I have no hesitation in telling that quality is the first casualty in execution of government jobs whether buildings, bridges, roads, irrigation canals and in supply items as well. First, the quality of inputs like sand, stone chips, bricks, cement, and road making ingredients is not properly checked. Second, quality suffers due to bad workmanship. Thirdly, quality suffers due to lack of proper supervision.
Now, let us be job specific. In Guwahati laying of 36-inch main water line is under progress to supply potable water to every household. Despite various commitments, water has not yet reached at the doorsteps of residents. At the same time it is pertinent to mention that we have not witness laying branch lines as yet. Once water supply network is commissioned, it becomes a lifeline for the citizens of Guwahati. As such frequent shutdowns for maintenance of lines are not advisable. It also does not need any maintenance for minimum 20/25 years; if quality of jobs is maintained. The hydro testing is done to ensure that no leak exists in welding joints. Underground (U/G) lines are hydro-tested segment wise progressively before it is laid and back filled. So far we have seen two accidents, while carrying out hydro testing. Fortunately there had been no casualty. One incident occurred probably 7/8 months back and the other happened in one month or so. Water lines are not high pressure lines. It is wrong to suggest that such failures are common during hydro testing. Only bad workmanship and non-adherence to set procedures could result in failures.
It is mandatory to engage only qualified welders for welding. Some procedures are to be followed for pipe welding and testing: joint preparation, fit-up and then welding. The welder will carry out root run and subsequent runs depending upon the thickness of the pipe. Then non-destructive tests (DP and radiography) are to be conducted on welding joints as defined in inspection and test plan (ITP), to see the soundness of the welding joint. For pre-coated pipes, hydro-testing of the line can be carried out after completion of welding joints. In case of un-coated pipes, coating and wrapping required to be done on the pipe, after hydro-testing is complete. Some precautions are required to be followed while doing hydro testing. Bind flanges are used to block the two ends of pipe to be tested must be thicker than the wall thickness of the pipe. The blind flanges are also reinforced by welding stiffener plates at outside surface of the plates. The pressure gauge used for testing needs to be calibrated first. Testing pressure is 1.5 times the design pressure. If the procedures are followed properly, there is no chance of any failure. In the first mishap, we have seen that at one end, the blind flange got removed partially. The welding joint failure was quite evident from that accident. That was a clear case of bad workmanship.