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  • MILIND SATPUTE PIPING GUIDE

    PIPING INTERVIEW QUESTIONNAIRE

    COMPRESSORS

    1 What are the types of compressors? Ans : Positive Displacement, Centrifugal and Axial, rotary screw, rotary vane, rotary lobe, dynamic, liquid ring compressors. 2 What are types of compressor drives? Ans : Electric motor, gas turbine, steam turbine and gas engine. 3 How Centrifugal compressors work ? Ans : Highspeed impellers increase the kinetic energy of the gas, converting this energy into higher pressures in a divergent outlet passage called a diffuser. Large volume of gas at moderate pressure. 4 What are types of steam turbine and why are they popular? Ans : Condensing and non-condensing, Popular because can convert large amounts of heat energy into mechanical work very efficiently. 5 Where gas turbine drive is used ? Ans : Desserts and offshore platforms where gas is available, for gas transmission, gas lift, liquid pumping, gas re-injection and process compressors. 6 What are the auxillary equipments of compressor? Ans : Lube oil consoles, Seal oil consoles, Surface condensers, Condensate pump, Air blowers, Inlet air filters, Wast heat system, compressor suction drum, knock out pot, Pulsation dampner, volume bottles, Inter and after coolers. 7 What are the types of seal oil system? Ans : Gravity and pressurized. 8 What factors to be considered while designing compressor housing? Ans : Operation, Maintenance, Climate conditions, Safety, Economics. 9 What are the compressor housing design points? Ans : Floor elevation, building width, building elevation, hook centerline elevation. 10 What are the types of compressor cases? Ans : Horizontal split case, Vertical split case. 11 What are compressor suction line requirements? Ans : Minimum 3D straight pipe between elbow and inlet nozzle, increases based on inlet piping layout. 4D

  • MILIND SATPUTE PIPING GUIDE 12. What are necessary parts of inlet line of compressor? Ans : Block Valve, Strainer, Break out flanges in both inlet and outlet to remove casing covers, Straightening vane in inlet line if not enough straight piece in inlet line available, PSV in interstage line and in discharge line before block valve. 13. What points to be considered for reciprocating compressor piping layout? Ans : High pulsation, simple line as low to grade as possible for supporting, analog study, all branches close to line support and on top, Isolate line support from adjacent compressor or building foundations 14. What are the types of compressor shelters? Ans : On ground with no shelter, Open sided structure with a roof, Curtain wall structure (Temperate climates), Open elevated installation, Elevated multicompressor structure.

    DRUMS

    1 What are drum internals? Ans : Demister pads, Baffles, Vortex breakers, Distribution piping. 2 What are drum elevation requirements? Ans : NPSH, minimum clearance, common platforming, maintenance, operator access. 3 What are drum supports? Ans : Skirt for large drums, legs, lugs, saddles for horizontal drums. 4 What are necessary nozzles for non-pressure vessel? Ans : Inlet, outlet, vent, manhole, drain, overflow, agitator, temperature element, level instrument, and steamout connection. 5 What are necessary nozzles for pressure vessel? Ans : Inlet, outlet, manhole, drain, pressure relief, agitator, level guage, pressure gauge, temperature element, vent and for steamout. 6 What is preferred location for level instrument nozzles? Ans : Away from the turbulence at the liquid outlet nozzle, although the vessel is provided with a vortex breaker, instrument should be set in the quiet zone of the vessel for example on the opposite side of the weir or baffle or near the vapor outlet end.

  • MILIND SATPUTE PIPING GUIDE 7 What is preferred location for process nozzles on drum? Ans : Minimum from the tangent line.

    1. What is preferred location for steam out nozzle on drum? Ans : At the end opposite to the maintenance access.

    2. What is preferred location for vent ? Ans : AT the top section of drum at the end opposite the steam out connecton.

    3. What is preferred location for pressure instrument nozzle on drum? Ans : Must be anywhere in the vapor space, preferable at the top section of drum

    4. What is preferred location for temperature instrument? Ans : Must be in liquid space, preferably on the bottom section of drum.

