7.4 Mechanical Fundamentals - 7.4 Mechanical Fundamentals Flashcards

1
Q

Three types of Piping

A

High Pressure/Temp.
Low Temp.
Seawater/Potable Water

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2
Q

Piping identification (>3/8”)

A

Measured by Inside Diameter (ID)
Designated by wall thickness

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3
Q

Tubing identification (< 3/8”)

A

Measured by Outside Diameter (OD)
Designated by wall thickness

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4
Q

Pipe Marking

A

Spaced not more than 15 feet apart; if concealed, not more than 5 feet apart
Name of the system (standard DC abbreviation may be used)
Specific service
Direction of flow

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5
Q

Pipe Marking classifications

A
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6
Q

Pipe hangars and supports

A

Designed to support weight of the piping, fluid, and insulation

Three types:
Rigid (fixed)
Spring
Resilient

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7
Q

Rigid (fixed)

A

Supports provide restraint in at least one direction; generally used in cold piping systems

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8
Q

Spring

A

Supports are used where necessary to permit pipe movements due to thermal expansion, contraction, or movement of the ship
Pictures

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9
Q

Resilient

A

Used to prevent noise radiated from shipboard equipment from interfering with ship sonar, and to prevent the noise from being radiated into the water

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10
Q

Insulation and Lagging

A

Used to prevent heat transfer from piping that is hotter or cooler than surrounding atmosphere

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11
Q

Valves

A

Control the flow of the contained fluid

Direct the flow of the contained fluid

Include several different types and sizes depending on application and controlling factors of the specific system

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12
Q

Globe valve

A

Used in steam, air, oil, and water lines

Common globe valve types:
Straight flow
Angle flow
Cross flow

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13
Q

Needle valve

A

Used to make relatively fine
adjustments in the flow of fluid;
allow more precise control of
flow than can be obtained with
an ordinary globe valve

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14
Q

Gate Valve

A

Acts like opening or closing a gate to
allow/stop flow and used when a
straight line flow of fluid or a
minimum flow restriction are required

Common gate valve types:
Rising Stem
Non-rising Stem

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15
Q

Ball Valve

A

Used in seawater, sanitary, trim and drain, air, hydraulic, and oil transfer systems

Uses a ball inside the valve to start and stop the flow of fluid

Common ball valve types:
Quick acting valve
Planetary gear valve

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16
Q

Butterfly Valves

A

Light weight, relatively small, and quick acting. Used in low pressure, low temp systems

-Valve seats are replaceable:
Lapping, grinding, or machine work not required
-Provide positive shut off
-Used in low pressure, low temperature systems

17
Q

Check Valves

A

Prevents the fluid in a system from flowing in the wrong direction

-Operated by the flow of fluid in the piping
-Common types of check valves:
Swing check
Lift check
Ball check
-Stop check valves are used on drain lines, on discharge side of many pumps

18
Q

Relief Valves

A

Protect piping system from excessive pressure

Designed to open when the preset lift pressure is reached and close when the pressure drops slightly below the lifting pressure
Can be lifted by hand for testing purposes

19
Q

Sentinel Valves

A

Small relief valves installed in some systems to warn of impending over-pressurization

Actions must be taken quickly by watch standers to secure the piece of equipment or system and prevent damage from the increased pressure

20
Q

Pumps

A

Devices which utilize an external source of power to apply a force to a fluid and transfer it from one place to another
Subject to cavitation

21
Q

Positive displacement

A

Pumps displace a specific quantity of fluid regardless of resistance to flow (head)

Constant flow (given constant speed regardless of pressure/flow resistance)
Require a relief valve
Viscous fluids (lube oil, hydraulic oil, etc)

Reciprocating
22
Q

Non-positive displacement

A

Pumps displace a variable output of fluid depending on the resistance to flow

Variable flow
Non-Viscous fluids (usually water)
Not necessarily self priming
Vent and recirculation requirements

Centrifugal
23
Q

Positive displacement movement

A

Reciprocating
-Diesel fuel injectors
-Emergency feed
-HPACs
Rotary
-Air
-Oil
Moving Vane
Variable stroke
-Steering

24
Q

Non-positive displacement movement

A

Propeller
-Gas turbine axial flow compressor
-Circulating water
-Main circulating water (on steam ships)
Jet
-Eductors (firemain driven)
-Air ejectors (steam driven)
Centrifugal
-Water
-Firemain
-Chill Water
-Potable Water
-Sea Water