30 General Notes on Plumbing-Sanitary and Sewerage Work
General Guidelines for Plumbing Sanitary pipeline works:-Here I am going to discuss important Guidelines for plumbing sanitary & sewerage pipeline works.
1). Where a pipeline crosses a road or a drain, it shall be through C. I or R.C.C. Pipe.
2). When G.I pipe is embedded in walls or floor, It should be painted with anticorrosive bitumastic paint. Under the ground floor, the pipe shall be laid in a layer of sand Filling. The pipe shall not come in contact with lime mortar or lime concrete as the pipe is affected by lime.
3). The G.I pipe shall not ordinarily be buried in walls or solids floors. They shall remain clear of the wall by 1.5cm.
4). Where pipes are crossing a wall or floor, an M.S . tube or sleeve be provided for the reception of the pipe and to allow freedom for expansion and contraction.
5). Minimum Clearance of 30 cms. Below the water tank at the roof should be given to permit easy cleaning of the terrace below the tank.
6). It is desirable to provide an air vent pipe on the outlet pipe from the tank to avoid possible occurrences of the airlock.
7). In-tank, It is a must to provide an overflow pipe or/and an air vent pipe. If there is no way for air to escape, then if water is filling in the tank, air well compressed and may lead to bursting of the tank. Similarly, Without an air pipe there no way to enter to tank, When the water level goes down. So there may be a partial or full vacuum in the tank when water in the tank goes down and the tank may compress by outside atmospheric pressure. Because of vacuum, the effective pressure at exit points of water supply will also be less.
8). The desirable temperature of potable water = 10 Degree C.
9). After putting “Safeda” in pipe threads during the joining of pipes, water can be opened immediately. There is no need to wait for such type of joining.
10). If branch waste pipe length is more than 150 cm before it is connected to a mainline or where more than one fixture is connected to an unvented branch line, separate vent pipes for their trap seals should be provided. Appliances should be grouped as closely as possible around the main stuck or pipe to reduce the length of branch lines.
11). The greater the depth of the seal, the more effectively it will prevent foul air to come to the house. Waste pipe (bath, sink, washbasin, or kitchen ) should be connected to the mainline sewer, only through a gully trap so as to maintain them separately and to keep waste matter separate from the soil meter.
12). For direct connection of W.C to O.H.T (instead of flushing tank in between )
i). More diameter of the pipe is required right from O.H.T to W.C (2”)
ii). Flush out valve or push-button arrangement required in the pipe to discharge the water to W.C normal stop cock can be put in place of flush valve but the harm is if somebody leaves it open in a certain position, water will constantly go waste.
13). For urinals also, instead of cisterna flush out valve with spring lever arrangement can provide direction in the line when the hand pressure below, water in the pipeline will come. As soon as hand pressure is released lever will automatically go up because of spring action and water will stop flowing the pipeline.
14). Residual head at water top should not be less than 0.35kg/cm or 10 feet.
15). Gate valve, if used for frequently varying the discharge, will spoil soon, It should be either fully closed or fully opened. Where varying discharges are required globe valve is preferred (more costly than a gate valve ).
16). Steel/G.I tanks can be internally painted with bitumens paint to avoid corrosion. This paint doesn’t impart any taste or odor to the water.
17). The pipes used in the distribution system shall be of the following types & grades –
a). G.I. pipes shall be of class B and C.
b). C.I. pipes shall be class L.A.
c). A.C. pipes shall be of class III i.e having a test pressure of 15kg/cm.
d). P.V.C pipes shall be for a working pressure of 6kg/cm.
18). Pipes shall be laid with a minimum cushion of 2 ft. Under the beams and 4 ft . under the roads.
19). Special care should be taken to ensure an adequate horizontal and vertical separation between water & sewer pipes. As far as practicable, the lateral separation should be 3 meters and vertical ½ meter clear. A water main should be neither pass through nor come in contact with any part of a manhole.
20). All water distribution mains shall be tested for at least twice the maximum working pressure of pipes and joints shall be absolutely watertight under the test.
21). A minimum spacing of 500 meters shall be kept between adjacent tube wells including existing tube-well in the neighborhood.
22). The tube well shall be located in a plot of at least 30 meters X 30 meters in size.
23). The fire hydrates should be provided preferably on 150 mm diameter and above the size of water mains proposed in the water supply scheme. When the entire system is 100 mm dia then fire hydrants may be marked on 100 mm diameter water mains.
24). The fire hydrants should be provided preferably on the water mains proposed along main roads as it will facilitate the movement of fire tenders.
25). Fire hydrants should be located at a distance of 150 meters from center to center in the distribution system in such a way that a fire hydrant is available within a distance of 75 meters anywhere in the system.
26). Extra excavation should be done under the joints of sewer pipes for filling the joints properly so that there is no infiltration.
27). In Case I.L of the sewer from the colony is higher by more than 2 than the I.L of the municipal sewer at connecting manholes, drop connection shall be provided as per municipal deigns.
28). Crossing of nullah etc. shall be done by C.I pipes.
29). The vent pipe shall be provided at every head of the sewer, at every drop every junction manholes, and at 800 ft. distance on straight length. The height of the same shall be as per drainage by law.
30). For pumped supply, if the diameter of the pipe is increased, velocity will be decreased although discharge will be slightly increased because of less friction with a larger diameter of the pipe. For gravity supply by Overhead water tank (O.H.T). If the diameter of the pipe is increased (Other conditions remaining same )velocity will increase in discharge will be much more compared to pumped supply because of higher velocity and less friction of larger dia . of pipe.
I earnestly hope that these guidelines have been both meaningful and useful to you.
Thanks For the Great Attention!
Good Bye & Take Care