 |  | Carpentry for Vocational Schools - A Teacher's handbook (GTZ, 252 p.) | ||
 |  | 18. PLUMBING | ||
|  | (introduction...) | ||
| | 18.1. Water pipes | ||
| | 18.2. Plumbing tools | ||
| | 18.3. Plumbing fittings | ||
| | 18.4. Guidelines for plumbing | ||
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TOPIC: 18. PLUMBING
INTRODUCTION: This section teaches students the different types of pipes used in plumbing, tools and fittings as well as guidelines to be followed when doing plumbing work.
OBJECTIVES:
18.1. Students should be able to identify the different types of pipe used for plumbing and their common sizes.
18.2. Students should be able to identify all plumbing tools and describe their characteristics and uses.
18.3. Students should be able to identify all fittings used for plumbing work.
18.4. Students should be able to plan their own water system and construct it.
METHOD:
18.1. Prepare samples of different water pipes and display them in the classroom for students better understanding.
Explain with the aid of a blackboard the uses of the different pipes and give the table with the conversion of pipe diameters from inches to millimetres.
18.2. For this lesson prepare all plumbing tools available and display them in the classroom.
When enough time is available demonstrate how these tools are used correctly. Like cutting and threading pipes.
Prepare photocopies of all plumbing tools for students to glue in their trade theory book.
18.3. All plumbing fittings available are displayed in the classroom.
After distributing prepared photocopies of all plumbing fittings to students explain and demonstrate their use by joining them to a small water system.
Students glue the copies in their trade theory book.
18.4. Prepare photocopies of the diagram of a water system and distribute it to students.
Also prepare all pipes and fittings needed for this system.
Build, with students, this water system by following the numbers of pipes and fittings.
Do not glue it so that it can be disassembled after the lesson and be used again.
NOTE: At the end of this topic prepare at least two worksheets for students to complete as part of their nightstudies. Correct and assess it later.
Plumbing is usually done by a trained plumber or pipe fitter. Because of the many special tools used in plumbing and the wide range of different pipes and water systems, special knowledge is needed to do plumbing properly. However, this chapter will enable you to learn the basics of plumbing, some tools, fittings, pipes and give some guidelines to follow.
Water supply pipes are classified into three basic groups. a) Galvanized steel pipes:
- These pipes have a threaded end to fit to
the threaded fittings.
- Galvanized steel pipes are used for external
plumbing from the tank to the house, underground, under the floor and for
supplying water to outside taps.
Figure
b) Copper pipes:
- These pipes are for solder joints and
flare joint fittings.
- Copper pipes are used for distributing the water
inside, the house to all applications (shower, sinks, toilets) and are mostly
laid in the wall because they are of small diameter and is easy to bend. Copper
pipes are also used for hot water systems.
Figure
c) PVC, or Plastic pipes:
- These pipes are for adhesive fittings or
connections.
- PVC-pipes are best suited for external use, as underground or
sewer pipes.
- PVC-pipes are commonly used in rural areas because they are
much easier to cut and connect than any other pipes and few tools are
needed.
Figure
d) Pipe measurements: - Pipes are always measured by inside diameter usually in inches.
Figure
Pipes are available in sizes of:
½" = 15 mm
¾" = 20 mm
1" =
25 mm
1¼" = 32 mm
1½" = 38 mm
2" = 50 mm
3" = 75 mm
4"
= 100 mm
5" = 125 mm
6" = 150
mm
When planing the plumbing work, you must decide which type of pipes to use. Your choice will depend on the plumbing tools available. As plumbing with steel pipes requires a lot of different tools to cut, bend, thread and join the pipes, it is less practical for village plumbing, because of the high costs of these tools.
Plumbing with PVC-pipes and copper-pipes need only a few tools because pipes need not to be threaded due to the fittings which are either glued (PVC-pipes) or connected with special designed flare connectors (Copper-pipes).
Below follows a list of the most important tools for plumbing with steel, copper and PVC pipes.
a) Hacksaw: - Used for steel, copper and PVC-pipes.
Figure
b) Pipe cutter: - For steel, copper and PVC pipes. Pipe cutters do not remove any metal. The wheel squeezes the metal and forces it ahead of the cutter until the pipe is cut through the wall thickness.
