WATER FOR WELLINGTON
NEW MAIN NEARLY READY – TESTING AT HIGH PRESSURE
[BY TELEGRAPH.—OWN CORRESPONDENT.]
WELLINGTON, Monday.
With the exception of three short lengths, the new steel pipeline from the municipal reservoir at Wainuiomata is now laid and jointed. At the present rate of progress, the full length of over 20 miles from the Orongorongo intake chamber to the Karori storage reservoir should be completed within a month or six weeks.
However, the new water supply cannot be given to the city until the line is tested over the full distance, and this work is bound to occupy a considerable time. Wellington cannot expect the new supply for several weeks after the completion of the main. Experience in the Wainui Valley has shown that the testing of the main is a long and tedious job.
The new main will have to stand up to extremely high pressure—up to 346 lb. to the square inch. The Mangahao pipeline, it is stated, carries a heavier pressure, but in that case, riveting is the system of jointing employed. There has been a good deal of discussion regarding the steel and rubber joint employed in the Orongorongo-Karori main.
The pipes to be connected are butted together with a neatly fitting band ring covering the two ends. Rubber rings with a cross-section diameter of about three-quarters of an inch lie against either side of the band, and heavy cast iron collars are clamped by means of many bolts round the circumference of the pipe, hard against the rubber rings.
The line is being tested in position under very much more than normal pressures by means of the extra poundage given by a small-diameter pipeline, which has its intake at a point considerably higher than that of the main itself.
Under what may be styled laboratory tests, the joints have stood up to tremendous pressure—more than five times as great as the working strains—and one particular joint was still holding when the gauge blew up at a pressure of about 2000 lb.
Tags: Newspaper Orongorongo Pipeline Pipeline Waterworks
