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The Sewerage of Sea Coast Towns by Henry C. Adams
page 91 of 154 (59%)
cold, are unsuitable for use below high-water mark on account
of the water which will most probably be found in the trench.
Pipes having plain turned and bored joints are liable to be
displaced if exposed to the action of the waves, but if such
joints are also flanged, as Fig. 24, or provided with lugs, as
Fig. 23, great rigidity is obtained when they are bolted up; in
addition to which the joints are easily made watertight. When a
flange is formed all round the joint, it is necessary, in order
that its thickness may be kept within reasonable limits, to
provide bolts at frequent intervals. A gusset piece to stiffen
the flange should be formed between each hole and the next, and
the bolt holes should be arranged so that when the pipes are
laid there will not be a hole at the bottom on the vertical
axis of the pipe, as when the pipes are laid in a trench below
water level it is not only difficult to insert the bolt, but
almost impracticable to tighten up the nut afterwards. The
pipes should be laid so that the two lowest bolt holes are
placed equidistant on each side of the centre line, as shown in
the end views of Figs. Nos. 23 and 24.

[Illustration: Fig. 2l.-Stoneware Pipe and Concrete Sea Outfall.]

With lug pipes, fewer bolts are used, and the lugs are made
specially strong to withstand the strain put upon them in
bolting up the pipes. These pipes are easier and quicker to
joint under water than are the flanged pipes, so that their use
is a distinct advantage when the hours of working are limited.
In some cases gun-metal bolts are used, as they resist the
action of sea water better than steel, but they add
considerably to the cost of the outfall sewer, and the
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