7.4 Mechanical Fundamentals - 7.4 Mechanical Fundamentals Flashcards
Three types of Piping
High Pressure/Temp.
Low Temp.
Seawater/Potable Water
Piping identification (>3/8”)
Measured by Inside Diameter (ID)
Designated by wall thickness
Tubing identification (< 3/8”)
Measured by Outside Diameter (OD)
Designated by wall thickness
Pipe Marking
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
Pipe Marking classifications
Pipe hangars and supports
Designed to support weight of the piping, fluid, and insulation
Three types:
Rigid (fixed)
Spring
Resilient
Rigid (fixed)
Supports provide restraint in at least one direction; generally used in cold piping systems
Spring
Supports are used where necessary to permit pipe movements due to thermal expansion, contraction, or movement of the ship
Pictures
Resilient
Used to prevent noise radiated from shipboard equipment from interfering with ship sonar, and to prevent the noise from being radiated into the water
Insulation and Lagging
Used to prevent heat transfer from piping that is hotter or cooler than surrounding atmosphere
Valves
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
Globe valve
Used in steam, air, oil, and water lines
Common globe valve types:
Straight flow
Angle flow
Cross flow
Needle valve
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
Gate Valve
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
Ball Valve
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