Figure
c) Self-locking, hinged pipe vice: - For steel pipes only. Pipes to be cut or threaded must be held steady and prevented from rotating by holding them in a suitable vice.
Figure
d) Chain pipe vice: - For steel pipes only. These vices are made to hold pipes with outside diameters up to 8" (200 mm). They are mounted on solid benches.
Figure
e) Pipe reamer: - For steel-pipes only.
To remove internal burrs caused by cutting pipes. Several types of tapered reamers are available from ½" to 2" with a cross handle.
Figure
f) File: - File off all the outside burrs of the galvanized steel pipe with a flat bastard file or with a halfround bastard file.
Figure
g) Stock and die:
- For steel pipes only.
These are stock and dies for cutting external threads on bars and small pipes up to 1" .
- The stock is a suitable frame with handles to hold and rotate the die.
Figure
- These dies are used to cut external threads.
Figure
- The die must be set exactly at an angle of 90 degrees to the bar or pipe-end and is pressed firmly against the end while rotating the stock clock wise until -the length of the thread is cut.
- Reverse and rotate the stock carefully anti-clock wise. Then repeat to clean out the thread.
Figure
h) Ratchet stock and die:
- For steel pipes only. It works in the same way as the other model but is adjustable from ½" to 2" and the single cutter can be exchanged.
- It has only one handle and when reversing, the knob has to be turned around.
Figure
Figure
- The length of a pipe thread should be between 15 mm and 35 mm long - depending on the pipe diameter.
i) sealing threads:
- For steel and PVC threads. Threads must be sealed to ensure a completely tight joint between pipe and fitting.
- Hemp string: For steel threads. Wind it in the same direction as the male thread.
Figure
- Seal tape: For steel and PVC threads. If using sealing tape, unroll a sufficient length of tape and wrap it around the male thread as shown.
Figure
j) Stillson pipe wrench:
- It is used for all types of pipes with ½" to 2" diameters.
- The stillson pipe wrench is designed as a heavy duty tool to withstand rough handling and heavy work. The jaws give a immediate and positive grip.
Figure
k) Adjustable spanner: - For tightening or loosening connectors. Available in different sizes for pipe fittings up to 2".
Figure
l) Tube flaring tool set:
- Only for copper pipes. Copper pipe-ends must be flared to fit with the copper ring used by connectors which are tightened with a nut to the pipe.
- The flaring tool consists of two parts. The part in which the pipe is fastened, and the sharp pointed inserter which is forced with a hammer, or with a spindle into the end of the pipe to widen it.
Figure
- This job must be done with accuracy to ensure a sealed joint.
Figure
Fittings are used when installing pipes to go around corners, to join pipes, to reduce the diameter of the pipes and to set taps.
The fitting system for PVC and steel pipes is the same. For steel pipes only steel fittings are used, while for PVC pipes PVC and steel fittings can be used because the threads are the same size. For PVC pipes many fittings can be glued with a "PVC solvent cement".
Male socket threaded
Female socket threaded
Plug
Reducing male socket
Reducing female socket
Bushes
Tee - joint
Cross - joint
Back nut
Union
Double female Ellbow 90 deg.
threaded
Double female Ellbow 45 deg.
threaded
PVC-Ellbow plain
PVC - Ellbow + Inspectioneye
Male - Female Ellbow
Flange
'S'- Trap
'P'- Trap
Floor waste
Floor waste cup pattern
Gate valve
Bip - Cock
Stop - Cock
Hose -
Cock
The most important thing is to make sure the water pressure is sufficient for all taps in the house. To ensure that, the watertank must be at least 500 mm higher than the highest tap in the house (most probably the shower). The more taps there are in a house, the larger the tank outlet must be to be able to reduce the pipe diameter after every second tap.
Figure
Description:
1. 1" galv. pipe two end threaded
2. 1"
Gate valve
3. 1" PVC connector male thread, female glued
4. 1" PVC
pipe
5. 1" galv. Union
6. 1" PVC Tee-joint
7. ¾" PVC pipe
8.
¾" PVC Tee-joint
9. ½" PVC pipe
10. ½" PVC Elbow 90 degr.
female
11. 1" - ½" Bush
12. 1" - ¾" Bush
13. ¾" -
½" Bush
14. ½" control gate
valves
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