    5. What is preferred location for drain? Ans : Must be located at the bottom section of drum.

  • MILIND SATPUTE PIPING GUIDE

    PIPING INTERVIEW QUESTIONNAIRE

    PUMPS

    1 What is NPSH ? Ans : It is measure of the pressure drop of the liquid as it moves form the inlet of the pump to the eye of the impeller, determined by testing and expressed in feet of water by pump manufacturer. 2 What is cavitation ? Ans : Cavitation is a rapid collapse of vapor pressure that can produce noise, result in loss of head and capacity and create a severe erosion of the impeller and casing surface in the adjacent inlet areas. 3 What is velocity head? Ans : The head loss caused by the consumed power to accelerate stationary fluid to suction line velocity during pump startup. Its about 1 ft. 4 What is standard for petroleum pumps? Ans : API 610 is the standard for centrifugal pumps in petroleum industry. 5 Where positive displacement pumps are used ? Ans : Used to move viscous liquids, injects chemicals or additives into a system, or pump quantities too small for centrifugal pumps. 6 What are types of rotary pumps ? Ans : External Gear, Cam and piston, two lobe, three lobw, single screw, Two screw. 7 Where rotary pumps are used ? Ans : For viscous liquids that are free of hard and abrasive fluids. 8 Where should boiler feed water pumps be located ? Ans : They take water from a deaerator and generally operate close to the vapor pressure of the liquid, hence they must be located as close to the deaerator as possible. 9 Tell something about vertical pumps ? Ans : Used where low available NPSH is not sufficient, for surface condenser, for waste material in concrete pit, screen at the bottom. 10 Where centrifugal pumps in vacuum service be located ? Ans : directly below tower, may be on spring supports. 11 How to support discharge line of centrifugal pump ? Ans : Discharge line should be supported as close to the top elbow as possible and should be within five diameters of that elbow, using spring support.

  • MILIND SATPUTE PIPING GUIDE 1 How suction line is supported? Ans : Commonly supported under the elbow adjacent to the pump nozzle. 2 How the suction line reducer should be placed ? Ans : It should be placed top flat. 3 What are suction line requirements? Ans : To flat reducer, strainer, block valve, no pockets, as short as possible with consideration to stress, min straight length of 3D. 4 What are the requirements of discharge piping? Ans : Reducer, Pressure indicator, check valve, block valve, min. stress, support at top elbow. 5 What is accepted distance between pumps? Ans : 1200 MM / 4 feet. 6 What is special requirement for discharge line of positive displacement pump? Ans : Relief valve whose discharge is connected in suction line between the isolating valve and the pump.

    REACTOR

    1. Tell about reactor? Ans : Heart, mixing, chemical reaction, heat generated-absorbed, agitation, jacket, heating coils, cooling.

    FURNACES

    1 Where furnaces shall be located ? Ans : Furnaces shall be located upwind or side wind of process units to blow any combustible leaks away from the open flame, Min 90M away from tanks and 30M away from control room. 2 What should be stack height? Ans : Stack height shall be minimum 6M above working platform in the vicinity of 25m radius.

    SPIRAL HEAT EXCHANGERS

  • MILIND SATPUTE PIPING GUIDE 1 Where spiral heat exchangers are used? Ans : Generally in chemical plants 2 How piping is positioned for spiral heat exchanters ? Ans : Piping positioned to allow opening of covers and the removal plates.

    SHELL AND TUBE HEAT EXCHANGERS

    1 What are the types of tube arrangments? Ans : U-tube, Fixed tube, kettle arrangement. 2 What is full form of TEMA? Ans : Tubular exchangers manufacturers Association. 3 Which fluids to be sent through tubes? Ans : Fouling and/or corrosive fluids (Easy cleaning and cheaper to replace tubes than shell), hotter fluid : To reduce heat loss to the surroundings except steam., refrigerant, cooling fluid. 4 What should be clearance between flanges of exchangers? Ans : 1000 MM.

