|Wells Construction: Hand Dug and Hand Drilled (Peace Corps, 1980, 282 p.)|
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 segments.
· Bamboo can take the pressure from a column of water 20m in height, or about 2 atmospheres.
· 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 three weeks.
· 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 installed.
· 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 corrosive.
· 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 corrosion.
· 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 location.
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 chemicals.
· It can be joined by solvent cementing or by pipe threads where wall thickness is adequate.
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 thickness.
· They are extremely resistant to chemicals.
· 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 oils.
· 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 thickness.
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 plastic pipe.
· 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 broken.