Transcript
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Pipe Material Selection
Pipe materials include:
1. Steel pipes2. GI pipes3. HDPE4. PVC5. Ductile Iron Pipe (DIP)6. Reinforced Concrete Pressure Pipe (RCPP)7. Asbestos-Cement Pipe (ACP)
Buried piping for municipal water transmission and distribution must resist internal pressure,
external loads, differential settlement, and corrosive action of both soils and, potentially, the
water it carries. General factors to be considered in the selection of pipe include the following:
Service conditions
Pressure (including surges and transients)
Soil loads, bearing capacity of soil, potential settlement
Corrosion potential of soil
Potential corrosive nature of some waters
Availability
Local availability and experienced installation personnel
Sizes and thicknesses (pressure ratings and classes)
Compatibility with available fittings
Properties of the pipe
Strength (static and fatigue, especially for water hammer)
Ductility
Corrosion resistance
Fluid friction resistance (more important in transmission pipelines) Economics
Cost (installed cost, including freight to job site and installation)
Required life
Cost of maintenance and repairs
In summary the selection of pipe materials is based on
carrying capacity strength ease of transportation and handling
availability quality of water cost (initial and maintenance)
Valves are required:
to isolate segments of a pipeline, e.g. Gate and butterfly valves to regulate rate of flow, e.g. Check valves prevent backflow of water to control pressure (Pressure sustaining valves (PSV) and Pressure reducing valves (PRV))
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to allow release or entry of air from pipe system (Air-release and vacuum valves)Factors considered in the selection of valves include:
purpose and operation, capacity required, head loss and rate of flow, cost, Availability, etc.
Purpose of Distribution reservoirs
Equalizing supply and demand Increasing operating convenience Leveling out pumping requirements Providing water during source or pump failure Maintaining pressure levels within acceptable ranges Providing water to meet fire demands Increase detention times Blending water sources
Distribution reservoir types
Ground reservoirs Buried reservoirs Elevated reservoirs Stand pipes
o Can be made of Concrete or masonryo Steel tank
Distribution reservoirs design considerations and details
Minimum capacity: Equalizing storage + Emergency reserve (about 25%) + Firestorage.
Location: provide several smaller storage units Aesthetics: visual impacts Ventilation Overflow Security and safety
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HARDCROSS METHOD (HCM)
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