Q4. What six items are required for pipe installation?
Q5. A trench bottom should be sloped in what direction?
Q6. What person sets and checks the elevation of pipe that is layed in trenches?
Q7. What are the four types of sanitary drainage piping used in underground sanitary plumbing?
Q8. What is the laying length of cast-iron soil pipe?
Q9. Vitrified clay pipe can be cut with a chisel. It can also be cut with what otherpiece of equipment?
Q10. PVC is what type of pipe? What does the acronym "PVC" mean?
Q11. What is the difference between a fillet-welded joint and a fusion-welded joint for plastic (PVC) pipe?
LEARNING OBJECTIVE: Recognize the methods of installing and testing sanitary drainage piping. 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 Equipment Operator.
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.
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 ofContinue Reading