Q 80
(3) Laying of Pipe Lines.
150. Excellent progress was made by the contractor (Messrs. Woo Hing), with the laying of the composite lengths, but frequent interruptions were caused by difficulties in the preparation of the harbour bed. The laying of the 222 composite lengths in the main lines was completed on May 18th in a total of seventy-eight working days. The laying of the land connexions was necessarily slow because it was essential to maintain the supply of water from the mainland through one of the two existing mains. While a restricted supply was maintained through the existing 18" diameter main, the 12" diameter main was dismantled under Queen's Pier and replaced by the new 21" diameter Western main. The Kowloon land connections at the railway were then altered at the end of August and the supply to Hong Kong maintained through the new main. Finally the 18" diameter main at Queen's Pier was replaced by the second new 21" diameter and full supply opened up on 30th October. On test the two pipe lines discharged 9.67 million gallons per day to the Hong Kong Gardens service reservoir with a leakage of 2,520 and 5,240 gallons per day in the East and West mains respectively or approximately .08 per cent of the total water delivered. The new mains are laid parallel to and about forty-two feet to the West of the old mains and their length from sea wall to sea wall is 5,909 feet.
151. The composite lengths, fifty feet long and 7.35 tons in weight, were slung in a specially constructed cradle suspended from a barge. The cradle consisted of two longitudinal mild steel joists 20″ × 7″ x 40'-0" long, braced on top with angle irons and channels the latter carrying two trolleys at 24'-7″ centres spaced symmetrically about the length of the joists. The pipes were supported in the cradle by mild steel straps suspended from the two trolleys, with three additional wire slings with tightening screws, when the pipe was slung in air. These extra slings were released by divers when the pipe was under water thus giving two point suspension. The cradle was lowered by steam winches from the barge and under instruction from divers on the harbour bottom the barge was moved into position so that the cradle could be lowered on to concrete bearer blocks placed on a rubble foundation at 16′-5″ intervals throughout the length of the line. By operating the gearing on the trolleys the divers could within limits move the pipe in three dimensions until the new pipe butted up to the one previously laid. Two pipes were then jointed together by the divers by means of Victaulic couplings specially made to give a deflection of two degrees, and the pipes secured in position in the saddles of the bearer blocks by billian wedges. The suspension clamps were then unhooked from the trolleys and the cradle raised to the surface and the clamps uncoupled from the pipe. The laying was generally carried out at slack water and when the tides were favourable the whole operation of laying and jointing a pipe was completed in a little over one hour.
152. In the central section of the line, where the pipe line is above the harbour bed, the joints are protected by grease encased by a cast iron cover, but where the pipe is laid in a dredged trench at both ends of the line, the grease protection was covered with a heavy canvas wrapping, the trenches being subsequently filled in. Where the cast iron covers were used the grease was moulded by hand to the approximate shape and after the cover had been fixed a special quality of grease was pumped in under pressure to ensure the filling of the cover.
153. Expansion joints were laid in the mains at intervals of approximately 600 feet and where the change in grade of the prepared harbour bed exceeded one degree a short double Victaulic piece was inserted to give extra flexibility.
154. A rubble mound seven feet high was constructed on the East side of the mains, in the central section of the harbour to protect them from dragging anchors, while over the end sections, the pipes were laid in a dredged trench with a minimum cover of six feet below harbour bed level.
155. The old 18" diameter main was lifted and reconditioned for use elsewhere. This is dealt with under Supply Mains for Kowloon Chai Service Reservoir. The old 12″ diameter main which did not justify the expense of recovery has been left on the harbour bed as additional protection for the new mains from dragging anchors.
Q 80
(3) Laying of Pipe Lines.
150. Excellent progress was made by the contractor (Messrs. Woo Hing), with the laying of the composite lengths, but frequent interruptions were caused by difficulties in the preparation of the harbour bed. The laying of the 222 composite lengths in the main lines was completed on May 18th in a total of seventy-eight working days. The laying of the land connexions was necessarily slow because it was essential to maintain the supply of water from the mainland through one of the two existing mains. While a restricted supply was maintained through the existing 18" diameter main, the 12" diameter main was dismantled under Queen's Pier and replaced by the new 21" diameter Western main. The Kowloon land connections at the railway were then altered at the end of August and the supply to Hong Kong maintained through the new main. Finally the 18" diameter main at Queen's Pier was replaced by the second new 21" diameter and full supply opened up on 30th October. On test the two pipes lines discharged 9.67 million gallons per day to the Hong Kong Gardens service reservoir with a leakage of 2,520 and 5,240 gallons per day in the East and West mains respectively or approximately .08 per cent of the total water delivered. The new mains are laid parallel to and about forty-two feet to the West of the old mains and their length from sea wall to sea wall is 5,909 feet.
151. The composite lengths, fifty feet long and 7.35 tons in weight, were slung in a specially constructed cradle suspended from a barge. The cradle consisted of two longitudinal mild steel joists 20′′ × 7′′ x 40'-0" long, braced on top with angle irons and channels the latter carrying two trolleys at 24'-7′′ centres spaced symmetrically about the length of the joists. The pipes were supported in the cradle by mild steel straps suspended from the two trolleys, with three additional wire slings with tightening screws, when the pipe was slung in air. These extra slings were released by divers when the pipe was under water thus giving two point suspension. The cradle was lowered by steam winches from the barge and under instruction from divers on the harbour bottom the barge was moved into position so that the cradle could be lowered on to concrete bearer blocks placed on a rubble foundation at 16′-5′′ intervals throughout the length of the line. By operating the gearing on the trolleys the divers could within limits move the pipe in three dimensions until the new pipe butted up to the one previously laid. two pipes were then jointed together by the divers by means of Victaulic couplings specially made to give a deflection of two degrees, and the pipes secured in position in the saddles of the bearer blocks by billian wedges. The suspension clamps were then unhooked from the trolleys and the cradle raised to the surface and the clamps uncoupled from the pipe. The laying was generally carried out at slack water and when the tides were favourable the whole operation of laying and jointing a pipe was completed in a little over one hour.
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152. In the central section of the line, where the pipe line is above the harbour bed, the joints are protected by grease encased by a cast iron cover, but where the pipe is laid in a dredged trench at both ends of the line, the grease protection was covered with a heavy canvas wrapping, the trenches being subse- quently filled in. Where the cast iron covers were used the grease was moulded by hand to the approximate shape and after the cover had been fixed a special quality of grease was pumped in under pressure to ensure the filling of the cover,
153. Expansion joints were laid in the mains at intervals of approximately 600 feet and where the change in grade of the prepared harbour bed exceeded one degree a short double Victaulic piece was inserted to give extra flexibility.
154. A rubble mound seven feet high was constructed on the East side of the mains, in the central section of the harbour to protect them from dragging anchors, while over the end sections, the pipes were laid in a dredged trench with a minimum cover of six feet below harbour bed level.
155. The old 18" diameter main was lifted and reconditioned for use elsewhere. This is dealt with under Supply Mains for Kowloon Chai Service Reservoir. The old 12′′ diameter main which did not justify the expense of recovery has been left on the harbour bed as additional protection for the new mains from dragging anchors.
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