number indicate?
    Packing or gasket composition.
  53. How can practically all shipboard packing and gasket problems be solved?
    By proper selection from the packing and gasket chart.
  54. Low pressure packing must never be used to pack what type of system valves?
    High pressure
  55. What type of packing is constructed of 100 % graphite
    Corrugated Ribbon Packing (CRP)
  56. What lubricates the CRP?
    Graphite
  57. What kind of warning stickers must be affixed to all corrugated ribbon containers?
    Warning: CRP conducts electricity.
  58. What is the purpose of using graphite filament yarn (GFY) for the first and last packing rings on valves packed with corrugated ribbon?
    They are used as anti-extrusion rings to prevent the corrugated ribbon packing from being forced out of the stuffing box.
  59. What systems do not use corrugated ribbon packing?
    Fuel oil and lube oil sytems.
  60. How is the outlet temperature of the inline desuperheater controlled?
    By termostatic and diaphragm control valves.
  61. Where can detailed information on the selection of insulation, lagging, and fastening be found?
    NSTM 635
  62. A tubular product is called pipe if its size is identified by what?
    Iron Pipe Size (IPS) and by the reference to wall thickness schedule of piping.
  63. How are flanges installed in nonferrous systems?
    By brazing
  64. How are steel flanges installed?
    By welding
  65. What does a red sealant on lagging cloth indicate?
    The material is asbestos free
  66. When removing lagging, if you are unsure of what material you are working with, who should you contact immediately?
    Your supervisor
  67. On ships with steam atomization, what is used to lag the atomization piping at the burner front?
    Epoxy coating.
  68. What are the positions of the combination exhaust relief valve?
    Normal, Relief and Safety
  69. What position of the combination relief valve is used when performing turbine overhaul?
    Safety position

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