Connections to Water Mains

Connections to Water Mains

Connections to water mains are undertaken by an experience water contractor after certain amount of fees has been paid to the water board authority. The mains will have to be exposed and great care must be taken at all the times that the holes in the road are well graded to prevent accidents. A staffing box is clamped to the main which is under pressure and a hole is drilled in the main and a plugged connection made. The taping will generally be done at some convenient point along the tap of the main and will be arranged if possible to allow the new service pipe to run away at right angle to the mains. The arrangement is simple as it is often helpful in locating the route of a pipe which later has to be dug up for repairs (Townsend, 1989).

Taping of the Water Mains

The taping of the Water mains for connection to a building or a project is done in the following two (2) methods:

i. Under-pressure:

The taping under this method is done using a special machine which consist of a water fright base that is attached to the main pipe by chaining, then the hole drilled or punched and a ferrule is brought directly over the hole and screwed into it for connection to the communication pipe as the name implies, the hole is made and water gush out with extensive pressure and in

This case the main’s water is not interrupted (Townsend, 1989).

ii. Non-pressure:

In this connection, “tee-junction” joints are at a strategic location along the main’s line and connections are made through the “tees”. However, a gate or globe valve is screwed down for shutting off supply for the connection (Townsend, 1989).

Components of Distribution of Water Supply

The main components of distribution of water supply are various pipes, assorted valves, hydro-sets, meter services, distribution pipes and taps.
a. Pipes: these are constructed using any one of the following materials;
i. Cast iron
ii. Steel or galvanized mild steel
iii. Cement
iv. Concrete
v. Plastic

Pipes are classified according to the distribution of water supply system.

b. Mains: These are used for conveyance of water over a long or short distance and for distribution of water supply through the nooks and crannies of the cities. Mains principally are referred to as the larger sized in diameter pipe line which transmit water from the water board.

c. Service pipes: These are used as individual supply lines to houses or project sites. They are connected to the mains and redirected to the buildings.

d. Valves: These are used to cut off or control the supply of water through pipe work. Valves are provided on a distribution system principally to isolate areas for emergency maintenance. In a normal distribution, supply valves are larger than 300mm and should be operated at least once a year. There are different types of valves which include the following:

i. Air valves: These are used at summits in the pipe line for the removal of air and the pressure of which will reduce the effective area of the pipe. Cork floats are usually provided to regulate the control of the valve.

ii. Check valves: These allow for one direction control. The valve is fitted with a flap which swing or pivot to open and allow water to flow in one direction, the flow stops, and the flat drops to its seat or position and prevent back flowing.

iii. Gate valves: These are used in low pressure system for shutting off or controlling the flow. The gate valves are provided in both intersecting pipe lines, and manholes are constructed at each valve location to provide easy access in order to carry out repairs when necessary.

iv. Globe valves: These look rigid just like gate valves and are used on high pressure pipe lines to isolate components or control flow.

Distribution Joints in Water Mains

Fittings are identified by the sizes of pipe that are connected to their openings. There are various methods of joining pipes for water distribution systems. Each method used is designed to withstand internal (hydrostatic) pressure in the pipe and normal soil loads if joints and connections are below ground. Some of these methods produce the types of joints and connections described below (Parts Query).

Types of Joints for Water Mains

Pipes jointing is done in order to increase the length and to change direction of flow. Joints are classified as follows:

a. Rigid joints: These include turned and bored spigot socket joints and flange joints. The turned and socket joint may either be whole turned and bored or half turned and bored. The spigot end is lathed turned to a tapered metal-to-metal fit in lathe bored sockets.

These joints have the advantage of being self-centering but need extra care in assembly. The pipes may be dead in line otherwise the tapered spigot will not be pushed squarely into the bored socket because of this and in fact these joints do not allow unwanted movement of the pipe at all, not even in small deflection to pass an easy carves in the road. However, they are seldom in use nowadays.

In the case of the half turned and bored joint, the annealing space in the top half of the socket is filled and caulked with hot red lead, or the situation is so damp with lead wool.

b. Semi rigid joint: These are joints of the caulked spigot and socket which allowed some form of flexibility in the pipe line are often used for joints in the mains. Beads are more often left off the spigot now because test and experience have shown that unbeaded spigots can adjust themselves better to pipe movement without leaking.

c. Flange joints: These are constructed by bolting together flanges which are cast as part of the pipe. Thin rubber rings are placed before the machine face off the flanges and are compressed in the bolting position. Flange joints must be made with utmost care. The face of the flange must be kept clean and accurately in line with each other.

However, flange joint does not increase length but in order to allow for expansion and contraction considerably, some form of relieving joint must have to be incorporated in the pipe line at some suitable point along their length.

d. Disconnecting joint: When connecting pipe work up to appliance and components that may need to be remove or disconnected for maintenance such as boilers, pumps, and tanks, special fittings need to be used that can be loose easily without affecting the surrounding pipe work.