What six items are required for pipe
A trench bottom should be sloped in what
What person sets and checks the elevation of
pipe that is layed in trenches?
What are the four types of sanitary drainage
piping used in underground sanitary plumbing?
What is the laying length of cast-iron soil pipe?
Vitrified clay pipe can be cut with a chisel. It can
also be cut with what otherpiece of equipment?
PVC is what type of pipe? What does the
acronym PVC mean?
What is the difference between a fillet-welded
joint and a fusion-welded joint for plastic (PVC)
LEARNING OBJECTIVE: Recognize the
methods of installing and testing sanitary
Small pipes can be assembled and joined in
sections on top of the ground and laid in the trench by
hand. Large, heavy pipes are usually laid in the trench
and then joined. These pipes may be lowered into the
trench by rope, cable, or chain. Larger pipe may
require the use of machinery operated by an
When assembling and joining pipes outside the
trench, make sure you are a safe distance from the edge
of the trench to prevent cave-ins. Also, do not leave
tools or materials near the edge of a trench where they
may be knocked off and injure someone working in the
trench or cause a worker to loose his or her footing and
fall into the trench.
Sewer pipes should be laid on a compacted bed of
sand, gravel, or material taken from the trench
excavation, if suitable, to provide a slightly yielding
and uniform bearing. This step assures safe support for
the pipe, the fill, and the surface loads. When pipes are
laid on sand, gravel, or similar material, the weight of
the pipe usually provides a suitable equalizing bed.
Pipelines should be embedded carefully, so they
do not settle at any point. Settling causes suspended
matter to collect in the lower portion of the pipe
restricting the flow and reducing the handling capacity
of the line.
TRENCHING AND GRADING
After you have laid the pipes, your next step is to
check the grade and align the pipeline. This is very
important in installing an underground sewer system.
Remember, sewage does not flow uphill, unless of
course you are using a pump, such as a lift station does.
The pipe should be laid, so the flow of the sanitary
waste in each length of pipe flows from the hub end to
the spigot end or we could say the hub end is upstream.
Each length of pipe should be placed starting at the
lowest elevation and working up the grade; therefore,
the spigot is inserted into the hub of the length laid
previously. Each length should be checked as to its
grade and alignment before the next length is placed.
When you are grading for the proper pitch per foot,
the method shown in figure 3-31 may be used as a
guide. This figure shows a ditch with batter boards
used in transferring line and grade to trench; also, a
stick for checking grade is shown in position.
An Engineering Aid (EA) is responsible for setting
the batter boards at the proper level for the job at hand.
Batter boards are placed across the trench at about 25.
to 50-foot intervals. Elevations are run by an EA, and a
mark is placed on the stakes at some even-foot distance
above the invert (the lowest point on the inside of the
pipe) of the sewer. A nail is then driven in the top of the
batter boards, and a cord is stretched from board to
board. The center line for the pipe is then transferred
from the cord to the bottom of the trench by means of a
plumb bob. Grade is transferred by means of a stick,
marked in even-foot marks, having a short piece
fastened at a right angle to its lower end. Grade is
checked by placing the short piece on the invert of each
length of sewer pipe and aligning the proper mark on
the grade rod to the cord.
After you complete the rough-in piping of a
project, test and inspect all the piping for leaks. The
purpose oftesting the pipeline is to make sure the joints
are tight enough to withstand working pressure. Since
a sewer line of this type flows by gravity drainage, the
test procedures are different than those described later
under the heading of Water Service.
Before the pipe is covered with dirt, it must be
tested for leakage. There are several methods of