COMMON COMPETENCIES
Learning Objectives
After completing this section, you are expected to:
I. Prepare plumbing construction material and tools
II. Observe procedures, specifications and manual of instruction
III. Interpret technical drawings and plans
IV. Evaluate the mensuration and calculations in plumbing
V. Define how to maintain tools and equipment
Introduction
A competency is defined as a combination of knowledge, skills and abilities which when acquired, allows a person to
perform a task or job at a specifically defied level of proficiency. Plumbing is a system of pipes, drains, fittings,
valves and fixtures installed for the distribution of potable water for drinking, heating and washing and waterborne
waste removal.
I. Prepare plumbing construction materials
A basic plumbing materials consists of the following:
1. Fittings.
These are the metal links that connect pieces of pipes with or without a change in direction. Some are made
to connect different sizes of pipes and others, to divert, divide or return the flow of water in the pipe. Pipe
fittings connect to pipes in one of two ways: by thread or by slip fit. Metal pipes are threaded while plastic
pipe can be threaded or slip fit pipe use sleeves that slip into one another. They are organized by male and
female connectors as follows:
Male threaded: threads are exterior, made to screw into the inside of a larger diameter pipe end with
internal threading
Female threaded: threads are interior, made to receive male threaded fittings.
Male slip fit: No thread, made to slip into slightly larger female sleeve.
Female slip fit: No thread, made to receive a narrower male slip fit.
Fittings are usually made of the same materials as the pipe with which they are used. End connections are
made for either screwing, or flanging, or welding.
Elbows “commonly called ells” are fittings which change the direction of a pipe run. They come in a
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variety of angles; the most popular are 90, 60, 45, and 22 degree turns. A cross fitting open in four
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directions each at 90 degrees to the one next to it. The Y-bend differs from T’s that they branch off at 45 instead of
90-degree angle.
Reducing fittings permit joining pipes of different sizes. If a reducing fitting is not available, you can use a bushing
with a standard fitting to reduce one of the openings to the desired size. Caps close the male ends of fittings, and
plugs close the female ends.
Couplings are most often used to join two sections of pipes of the same sizes.
Nipples are short pipe used to connect various fittings to the fixture
Unions are used to facilitate joining and dismantling.
2. Flexrock packing
In some cases, where the threading on a trap is imperfect, or you need to seal a leak at the junction of pipe
or trap, either wicking or flexrock packing can be used. This is a metallic, self-forming, self-lubricating
packing. You can also use it to stop leaks in the spout of a combination or deck faucet, in slip joint
connection, and radiator valves. Flexrock packing is wound around the tail piece below the coupling nut or
loose head coupling. When the nut tightened, the pressure molds the packing into a lead-like washer. It can
be used for piping conveying either cold or water, and is resistant to air, brine, gas, ammonia, and other mild
chemicals.
3. Hangers
Hangers are fixtures used to support pipe running along walls or ceiling. These are commercially available in
several sizes and shape or you can make them from iron piping or lumber frames. They are necessary to
keep long runs of piping from sagging and weakening at the joints.
4. Hardware
Various hardware supplies (screws, nails, gaskets, etc) find use in plumbing work. they are usually made of
steel, iron, or rubber.
5. Insulating materials
Hair and wool felt, cork, asbestos, and various mineral insulators such as mica, and mineral wool are used to
insulate pipe systems where it is necessary to prevent loss of heat or protect occupants of the house from
burns.
6. Lead
Lead finds several uses in plumbing. Lead pipes are common in some installations; sheet lead is used as a
water-proofer; molten lead is often used to seal joints in cast iron pipe.
7. Oakum
Oakum is a loose, stringy fiber used to pack seams and joints when caulking. It is forced into the hub of
jointed pipes with caulking irons to form a seal prior to leading.
8. Pipe
The all-inclusive term pipe covers a variety of tubular materials which differ in size and composition. Each
kind has its purpose or is suggested as being best for a specific use. In plumbing work the most commonly
used are cast iron, galvanized iron, and galvanized steel. Cast iron finds use in water pipes, soil pipe, vent
pipes, sewer, and traps. All three are used for fittings in water, drainage, and vent systems. Although iron
and steel pipes are subject to corrosion, their strength, versatility and low cost make them suitable for
structural purposes. Lead pipe is used more in drainage systems than in water systems because it is affected
by chemical agents in the water. Since soluble lead products are sometimes poisonous, the use of lead pipe
should be confined to drainage piping and making joints in cast iron piping.