    PLATE EXCHANGERS

    27. Where plate exchangers are used ? Ans : Low pressure, low temperature applications.

    DOUBLE PIPE OR FIN TUBE EXCHANGERS

    28. Where used ? Ans : Used when liquid has a greater resistance to heat flow than another or when the surface area is small.

    AIR COOLER EXCHANGERS 29. Where used ? Ans : To cool tower overhead vapors.

  • MILIND SATPUTE PIPING GUIDE LPG STORAGE

    1 How to group LPG Vessels ? Ans : Max 6 Vessels, total capacity 15,000 cum, curb wall, distance between vessels of different groups 30M, separate dedicated manifold for each group. 2 Where to located LPG Storage ? Ans : Downwind of process units, important buildings and facilities, not in same dyke where other flammable liquid HCs stored, single row in case of spheres and bullets, not one above the other, bullet head not toward other vessel, no dip ditch to avoid LPG Settling. 3 How to operate LPG Cylinders ? Ans : Separate area for empty and filled cylinders, Cylinders vertical, not near other gase cylinders, never below grade, smooth trucking traffic.

  • MILIND SATPUTE PIPING GUIDE

    PIPING INTERVIEW QUESTIONNAIRE

    1. What are instrument categories? Ans : General, flow, temperature, pressure, level, density etc.

    2. Which instruments are handled by piping department ? Ans : flame arrestor, breather valve.

    3. What are basic functions of instruments? Ans : To sense, transmit, indicate, read and control.

    4. Why block valve is used at the root of an instrument like pressure indicator?

    Ans : They are needed to isolate gages for maintenance during plant operation and during hydrostatic testing of piping system. They are called root valve. 5. Where diaphragm assembly is used ?

    Ans : For corrosive, abrasive, viscous fluids. Neutral fluid like glycol is used on instrument side of diaphragm.

    6. Where and why bleed valve is used in instruments ? Ans : If the conveyed fluid is hazardous or under high pressure, a branch fitted with a bleed valve is inserted between the gage and its isolating valve, to relieve pressure and /or drain the liquid before servicing the gage. It can also be used to sample or for adding a comparison gage.

    7. Why control valves are usually flanged? Ans : For ease of installation and removal during maintenance.

    8. Where ball control valve is used? Ans : Suitable where nature of fluid is slurry form or handling two phase flow having particle in suspension, for non-critical and critical fluids having a fluid temperature to suit the soft seat material and where relatively low pressure drop is required across control valve. They have side mounted actuator.

    9. Where butterfly control valve is used ? Ans : Used for large size piping network handling clean fluid for low pressure drop across control valve and soft seated control valve. Metal seated valves used for higher temperatures.

    10. How control valve block valves should be located ? Ans : They should be as close to control valve as possible, considering drain requirement and handwheel clearance. At least one of the block valve should be placed in vertical so that spool can be removed allowing the control valve to be removed.

  • MILIND SATPUTE PIPING GUIDE

    11. How TSO valve should be installed ? Ans : Tight shut off (TSO) valve or reduced port ball contrl valve should be installed in vertical for gas service and horizontal ok for liquid service.

    12. How bypass valve in control station should be located? Ans : Near inlet branch point, not above control valve, with 200mm clearance between actuator and valve.

    13. How control station should be supported ? Ans : It should be supported such that control station piping is self supporting even if the control valve is removed. Normally, on exit side elbows of bottom run of control valve.

    14. Why and where drain should be located in control valve assembly ? Ans : Drain is used to drain the piping between two block valves on two sides of control valve before removing control valve for maintenance. It must be located at lowest point of bottom run. One drain is used if control valve is fails open, and two drain used if control valve fails close, as both sides are blocked in this case. For one drain, it should be upstream side of control valve.

