Plumbing work02 -Basic Types of Pipe and Fittings

       
                  Pipes are used in water supply systems to deliver water from one place to another. Water flaws through pipes by:
Gravity or
Force pumping

For efficiency, pipes must deliver water with least friction. For this reason pipes are usually circular and the inner surface is made smooth. Man has used many materials for the manufacture of pipes. In the first instance bamboo trunks were used as pipes by boring through the nodes. Then pipes were made by twisting lead sheet around circular timber. Later hot drawn, cold drawn or seam welded pipes were manufactured from metals like copper, steel, stainless steel, aluminum and brass etc. In large water supply installations pipes made out of:-
Cast iron
Black iron
Concrete
Asbestos were used.

A major disadvantage of these pipes was that they are heavy and joining was complicated. During World War 2 the necessity for a more flexible and convenient pipe type was felt and the result was the synthetic polymer pipe.

Polymer Pipes - The advantages of polymer pipes are:
a) Easily moulded to any shape or size
b) Easy to work with and are light weight
c) High resistance to weathering and corrosion
d) Almost maintenance free
e) Good electrical, sound and heat insulation
f) Withstand moisture, oils and acids.

Plastics (polymers) are mainly divided into 02 groups:-

• Thermoplastics - which become soft on heating and returning back to its original form on cooling

• Thermosetting plastics - which undergo chemical changes on heating and do not return to original form on cooling

Polymer (plastic) pipes are a petroleum bi-product. Two main plastics are used in the manufacture of pipes namely:-
– PVC (Poly Vinyl Chloride)
– HDPE (High Density Polyethylene)

PVC is identified as a rigid pipe while HDPE is identified as a flexible pipe. Polymer pipes are manufactured by extrusion or moulding.

Pipe Fittings
Pipes cannot always be installed as straight runs. They need to:-
a) Change direction
b) Branch off
c) Reduce or enlarge in size
d) Connect to appliances

These need special pipe components which are named pipe fittings. There are various pipe fittings used for the different requirements and locations:
Bends (90˚ or oblique), Elbows, Reducers, Tees (equal/unequal), Sockets (Plain/valve/faucet), Union couplings

 

Union coupling                                               Elbow 

                            

Tee                                                                  Bend

‘Y’ junction

Valves and Taps (or faucets)

Valves and taps (faucets) are required in pipe systems to control flow. Flow control includes - Increase flow, Decrease flow, Stop flow or Open flow.

•      Different types of valves are used.

                     

Gate Valve                                                                          Bib Tap

             

Working mechanism – Bib tap                                                                      Globe valve

                  

Working mechanism – Globe valve                       Working mechanism – Gate valve

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