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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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