    15. Where reducer shall be located in control valve assembly ? Ans : As close as possible to control valve, preferably directly welded control valve flanges.

    16. How breakup flanges for control valve should be located ? Ans : One vertical and one horizontal which is achieved by having one block valve in vertical leg of control valve inlet. Do not place support on inlet elbow.

    17. What are the types of flow measuring devices? Ans : Orifice plate, Variable area flow meter i.e. rotameter, magnetic flow meter, turbine flow meter, positive displacement meter.

    18. What is piping and instrument scope of supply for orifice meter ? Ans : Piping provided gaskets and bolts and tapping from orifice plate to two block valves. Instrument provides orifice plate and flange assembly and connection down stream of block valves.

    19. How orifice flange taps should be oriented ? Ans : For liquid and steam, it should be horizontal or 45 degree down from horizontal on both sides. For gas and vapor lines, it should be vertical or 45 to vertical on both sides. Taps are 0.5 inch.

    20. What are straight run requirements of orifice plate ? Ans : Inlet straight run requirement can be 15D to 20D and outlet straight run requirement 5D min. It depends on piping configuration and d/D ration i.e. ration of inside dia of orifice plate and pipe. It is to be confirmed with instrument engineer in instrument specification of

  • MILIND SATPUTE PIPING GUIDE project.

    21. What are straight run requirements for vortex meters? Ans : 5D upstream.

    22. Where restriction orifice plates are used ? Ans : For effective distribution of fluid in piping network.

    23. What are types of level measurement? Ans : Direct and inferential

    24. What are direct methods of level measurement? Ans : Gauge glasses, reflex or transparent, calibrated tapes or dip sticks placed in vessel and calibrated directly in level or volume.

    25. What are inferential methods of level measurement? Ans : Hydrotatic head, buoyancy, conductance, radiation, float.

    26. What is hydrostatic head type level transmitter.? Ans : Installed directly on nozzle, uses pressure sensing assembly to get the level. Diaphragm type used for liquids with solids.

    27. What are pressure instruments used in chemical industries? Ans : Manometers, bourden tubes, bellows and diaphragms.

    28. What are manometers? Ans : Single or U type glass tube with mercury or other fluid. Inclined tube for very low pressure measurement used.

    29. What are types of bourdon tubes? Ans : C, the spiral and helical, most widely used since 100 years.

    30. What are temperature measuring instruments? Ans : Thermocouples, resistance temperature detectors, filled system, bimetallic thermometer, thermowells.

    31. What thermocouple metals normally used? Ans : Iron + Constantine, Chromel + Alumel etc.

    32. How resistance thermocouples work ? Ans : Electrical resistance of a conductor changes with temperature.

    33. How filled system temperature element work ? Ans : Bourdon tube, filled with liquid, liquid expands, bourdoun tube indicates on scale temperature.

    34. How bimetallic thermocouple work ? Ans : Different expansion of different metals bends the bimetallic strip to indicate temperature. Invar and Nickel pair used.

    35. What is minimum pipe size required for thermowell installation? Ans : 3

  • MILIND SATPUTE PIPING GUIDE

    RACK

    36. What are design considerations for pipe rack ? Ans : Rack width, no of levels and elevations, bent spacing, pipe flexibility, Access and maintenance of each item in pipe rack.

    37. What are steps in rack design? Ans : Generate line routine diagram, Calculate bent spacing, set width of rack, decide elevations and levels.

    38. What is pipe bent? Ans : Pipe bent consists of a vertical column or columns and a horizontal structural member or members that carry piping systems, usually above the headroom.

    39. What factors affect pipe span? Ans : Size, Schedule, liquid or vapor, insulated or bare pipe.

    40. What are spandrels? Ans : Horizontal structural members located along the longitudinal centerline that are used for structural stability, pipe support or intermediate pipe bents.

