Appendix VI: Pipe
Water is often needed in locations where none is available. Pipe
can help to meet this need if there is some force available to move water
through it. Gravity and pumps can exert the necessary force on water to cause it
to flow through a pipe. But pipe can be expensive and may not be appropriate for
use in some situations. Where water needs to be transported from one place to
another across the surface of the earth, a simple trough arrangement might work
and be more easily repaired when damaged.
Generally speaking, however, pipe is superior to other water
transportation devices. It is readily available and it can be used for a number
of purposes, besides transporting water. It is commonly used in the casing for
drilled wells and in the drop pipe for pumps. Depending on the material from
which it was made, it can be used to make many handy tools or simple equipment.
NOTE: For pipes laid in the ground, always maintain sufficient
pressure in a completed line of pipe so that water will leak out of any holes.
If pressure around the pipe is greater than that inside it, contaminants from
the ground will be forced into the pipe.
When evaluating possible pipe choices, a number of factors
should be considered. They include:
· pressure. Where necessary, can the pipe withstand the
pressure of the water that will be carried inside it? Computing the actual
pressure is beyond the scope of this manual.
It is sufficient to say here that the pressure of the water is
directly related to the vertical height of the water column above that point.
· pipe connections.
Can the pipe connections be made completely watertight, to prevent unnecessary
loss of water and the entrance of possible contaminants?
· weight. Will you
need special equipment to raise or lower the needed length of pipe?
· possibility of
decay or corrosion. Is the pipe suitable for the ground and water conditions in
which you intend to use it?
B. Pipe Materials
Although an appealing idea considering the widespread
availability of bamboo, in fact bamboo is seldom used as water pipe. This is due
to the fact that it is essentially a temporary solution, requiring considerable
upkeep to keep a well from being contaminated by the rotting of the bamboo
· Bamboo can take
the pressure from a column of water 20m in height, or about 2
· Preserve bamboo
for use as water pipe with oil based paint or varnish to seal it on the outside,
or soak in 5% boric acid and water solution.
NOTE: Boric acid can give water an unpleasant smell for about
· Chisel or drill to
break inner membranes of bamboo.
· Join pieces by
three possible methods:
1) sliding one piece into the next, and then
wrapping the joint with tar-soaked rope;
2) using extra bamboo as interior or exterior coupling and then
wrapping the joint with tar-soaked rope;
3) wrapping cow-hide tightly twice around the joint and sealing
it with two pieces of wire.
· There will be a
three to four year life expectancy if the pipe is carefully
· If chlorine is
used to disinfect the water before it flows through the pipe, allow sufficient
contact time for chlorine to act before the water enters the pipe.
2. Iron or Steel-commonly referred to as "black" pipe
· Iron or steel is
frequently used for water pipe even though it is sometimes subject to rust and
corrosion from the water.
· These materials
are commonly used as casing pipe for drilled wells where the water is not
· Iron and steel are
galvanized to help prevent rust and corrosion. (See next entry.)
3. Galvanized Iron or Galvanized Steel
· Regular iron or
steel pipe is simply coated with a thin layer of zinc when galvanized. This
helps reduce rust and corrosion normal to iron and steel.
· The piping is
joined by threaded connections. The threading process cuts through the zinc
layer. Thus, threads are particularly susceptible to rusting and
· Galvanized iron or
steel is commonly manufactured in metric and English sizes.
· Because this
material is strong, the pipe is also particularly useful in manufacturing many
small tools and pieces of equipment to suit a specific job and
4. Plastic - ABS (Acrylonitrile-Butadiene-Styrene)
· ABS plastic has
excellent impact resistance, even at low temperatures.
· ABS has heat
resistance up to 160°F.
· It has pressure
ratings of 1,000, 1,250 and 1,600 pounds per square inch (p.s.i.), depending on
composition and thickness.
· It possesses
excellent corrosion and chemical resistance to non-oxidizing
· It can be joined
by solvent cementing or by pipe threads where wall thickness is
ABS plastic also presents certain problems:
· It is subject to
attack from organic solvents.
· Direct exposure to
the ultraviolet rays of the sun reduces its strength and elongation properties.
This is a gradual process which is likely to significantly affect the pipe
strength only after months of exposure.
Plastic - PE (Polyethylene)
· There are three
types of plastics, varying from soft to hard. Their rigidity, tensile strength,
surface hardness, softening temperature and chemical resistance increase with
density and molecular weight.
· They have p.s.i.
ratings of 80, 100, 125, and 160, according to composition and
· They are extremely resistant to
· This kind of plastic can be
joined by flaring, using insert fittings, or by heat fusion.
· They are low cost, lightweight and flexible, long
lengths can be coiled.
PE plastic also presents certain problems:
· It has low design
stress and poor rigidity.
· The temperature
limit varies from 100 to 180°E depending on density.
· PE plastic is sensitive to light but can be left in
the open for a month or more
· It is
flammable, although easily extinguished.
American and European polyethylenes have different density ratings.
Plastic - PVC (Polyvinyl Chloride)
· PVC plastic has
excellent strength and rigidity.
· Its p.s.i.
ratings are comparable to those or PE and ABS.
· It is extremely resistant to chemicals and
· It can be joined by heat fusion, by
solvent cement, or by various kinds of mechanical joints.
· It is readily threaded if there is sufficient wall
PVC plastic also presents certain problems:
· It is readily
softened by ether, ketones and chlorinated hydrocarbons.
· It is heavier than PE and ABS.
· Its temperature limit is 150°F.
· However, its many advantages make it widely used as
· Concrete is
usually used to make large culverttype pipe.
· It can be used as well casing or lining if care is
taken to seal successive sections from each other.
6. Fired Clay
· Clay is usually
used to make four inch to six inch drainage tile.
· Unless it is
manufactured with special end fittings, usually a bell and socket, it is not
easily adapted to water transport.
· It is relatively
weak and easily