13.
89
Pipe Laying.
pipe a flexible ball and socket joint would be attached, the section finally being made watertight by means of blank flanges at each end.
After all the joints had been carefully protected by double wrapping, special slinging rings would be bloted
on to the pipe in the selected slinging positions, to
prevent damage to the pipe covering while laying was being
carried out.
Two laying lighters would emantime have been
prepared, each having two hand winches fixed approaching amidships, each winch carrying two wire ropes, thereby
giving four slinging points.
When a composite pipe has been lowered into the
water at the assembly yard a lighter would come alongside
the sea wall and take it over. The lighter would then be
towed into position and anchored over the line of anchor
blocks, ready for lowering the pipe to its allotted position
on the harbour bottom.
About half an hour before slack tide or earlier
if found possible the divers would go down and place rollers
on the harbour bottom along the proposed line and the pipe
would be lowered on to them, one end being brought as close
as possible to the end flange joint of the previous pipe laid. This should be comparatively easy, as the pipe being
empty would be light, only weighing 6 lbs. per foot run or
including a ball and socket joint about 1,900 lbs. in all.
The blank flange would then be removed, the pipe filling with water, and the joint would be pulled up tightly
by means of long screw bolts which would afterwards be
replaced by ordinary short jointing bolts. The lighter would then take the weight of the pipe and lift slightly,
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