    41. Which lines placed where in rack ? Ans : Process lines on lower level, utility lines on top level, instrument and cable trays on utility level or separate topmost level, Heavy lines near columns, Flare line outside rack on cantilever beams or inside rack above top level , steam lines with expansion loops on one side of rack, line s with orifice runs on one side of rack beside columns for maintenance using portable ladder.

    42. How much extra space required for rack ? Ans : 20 % extra for future lines.

    43. How to route steam lines on rack ? Ans : Steam headers on top level or rack, determine growth by multiplying coefficient (From nomograph) of expansion by length of line. Try anchor in middle, determine growth of each branch and see weather the have enough flexibility, if not anchor at th distance on both sides, determine amount of expansion leg from nomograph, and decide loop size. Line that require largest expansion leg should be located on the outside of the loop.

  • MILIND SATPUTE PIPING GUIDE

    INSULATION

    44. What insulating materials are used ? Ans : Asbestos, calcium silicate, cellular glass, cellular silica, diatomaceous silica plus asbestos, Mineral fiber, mineral wool, magnesia, polyeurothene foam.

  • MILIND SATPUTE PIPING GUIDE PIPING INTERVIEW QUESTIONNAIRE

    1 What factors to consider for site selection? Ans : District classification, Transportation facilities, Manpower availability, industrial infrastructure, community infrastructure, availability of raw water, effluent disposal, availability of power, availability of industrial gas, site size and nature, ecology and pollution. 2 What are different standards? Ans : Most commonly use standards are as follows: 3 What are various temporary closures for lines? Ans : Line blind valve, line blind, spectacle plate, double block and bleed, blind flanges replacing a removable spool. 4 Where jacked screwed flange is used ? Ans : For spectacle discs, one flange is jacked screw flange. This flange has two jacked screws 180 degree apart which are used to create sufficient space between flange for easy removal and placement of line blind or spectacle blind. 5 What is double block and bleed? Ans : Two valves with bleed ring in between with a bleed valve connected to the hole of bleed ring. Sr. Standard Description 1. ANSI B18.2 Square and hexagola head bolts and nuts 2. ANSI B16.3 Malleable iron threaded fittings 3. ANSI B16.4 Cast iron threaded fittings. 4. ANSI B16.9 Steel buttwelding fittings 5. ANSI B16.11 Forged steel socketwelding and threaded fittings 6. ANSI B16.25 Buttwelding ends 7. ANSI B16.28 Short elbow radius and returns 8. MSS-SP-43 Stainless steel buttweld fittings 9. MSS-SP-83 Pipe Unions 10. API 605 Large diameter carbon steel flanges 11. ANSI B16.1 Cast iron pipe flanges and flanged fittings 12. ANSI B16.5 Steel pipe flanges and flanged fittings 13. ANSI B16.47 Large diameter steel pipe flanges and flanged fitts. 14. ANSI B16.20 Ring joint gaskets and grooves for pipe flanges 15. ANSI B16.21 Non metallic gaskets for pipe flanges 16. API 601 Metallic gasket for refinery piping. 17. API 5L Specification for line pipe. 18. ANSI B16.10 Welded and seamless wrought steel pipes 19. ANSI B36.19 Welded and seamless austenitic stainless steel pipe 20. ANSI B16.10 Face to face and end to end dimensions of valves 21. ANSI B16.34 Steel valves, flanged and buttwelding ends.

  • MILIND SATPUTE PIPING GUIDE

    6. Where blind flange is used ? Ans : It is used with view to future expansion of the piping system, or for cleaning, inspection etc.

