THE NEW GAS MAIN.

Star (Christchurch), Issue 3439, 19 April 1879, Page 3

THE NEW GAS MAIN.

{By the Special Reporter of the LytteUon Times.) Mr Clomenshaw, tho onorgotic manager for the Ohristchurch Gas, Coal, and Coke Com-

I pany, is now engaged in a highly important (: work This is the laying of a now main, fe direct from the gasworks, to tako the pluco of » the two smaller mains that hare hitherto been yL in use. The now main consists of specially iron pipes, 18 inches internal 0'/ diameter, eaoh pipe being 12 feet long, and i woghing throe quartors of a ton. Both in- ? side and out the pipes are ooatod with a patent composition for the prevention of rust, the efficacy of which has been demonstrated by an experience of many years. In the flange of these pipe 9 there is an important provision for securing a good joint, the inside of the flange having a wide groove, into which the lead used for forming the joint is forced, rendering it absolutely impossible that the union of two pipes can be broken without breaking the pipeß themselves. When two lengths of pipe have been lowered into tho trench and it is desired to make tho joint, a Bpeoiivlly contrived collar is Blipped over one pipe, close ' up to the flange of the next, a packing of tarred twine having been previously rammed in. Molten lead is then poured into the space between the flange and the portion of the inserted : pipe, and as tho lead cools, it is compressed | by means of the ordinary calking irons. About 801bs weight of lead is required for eaoh joint. Work was commenced on Tuesday morning, tho line to be followed being along the Gasworks road, and over to the nortli side of tho Belt ; thence along tho Bolt ns far as Mudraß street. From this point tho main will branch away by pipes of reduced size, one of the main linos extending along tho South Belt, and the other northward along' Madras street/. About SO men aro engaged on the work, and up to last evening tho trenoh had been oxcavated along tho Windmill road as far as tho Belt, and tho pipes laid and covered in for tho greater part of tho distance. Tho depth of tho trench is seven feet, and it is kept us narrow as possible, bo as to reduco tho amount of labour. At eaoh joint, however, tho trenoh has to be considerably widened to afford room for tho workmen, and at nil theao place the sides of the cuttin" are well shored up. In crossing the Belt, the dopth of tho main will not bo less than niuo feet, as there it has to pass under tho largo sower which was constructed somo time sinco. Notwithstanding tho narrowness of tho Gasworks road, the traffic has not onoo been blocked, tho excavated earth being carefully put up into a very high ridge. From the progress already made, Mr Clomensbaw estimates that ho will have tho whole of the 18---inch main laid by tho end of next week, and consumers will spoodily roalißo tho effect by the inoreascd pressure on their burners. At this they are not likely to grumble, whatever they may do whon the succeeding accounts aro presontecl, tlio power of using a brighter light invariably tending to an incroasod consumption. As has boon already stated, the new main is to tako tho place of two smaller ones. These aro boing cut up into portublo sections by special appliances, und will be relaid elsewhere for the purpose of extending the Bystom of mains. J t may bo of interest to mention that tho end of oven an 18-inch main can now be hormotically scaled against tho escape of gas, by a very simple procoss. A circular- shaped bag, formed of Btout indiarubber cloth, is placed in tho end of the main, and is then inilatod by means of a pair of hand-bellows shaped exactly like a concertina. The sides of the bag aro thus forced against th© inaide o£ the pipe, and with such pressure that no gas can Eossible escape. The spooial castings of tho irge main, such as the bonds and f pieces, aro fine specimens of work, not tho slightest projection or sharp angle being found in them. Everything is bo arranged that the gas may flow on uninterruptedly. One other point has yet to be referred to, the system of levelling the pipes. The level used is a very long one, about 16 feet, and tho men appear to an ordinary observer to be putting the line of pipes to a dead level. Were this tho case, they would in time become seriously impeded by the accumulation of water. Cinder one end of the long level, however, is a plate of iron, the thickness of which is prop >rtioned to the fall desired in the pip.'c, and the end in view is thus attained with absolute certainty, while the workmen have only to watch the spirit levol in the ordinary way. At tho lowest points in a line of pipes, suitable eiphons are placed for tho withdrawal of water. The extension of the main along tho south belt, from the Windmill road to the Lincoln road, and thence along the Lincoln road to the Sunnvside Asylum, is progressing rapidly, {he workmen having now reached a point opposite Mr Buddenuau'B mill.