Copper tubing is better conveyor of hot and cold water supplies because it does not corrode except
when attacked by dissolved gases in the water; soluble copper is not harmful. Brass and bronze are
used extensively because they are non-corrodible except with certain types of soft water. As a
result, they excellent for water piping where corrosion would affect functioning.
Vitrified clay pipe is used chiefly in sewer system because it can easily be made in larger size and
withstands almost every kind of corrosion.
Factors governing selection of pipe. Although it always contains oxygen and carbonic acid, perfectly
dry air will not rust iron. Moisture must be present to absorb the carbon dioxide, Sulphur dioxide,
and other acidic agents from the air. These gases react with the water to form carbonic acid,
sulphuric acid, or other acids. Acid water tends to attack iron or steel while alkalies tend to check
their rusting.
Soft waters are more corrosive that hard waters. Soft water such as rain water, corrodes, then
washes away the corrosion, and the action continues. Waters known as temporarily hard, those
containing carbonates in solution, protect the metal by depositing an insoluble coating while
permanently hard waters, which includes sulphates, do not form a permanent coating.
Water must contain dissolve oxygen and an acid to corrode iron. While aeration reduces carbonic
acid in water, it adds dissolved oxygen which will cause rusting if any acid is present. Salty waters are
very corrosive, chiefly on account of the chlorine.
9. Sandpaper, steel wool, and sand or emery cloths
These abrasives are most frequently used to remove rust patches, brightens copper fixtures and clean
surfaces prior to soldering.
10. Sheeting (zinc, tin, and lead)
Sheets of zinc, tin or lead are used to make flashings which prevent water leaks and to line pipes as a
protection against corrosion.
11. Valves and faucets
Valves are device use to control the flow through pipes of either gas or water. They may be operated
manually or automatically, depending on the needs of the system they help control. The faucet which
releases and regulate the flow of water, is a common manual valve.
12. Wicking
A packing material used when making pipe junctures as a preventive against leakage, lamp wicking is the
most common type of water and waste lines, when there is no heat present. In the event of prolonged heat,
asbestos wicking should be employed. Wicking is often used by plumbers to cover up bad cut thread on the
pipe. This is extremely bad practice and should be avoided as the cure is only temporary and will eventually
result in weakness.
Types of Plumbing Pipes
1. Metal Pipes
a. Copper: this type of pipe is very reliable but expensive. Copper pipes are highly resistant to corrosion,
tolerant to heat, and not prone to leaks, since the connection are soldered and fitting stay tight. Copper
pipes comes in three sizes: M (very thin walls), L (medium thickness), K (thickest walls). Types M and L
are usually used for interior hot and cold supply lines, while type K serves for underground service lines.
Copper pipe biggest drawback is price.
b. Galvanized Steel: these gray metals are extensively used in home plumbing in the early 60s particularly
outdoors and are slightly resistant to corrosion and rust. They are usually replaced PEX and HDPE pipe in
home plumbing
c. Stainless Steel: stainless steel pipes are strong and highly resistant to corrosion but even more
expensive than copper pipes. They are most often used in marine environments where saltwater would
corrode other metal pipes.
d. Cast iron: it is very durable but difficult to work with because of its weight. If you need to replace broken
cast iron pipe, PVS is a good choice because it joins well with cast iron.
2. Plastic Pipes
a. Grey plastic Polybutylene (PB): Gray or beige, usually solid in coils. This was extensively used from the
late 1970s to the mid-1990s as an expensive replacement for copper. Over the years, PB has proven to
be prone to leaks that deprive its use to present time.
b. Creamy Plastic Chlorinated Polyvinyl Chloride (CPVC): Yellowish or beige in color. This is a PVC pipe that
has been given extra chlorination. More reliable than PB and less expensive and easier to install than
copper, it can be used for cold and hot water supply. It is more flexible than PVC but should not be
buried, as it will split if it freezes.
c. Polyvinyl Chloride (PVC): White or gray pipe used most often to carry high pressured water. although it
cannot be used with hot water, which can cause the pipe to warp, it is often used for the main supply
line into a home. PVC comes in sizes ranging from ½” to 4” in diameter, and it is work with inexpensive
and very easy to work with.
d. Cross Linked Polyethylene (PEX): This type of pipe is used extensively for interior plumbing in new
homes. PEX resist heat much better than most plastic pipe so it is often used for water-based heating
systems.
e. High Density Polyethylene (HDPE): This plumbing pipe is high resistant to corrosion, flexible, and very
long lasting, and can be used to carry everything from drinking to compressed gas to hazardous waste.
HDPE comes in long length, and joints are formed through heat fusion, eliminating leaks. It has usually
low resistance, or drag, making it a good choice for virtually all plumbing applications.