    TOWERS

    1 What are crude oil ranges? Ans : Crude oil BP Range: 100F-1400F, lightest material: Butene below 100F, Heavier materials- upto 800F, Residue above 800F. 2 What is batch shell process? Ans : feed, heat,condense,heat more,condense, low quality. 3 What are types of towers? Ans : Stripper, Vacuum tower, trayed, packed towers. 4 What is chimney tray? Ans : Its a solid plate with central chimney section, used at drawoff sections of the tower. 5 What factors to consider while setting tower elevation? Ans : NPSH, Operator access, Maintenance access, Minimum clearance, reboiler type , common area, type of support, Tower dimensions, type of head, bottom outlet size, foundation details, minimum clearances. 6 How to located tower maintenance access nozzles ? Ans : At bottom, top and intermediate sections of tower, must not be at the downcomer section of tower and in front of internal piping. 7 How to located feed nozzle ? Ans : Must be oriented in specific area of tray by means of internal piping. 8 How to located temperature and pressure instruments ? Ans : Temperature in liquid space, at downcomer side and pressure in vapor space, in area except downcomer sector.

  • MILIND SATPUTE PIPING GUIDE PIPING INTERVIEW QUESTIONNAIRE

    1. What are the steps in selection of valve? Ans : What to handle, liquid, gas or powder, fluid nature, function, construction material, disc type, stem type, how to operate, bonnet type, body ends, delivery time, cost, warranty.

    2. What are functions of valves? Ans : Isolation, regulation, non-return and special purposes.

    3. What are isolating valves? Ans : Gate, ball, plug, piston, diaphragm, butterfly, pinch.

    4. What are regulation valves? Ans : Globe, needle, butterfly, diaphragm, piston, pinch.

    5. What are non-return valves? Ans : check valve,

    6. What are special valves? Ans : multi-port, flush bottom, float, foot, pressure relief, breather.

    7. What materials are used for construction of valves? Ans : Cast iron, bronze, gun metal, carbon steel, stainless steel, alloy carbon steel, polypropylene and other plastics, special alloys.

    8. What is trim? Ans : Trim is composed of stem, seat surfaces, back seat bushing and other small internal parts that normally contact the surface fluid.

    9. Which standard specifies trim numbers for valve ? Ans : API 600.

    10. What are wetted parts of valve? Ans : All parts that come in contact with surface fluid are called wetted parts.

    11. What is wire drawing? Ans : This term is used to indicate the premature erosion of the valve seat caused by excessive velocity between seat and seat disc, when valve is not closed tightly.

    12. What is straight through valve? Ans : Valve in which the closing operation of valve is achieved by 90degrees turn of the closing element.

    13. What pressure tests are carried out on valves? Ans : Shell-hydrostatic, seat-hydrostatic, seat-pneumatic

  • MILIND SATPUTE PIPING GUIDE 14. What are available valve operators?

    Ans : Handlever, handwheel, chain operator, gear operator, powered operator likes electric motor, solenoid, pneumatic and hydraulic operators, Quick acting operators for non-rotary valves (handle lift).

    15. What are two types of ball valve? Ans : Full port design and regular port design, according to type of seat, soft seat and metal seat.

    16. What are ball valve body types? Ans : Single piece, double piece, three piece, the short pattern, long pattern, sandwitch and flush bottom design.

    17. Why ball valves are normally flanged? Ans : Because of soft seat PTFE which can damage during welding.

    18. What are butterfly valve types? Ans : Double flange type, wafer lug type and wafer type.

    19. What are types of check valve? Ans : Lift check valves and swing check valves.

    20. What are non-slam check valves? Ans : Swing check valve, conventional check valve, wafer check valve, tilting disc check valve, piston check valve, stop check valve, ball check valve.

    21. Where stop check valve is used ? Ans : In stem generation by multiple boilers, where a valve is inserted between each boiler and the main steam header. It can be optionally closed automatically or normally.

    22. Where diaphragm valves are used ? Ans : Used for low pressure corrosive services as shut off valves.

    23. What is Barstock Valve? Ans: Any valve having a body machined from solid metal (barstock). Usually needle or globe type.

    24. What is BIBB Valve? Ans: A small valve with turned down end, like a faucet.

    25. What is Bleed Valve? Ans: Small valve provided for drawing off liquid.

    26. What is BlowDown Valve? Ans Refers to a plug type disc globe valve used for removing sludge and sedimentary matter from the bottom of boiler drums, vessels, drip legs etc.

