Main breaks ( Main pipeline Work ) 

 Pipeline bursts/ main breaks can occur at any time and the maintenance wing shall have a plan for attending to such events. This plan must be written down, disseminated to all concerned and the agency must always be in readiness to implement the plan immediately after the pipe break is reported. After a pipe break is located, determine which valve is to be closed to isolate the section where the break has occurred. Some important consumers may be on the transmission system and having an industrial process dependent on water supply which cannot be shut down as fast as the water supply lines are cut off and should be notified about the break. These consumers have to be informed about the probable interruption in water supply and also the estimated time of resumption of water supply. After the closure of the valve the dewatering/ mud pumps are used to drain the pipe break points. The sides of trenches have to be properly protected before the workers enter the pit. The damaged pipe is removed, and the accumulated silt is removed from inside the pipe and the damaged pipe is replaced and the line is disinfected before bringing into use. A report shall be prepared following every pipe break about the cause of such break, the resources required for rectification and the time and cost required for repairing etc. so that the agency can follow up with measures for avoiding such breaks and also modify their plan to address such breaks in future

Deterioration of Pipes

 Pipes deteriorate on the inside because of water corrosion and erosion and on the outside because of corrosion from aggressive soil and water/moisture. Depending upon the material of the pipes these are subject to some deterioration, loss of water carrying capacity, leaks, corrosion and pitting, tuberculation, deposition of sediment and slime growth. Preventive maintenance of transmission system assures the twin objectives of preserving the bacteriological quality of water carried in the transmission mains and providing conditions for adequate flow through the pipelines. Incidentally this will prolong the effective life of the pipeline and restore its carrying capacity. Some of the main functions in the management of preventive aspects in the maintenance of pipelines are assessment, detection and prevention of wastage of water from pipelines through leaks, maintaining the carrying capacity of pipelines and cleaning of pipelines.

The preventive maintenance procedures related to transmission mains are listed below:

Regularly inspect at least once in a month transmission main alignments for  illegal or unauthorized tapping

1. Construction activities if any near the pipeline,
2. Slime growth in the pipes,
3. Leaks in joints and pipes,
4. Damaged structures of valve chambers, and
5. Inside of valve chamber with flash light for any accumulation of water resulted from valve leakage.
6. Flush the pipeline once in three months to remove deposits of silt and organic materials.
7. Maintain the alignment of the transmission mains clean by regularly removing the vegetative growths above the surface.

       Common defects in valves requiring repair include:

1. Broken stem,
2. Replacement of packing,
3. Internal incrustation
4. Accumulation of silt at the seat of the shutter

• Preventive maintenance of valves includes

1. Verifying location of valve box
2. Recording the count of the number of turns required for closing the valve fully
3. Checking the water tightness of valve closure with leak detector
4. Incrustation of internal moving parts can prevent full closure; Periodic opening and closing loosens the interfering scales.

• Frequency of inspection of valves

1. Valves in trunk, feeder, and pumping mains at least once a year,
2. Valves in the distribution network once in every one to three years