  • MILIND SATPUTE PIPING GUIDE

    27. What is Breather Valve? Ans: A special self acting valve installed on storage tanks etc. to release vapor or gas on slight increase of internal pressure ( in the region of to 3 ounces per square inch).

    28. What is Drip Valve? Ans: A drain valve fitted to the bottom of a driplet to permit blowdown.

    29. What is Flap Valve? Ans: A non return valve having a hinged disc or rubber or leather flap used for low pressure lines.

    30. What is Hose Valve? Ans: A gate or globe valve having one of its ends externally threaded to one of the hose thread standards in use in the USA. These valves are used for vehicular and firewater connections.

    31. What is Paper-Stock Valve? Ans: A single disc single seat gate valve (Slide gate) with knife edged or notched disc used to regulate flow of paper slurry or other fibrous slurry.

    32. What is Root Valve? Ans: A valve used to isolate a pressure element or instrument from a line or vessel, or a valve placed at the beginning of a branch form the header.

    33. What is Slurry valve? Ans: A knife edge valve used to control flow of non-abrasive slurries.

    34. What is Spiral sock valve? Ans: A valve used to control flow of powders by means of a twistable fabric tube or sock.

    35. What is Throttling valve? Ans: Any valve used to closely regulate flow in the just-open position.

    36. What is Vacuum breaker? Ans: A special self-acting valve or nay valve suitable for vacuum service, operated manually or automatically, installed to admit gas (usually atmospheric air) into a vacuum or low-pressure space. Such valves are installed on high points of piping or vessels to permit draining and sometimes to prevent siphoning.

    37. What is Quick acting valve ? Ans: Any on/off valve rapidly operable, either by manual lever, spring or by piston, solenoid or lever with heat-fusible link releasing a weight which in falling operates the valve. Quick acting valves are desirable in lines

  • MILIND SATPUTE PIPING GUIDE conveying flammable liquids. Unsuitable for water or for liquid service in general without a cushioning device to protect piping from shock.

    38. What is diverting valve ?

    Ans : This valve switch flow from one main line to two different outlets. WYE type and pneumatic control type with no moving part.

    39. What is sampling valve? Ans : Usually of needle or globe pattern, placed in branch line for the purpose of drawing all samples of process material thru the branch.

    40. What are blow off valve? Ans : It is a variety of globe valve confirming with boiler code requirements and specially designed for boiler blowoff service. WYE pattern and angle type, used to remove air and other gases from boilers etc.

    41. What is relief valve? Ans : Valve to relieve excess pressure in liquids in situations where full flow discharge is not required, when release of small volume of liquid would rapidly lower pressure.

    42. What is safety valve? Ans : Rapid opening(popping action) full flow valve for air and other gases.

    43. What is foot valve? Ans : Valve used to maintain a head of water on the suction side of sump pump, basically a lift check valve with integrated strainer.

    44. What is float valve? Ans : Used to control liquid level in tanks, operated by float, which rises with liquid level and opens the valve to control water level. It can also remove air from system, in which case, air flows out of system in valve open condition, but when water reaches valve, float inside valve raises to close the valve and stop flow of water. Used in drip legs.

    45. What are flush bottom valves? Ans : Special type of valves used to drain out the piping, reactors and vessels, attached on pad type nozzles.

    46. What are types of flush bottom valves? Ans : Valves with discs opening into the tank and valves with disks into the valve.

    47. What are the uses of three-way valve? Ans : Alternate connection of the two supply lines to a common delivery vise versa, isolating one safety valve, division of flow with isolation facility.

  • MILIND SATPUTE PIPING GUIDE

    48. What are uses of four way valve? Ans : Reversal of pump suction and delivery, By pass of strainer or meter, reversal of flow through filter, heat exchanger or dryer.

    49. What is metal seated lubricated plug valve? Ans : A plug valve with no plastic material, where grease is applied to contacting surfaces for easy operation.

    50. What are three patterns of plug valve design? Ans : Regular pattern, short pattern and ventury pattern

    51. What is regular pattern plug valve? Ans : Rectangular port, area almost equal to pipe bore, smooth transition from round body to rectangular port, for minimum pressure loss.

    52. What are short pattern plug valve? Ans : Valves with face to face dimension of gate valve, as a alternative to gate valve.

    53. What are ventury pattern plug valve? Ans : Change of section through the body throat so graded to have ventury effect, minimum pressure loss.

    54. What are inverted plug design valve? Ans : Plug valve with taper portion up of plug. For 8 and higher size.

    55. What is pressure balanced plug valve? Ans : With holes in port top and bottom connecting two chambers on top and bottom of plug, to reduce turning effort.

    56. What are Teflon sleeved plug valve? Ans : PTFE sleeve between plug and body of valve, low turning effort, minimum friction, temperature limitation, anti static design possible.

    57. What are permasil plug valve? Ans : Plug valves with Teflon seat instead of sleeves, for on off applications, can handle clean viscous and corrosive liqiuids, Graphite seat for high temperature applications. Drip tight shut off not possible.

    58. What are eccentric plug valve? Ans : Off center plug, corrosive and abrasive service, on off action, moves into and away from seat eliminating abrasive wear.

    a. 59. What is dimensional standard for plug valve? Ans : API 599.

    59. What is pinch valve?

    Ans : Similar to diaphragm valve, with sleeves of rubber or PTFE, which

  • MILIND SATPUTE PIPING GUIDE get sqeezed to control or stop the flow, Cast iron body, for very low service pressures like isolation of hose connections, manufacture standard.

    60. What is needle valve? Ans :Full pyramid disc, same design as globe valve, smaller sizes, sw or threaded, flow control, disc can be integral with stem, inside screw, borged or barstock body and bonnet, manufacturers standard.

    61. How to install a globe valve ? Ans : Globe valve should be installed such that the flow is from the underside of the disk, Usually flow direction is marked on the globe valve.

    62. What are globe valve port types? Ans : Full port: More than 85% of bore size, Reducer port: One size less than the connected pipe.

    63. What are globe valve disk types? Ans :Flat faced type for positive shutoff, loose plug type for plug renewal or needle type for finer control.

    64. What are characteristics of globe valve stem? Ans : Always rising design, with disk nut at the lower end and handwheel at upper end.

    65. What are types of globe valve? Ans : Angle globe valve, plug type disc globe valve, wye-body globe valve, composite disc globe valve, double disc globe valve.

    66. What is angle globe valve? Ans : Ends at 90 degree to save elbow, higher pressure drop.

    67. Where plug type disc globe valve is used? Ans : For severe regulating service with gritty liquids such as boiler feedwater and for blow off service.

    68. Where WYE body globe valve is used ? Ans : In line ports with stem emerging at 45 degree, for erosive fluids due to smoother flow pattern.

    69. What is double disc globe valve ? Ans : Has two discs bearing on separate seats spaced apart, on a single shaft, for low torque, used for control valves.

  • MILIND SATPUTE PIPING GUIDE a. What are port types for gate valves?

    Ans : Full port and reduced port. Default is reduced bore. Full port has to be specified in bom.

    70. How to close a gate valve ?

    Ans :Turn the handwheel in clockwise direction.

    71. What is lantern ring? Ans : Its a collection point to drain off any hazardous seepages or as a point where lubricant can be injected, it is in the middle of packing rings.

    72. What are types of gate valves? Ans : Solid plane wedge, solid flexible wedge, split wedge, double disc paralles seats, double disc wedge, single disc single seat gate or slide, single disc parallel seats, plug gate valve.

    73. What are the types of bonnets? Ans : Bolted bonnet, bellow sealed bonnet, screwed on bonnet, union bonnets, A U-bolt and clamp type bonnet, breechlock bonnet, pressure seal bonnet.